IMATRON INC
8-K, 1996-07-01
ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS
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                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549




                                    FORM 8-K


                             CURRENT REPORT PURSUANT
                          TO SECTION 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934



         Date of report (Date of earliest event reported)      June 24, 1996
                                                         -----------------------

                                  IMATRON INC.
- --------------------------------------------------------------------------------
             (Exact Name of Registrant as Specified in Its Charter)

                                   New Jersey
- --------------------------------------------------------------------------------
                 (State or Other Jurisdiction of Incorporation)


        0-12405                                          94-2880078
- ----------------------------                ------------------------------------
(Commission File Number)                    (I.R.S. Employer Identification No.)

389 Oyster Point Boulevard, South San Francisco, CA                    94080
- --------------------------------------------------------------------------------
    (Address of Principal Executive Offices)                         (Zip Code)

                                 (415) 583-9964
- --------------------------------------------------------------------------------
              (Registrant's Telephone Number, Including Area Code)


- --------------------------------------------------------------------------------
          (Former Name or Former Address, if Changed Since Last Report)




<PAGE>

5.  OTHER EVENTS.

         Effective  June 24, 1996  Registrant  and its wholly  owned  subsidiary
HeartScan Imaging, Inc.  ("HeartScan")  entered into an agreement  ("Agreement")
with  certain  institutional  and  other  accredited  purchasers  ("Purchasers")
pursuant to which Registrant agreed to sell 100,000 shares of HeartScan Series A
Preferred  Shares  ("Shares") to the Purchasers for an aggregate of $16,000,000.
The Shares  represent all the Series A Preferred  Shares issued by HeartScan and
outstanding  and  all of the  HeartScan  Series  A  Preferred  shares  owned  by
Registrant.  The Shares are convertible,  as described  below,  into a 40% fully
diluted interest in HeartScan.

         Further,   the  Agreement   provides  certain   additional   rights  to
Purchasers.  The Shares may be exchanged for  Registrant's  common stock at each
Purchaser's option and without payment of additional consideration for a defined
period and at a defined  price,  and  thereafter  for an additional  period at a
different  price.  The first  exhange  period  begins on closing and ends on the
earlier  of two years or a  HeartScan  qualified  public  offering  as  defined.
Purchasers  may  receive  that  number  of  Registrant's  common  shares  as  is
determined by dividing $160 by $5.00.  The second  exchange period is a five-day
period  following  the second  anniversary  of the closing and a similar  period
following each quarter  thereafter until the fourth  anniversary of the closing.
Purchasers  may  receive  that  number  of  Registrant's  common  shares  as  is
determined  by dividing  $160 by 73% of the then trading  price of  Registrant's
common  stock,  but not less than $1.50.  Alternatively,  the  Shares,  by their
terms,  are also  convertible  into HeartScan common shares at a ratio initially
established at 1:10.

         Purchasers of Shares are also granted the right to purchase,  pro rata,
any new  securities  issued by  HeartScan  at the price  proposed  to be issued.
Purchasers are entitled to receive certain  financial and corporate  information
so long as they hold the Shares. Purchasers are entitled to elect two designated
representatives  to HeartScan's  board of directors so long as the purchasers in
the aggregate retain 20% of HeartScan's common stock (or shares convertible into
such common shares), or to elect one representative so long as the purchasers in
the aggregate  retain 10% of HeartScan's  common stock.  The right to designated
representatives  on the  board  of  directors  terminates  on the  earlier  of a
qualified  HeartScan  public offering as defined,  ownership of less than 10% in
the aggregate of HeartScan's common stock, or ten years from the closing.

         HeartScan  has agreed  that it will not engage in certain  activity  or
conduct, without written approval of two-thirds of the purchasers.  That conduct
includes entering into any material transaction with an affiliate; entering into
any additional business;  merging,  liquidating or selling substantially all its
assets;  issuing or selling any other stock except a qualified  public offering,
shares  already  reserved  for  purchase  pursuant to employee  plans,  or stock
issuable pursuant to this Agreement; declaring or paying dividends, or redeeming
stock other than  related to  terminating  employees;  or investing in any other
business.

ITEM 7.  EXHIBIT.

         10.1.  Stock  Purchase  Agreement  dated  as of  June  24,  1996  among
Registrant,  HeartScan  Imaging,  Inc.  and  Purchasers  Listed  on  Exhibit  A,
including Exhibits A, B, C, D and E.


<PAGE>



                                   SIGNATURES


         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  registrant  has duly  caused  this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                                   IMATRON INC.
                                        ----------------------------------------

Date: June 28, 1996                     By       /s/ Gary H. Brooks
                                        ----------------------------------------
                                                     Gary H. Brooks
                                        Its: Vice President, Finance and
                                             Administration, Chief Financial
                                             Officer and Secretary








                                  EXHIBIT 10.1

                            Stock Purchase Agreement
                           and Exhibits A, B, C, D & E


<PAGE>











                            STOCK PURCHASE AGREEMENT

                            dated as of June 24, 1996

                                      among

                      IMATRON INC., HEARTSCAN IMAGING, INC.

                                       and

                       THE PURCHASERS LISTED ON EXHIBIT A


<PAGE>

<TABLE>


                                                  TABLE OF CONTENTS

                                                                                                               Page
<S>                                                                                                              <C>

         ARTICLE 1         PURCHASE AND SALE OF SHARES..........................................................  1

                  1.1      Ownership of Shares..................................................................  1
                  1.2      Sale and Purchase of the Shares......................................................  1

         ARTICLE 2         CLOSING DATE; DELIVERY...............................................................  1
                  2.1      Closing Date.........................................................................  1
                  2.2      Delivery.............................................................................  1

        ARTICLE 3          REPRESENTATIONS AND WARRANTIES OF IMATRON............................................  1
                  3.1      Ownership and Title..................................................................  2
                  3.2      Organization and Standing............................................................  2
                  3.3      Corporate Power......................................................................  2
                  3.4      Subsidiaries.........................................................................  2
                  3.5      Capitalization.......................................................................  2
                  3.6      Authorization........................................................................  3
                  3.7      Financial Statements.................................................................  3
                  3.8      Absence of Undisclosed Liabilities...................................................  4
                  3.9      Changes..............................................................................  4
                  3.10     Title to Assets; Liens, etc..........................................................  5
                  3.11     Compliance with other Instruments, None Burdensome, etc..............................  5
                  3.12     Intellectual Property................................................................  6
                  3.13     Litigation, etc......................................................................  6
                  3.14     Employees............................................................................  6
                  3.15     Registration Rights..................................................................  7
                  3.16     Governmental Consent, etc............................................................  7
                  3.17     Offering.............................................................................  7
                  3.18     Material Contracts...................................................................  7
                  3.19     Licenses; Compliance with Laws.......................................................  7
                  3.20     Disclosure...........................................................................  8
                  3.21     Environmental and Safety Laws........................................................  8
                  3.22     Imatron Corporate Documents..........................................................  8
                  3.23     HeartScan Corporate Documents........................................................  8
                  3.24     Insurance............................................................................  8
                  3.25     Labor Agreements and Actions.........................................................  8
                  3.26     Brokers or Finders...................................................................  9

         ARTICLE 4         REPRESENTATIONS AND WARRANTIES OF THE PURCHASERS...................................... 9
                  4.1      Risk.................................................................................. 9
                  4.2      Experience............................................................................ 9
                  4.3      Principal Place of Business........................................................... 9

                                                         -i-

<PAGE>



                  4.4      Investment........................................................................... 10
                  4.5      Rule 144............................................................................. 10
                  4.6      No Public Market..................................................................... 10
                  4.7      Access to Data....................................................................... 10
                  4.8      Authorization........................................................................ 10
                  4.9      Brokers or Finders................................................................... 10
                  4.10     Investor Counsel; Investment Advisor................................................. 10

         ARTICLE 5         EXCHANGE RIGHTS...................................................................... 11
                  5.1      Certain Definitions.................................................................. 11
                  5.2      First Exchange Period Rights......................................................... 11
                  5.3      Second Exchange Period Rights........................................................ 13
                  5.4      No Impairment........................................................................ 14
                  5.5      Mechanics of Exchange................................................................ 14
                  5.6      Reservation of Imatron Common Stock.................................................. 15
                  5.7      Participation Rights Offering........................................................ 15
                  5.8      Notices of Record Date............................................................... 15

         ARTICLE 6         AFFIRMATIVE COVENANTS................................................................ 16
                  6.1      Use of Proceeds...................................................................... 16
                  6.2      Right of Participation............................................................... 16
                  6.3      Financial Information................................................................ 17
                  6.4      Purchasers' Right to Elect Directors................................................. 18
                  6.5      Termination.......................................................................... 19

         ARTICLE 7         NEGATIVE COVENANTS................................................................... 19
                  7.1      Dealing with Affiliates.............................................................. 19
                  7.2      Conduct of Business.................................................................. 19
                  7.3      Sale of Securities................................................................... 19
                  7.4      Liquidation; Merger, etc............................................................. 19
                  7.5      Dividends; Distributions; etc........................................................ 19
                  7.6      Investments.......................................................................... 20

         ARTICLE 8         TRANSFERABILITY OF SECURITIES........................................................ 20
                  8.1      Transferability...................................................................... 20
                  8.2      Restrictive Legend................................................................... 20
                  8.3      Notice of Proposed Transfers......................................................... 20

         ARTICLE 9         REGISTRATION RIGHTS RELATING TO IMATRON SECURITIES................................... 21
                  9.1      Certain Definitions.................................................................. 21
                  9.2      Registration of First Exchange Period Shares......................................... 22
                  9.3      Registration of Second Exchange Period Shares........................................ 22
                  9.4      Expenses of Registration............................................................. 23
                  9.5      Registration Procedures.............................................................. 23

                                                   -ii-

<PAGE>



                  9.6      Indemnification...................................................................... 25
                  9.7      Information by Holder................................................................ 27
                  9.8      Rule 144 Reporting................................................................... 27
                  9.9      Transfer of Registration Rights...................................................... 28
                  9.10     Additional Shares.................................................................... 28

         ARTICLE 10        REGISTRATION RIGHTS RELATING TO HEARTSCAN SECURITIES................................. 28
                  10.1     Certain Definitions.................................................................. 30
                  10.2     Registration......................................................................... 30
                  10.3     Registration on Form S-3............................................................. 30
                  10.4     Limitations on Subsequent Registration Rights........................................ 31
                  10.5     Expenses of Registration............................................................. 31
                  10.6      Registration Procedures............................................................. 32
                  10.7     Indemnification...................................................................... 34
                  10.8     Information by Holder................................................................ 36
                  10.9     Rule 144 Reporting................................................................... 36
                  10.10    Transfer of Registration Rights...................................................... 37
                  10.11    Standoff Agreement................................................................... 37

         ARTICLE 11        CONDITIONS TO CLOSING OF THE PURCHASERS.............................................. 37
                  11.1     Representations and Warranties Correct............................................... 37
                  11.2     Covenants............................................................................ 37
                  11.3     Qualifications....................................................................... 37
                  11.4     Legal Matters........................................................................ 37
                  11.5     Proceedings and Documents............................................................ 38
                  11.6     Opinion of Imatron's and HeartScan's Counsel......................................... 38
                  11.8     Good Standing........................................................................ 38
                  11.9     Equipment Supply Agreement........................................................... 38

         ARTICLE 12        CONDITIONS TO CLOSING OF IMATRON..................................................... 38
                  12.1     Representations...................................................................... 38
                  12.2     Further Representations and Warranties............................................... 38
                  12.3     Qualifications....................................................................... 38
                  12.4     Legal Matters........................................................................ 39

         ARTICLE 13        MISCELLANEOUS........................................................................ 39
                  13.1     Governing Law........................................................................ 39
                  13.2     Survival............................................................................. 39
                  13.3     Successors and Assigns............................................................... 39
                  13.4     Entire Agreement; Amendment.......................................................... 39
                  13.5     Notices, etc......................................................................... 39
                  13.6     Delays or Omissions.................................................................. 40
                  13.7     California Corporate Securities Law.................................................. 40
                  13.8     Expenses............................................................................. 40

                                                  -iii-

<PAGE>



                  13.9     Remedies............................................................................. 40
                  13.10    Attorneys Fees....................................................................... 41
                  13.11    Counterparts......................................................................... 41
                  13.12    Severability......................................................................... 41
                  13.13    Titles and Subtitles................................................................. 41


</TABLE>

                                                   -iv-

<PAGE>



                            STOCK PURCHASE AGREEMENT


         THIS STOCK PURCHASE AGREEMENT (this "Agreement") is made as of June 24,
1996, by and between  IMATRON INC., a New Jersey  corporation  (the  "Imatron");
HEARTSCAN IMAGING, INC., a Delaware corporation ("HeartScan") and those entities
and  persons set forth on Exhibit A hereto  (individually,  a  "Purchaser,"  and
collectively the "Purchasers").

                                    ARTICLE 1

                           PURCHASE AND SALE OF SHARES

         1.1 Ownership of Shares. Imatron is the registered and beneficial owner
of 100,000 shares of HeartScan's Series A Preferred Stock (the "Shares").

         1.2 Sale and  Purchase  of the  Shares.  At the  Closing (as defined in
Section 2.1 hereof),  and in reliance upon the  representations,  warranties and
agreements  contained  herein,  Imatron  will  sell to each  Purchaser  and each
Purchaser  will  purchase from Imatron the number of Shares  specified  opposite
each Purchaser's  name on the Schedule of Purchasers  attached hereto as Exhibit
A, at a cash price of One Hundred  Sixty Dollars  ($160.00)  per Share.  As used
herein,  the term "Purchase  Price" shall mean the aggregate  purchase price for
the Shares payable by an individual Purchaser.

                                    ARTICLE 2

                             CLOSING DATE; DELIVERY

         2.1 Closing  Date.  The closing of the  purchase and sale of the Shares
hereunder  shall be held at the  offices of Severson & Werson,  One  Embarcadero
Center,  San Francisco,  California  94111 at 3:00 p.m., local time, on June 24,
1996 (the "Closing") or at such other time and place as shall be mutually agreed
upon by  Imatron  and the  Purchasers  (the  date of the  Closing  is  hereafter
referred to as the "Closing Date").

         2.2 Delivery.  At the Closing,  Imatron will deliver to each  Purchaser
certificates  for the  number of Shares  set forth  opposite  its name under the
heading  "Shares"  registered  in  such  Purchaser's  name on  Exhibit  A, or in
accordance with such Purchaser's  instructions,  and each Purchaser will deliver
to Imatron by check or wire  transfer to Imatron's  account the amount set forth
opposite each Purchaser's name on Exhibit A.

                                    ARTICLE 3

                    REPRESENTATIONS AND WARRANTIES OF IMATRON

         Except as set forth on the Schedule of  Exceptions  attached  hereto as
Exhibit B, Imatron represents and warrants to the Purchasers as follows:


<PAGE>




         3.1  Ownership  and Title.  Imatron is the owner,  beneficially  and of
record, of all of the Shares free and clear of all liens, encumbrances, security
agreements,  equities, options, claims, charges and restrictions. The Shares are
not  subject to any  restrictions  with  respect to  transferability,  except as
provided  under the  Securities  Act of 1933 (the  "Securities  Act").  Upon the
transfer and delivery of the Shares to each Purchaser hereunder,  such Purchaser
will receive  good and absolute  title  thereto,  free from all liens,  charges,
encumbrances,  equities,  restrictive agreements and claims whatsoever except as
specifically provided herein.

         3.2 Organization and Standing.  Imatron is a corporation duly organized
and  validly  existing  under,  and by virtue  of,  the laws of the State of New
Jersey and is in good standing under such laws.  HeartScan is a corporation duly
organized and validly existing under, and by virtue of, the laws of the State of
Delaware and is in good standing  under such laws.  Imatron and  HeartScan  each
have all  requisite  corporate  power and  authority  to own and  operate  their
respective properties and assets, and to carry on their respective businesses as
presently  conducted and as proposed to be conducted.  Imatron and HeartScan are
qualified  and are in good  standing  in each  foreign  jurisdiction  where such
qualification is required.

         3.3 Corporate  Power.  Imatron and HeartScan  each have or will have at
the Closing  Date all  requisite  legal and  corporate  power and  authority  to
execute and deliver this  Agreement  and to sell and issue the Shares  hereunder
and to carry out and perform its and their  obligations  under the terms of this
Agreement.

         3.4  Subsidiaries.  Except  as set  forth on  Exhibit  B,  Imatron  and
HeartScan have no subsidiaries or affiliated  companies and do not otherwise own
or control,  directly or  indirectly,  any equity  interest in any  corporation,
association or business entity.

         3.5      Capitalization.

                  (a)  Capitalization  of  Imatron.  At the  Closing  Date,  the
authorized  capital stock of Imatron will consist of: (i) 100,000,000  shares of
Common Stock,  of which  76,268,990  shares were issued and  outstanding  and of
which  3,722,560  shares  have been  reserved  for  issuance  under  outstanding
warrants,  6,648,209  shares of which  have been  reserved  for  issuance  under
various option and stock purchase plans;  1,500,000 shares of which are reserved
for issuance under an effective  registration on Form S-3; and 10,666,667 shares
of which have been reserved for exchange hereunder; and (ii) 5,000,000 shares of
preferred stock of which 500,000 shares have been designated "Series A Preferred
Stock" none of which are issued and outstanding and 500,000 shares of which have
been  designated  "Series  B  Preferred  Stock"  none of which  are  issued  and
outstanding.  Imatron's  capitalization is summarized as set forth on Exhibit C.
The  outstanding  shares of Common Stock have been duly  authorized  and validly
issued, and are fully paid and nonassessable. The shares of Imatron Common Stock
are not subject to any preemptive rights or rights of first refusal.

                  (b)  Capitalization  of HeartScan.  At the Closing  Date,  the
authorized  capital stock of HeartScan will consist of: (i) 4,000,000  shares of
Common Stock, of which 21,094

                                       -2-

<PAGE>



will be issued and  outstanding  and of which 448,906  shares have been reserved
for issuance  pursuant to stock option and other plans,  30,000 shares have been
reserved for issuance  upon the exercise of warrants to be issued in  connection
with the purchase  and sale of the Shares,  and  2,000,000  shares of which have
been  reserved  for  issuance  upon  conversion  of the  Shares and the Series B
Preferred  Stock,  and (ii) 1,000,000 shares of preferred stock of which 200,000
shares have been designated  "Series A Preferred Stock" and of which 100,000 are
issued and outstanding and 100,000 shares of which have been designated  "Series
B  Preferred  Stock" and of which  100,000  shares  are issued and  outstanding.
HeartScan's  capitalization  is  summarized  as set  forth  on  Exhibit  C.  The
outstanding  shares of Series A Preferred and Series B Preferred  have been duly
authorized and validly issued, and are fully paid and  nonassessable.  Except as
provided  herein and as set forth in Exhibit B, the shares of  HeartScan  Common
Stock,  Series  A  Preferred  and  Series B  Preferred  are not  subject  to any
preemptive  rights or rights of first refusal.  The  Certificates of Designation
pertaining to HeartScan's Series A Preferred and Series B Preferred are attached
hereto as Exhibit D.

         3.6  Authorization.  All  corporate  action on the part of Imatron  and
HeartScan,  its directors  and  shareholders  necessary  for the  authorization,
execution,  delivery and performance of this Agreement by Imatron and HeartScan,
the sale and delivery of the Shares and the  performance of all of Imatron's and
HeartScan's obligations hereunder and thereunder has been taken or will be taken
prior to the Closing.  This Agreement when executed and delivered by Imatron and
HeartScan,  shall constitute valid and binding obligations of each,  enforceable
in accordance with its terms, subject to laws of general application relating to
bankruptcy,  insolvency  and the  relief of debtors  and rules of law  governing
specific  performance,  injunctive relief or other equitable remedies and except
to the extent  that  Sections  9.6 and 10.7 may be limited by public  policy and
applicable  judicial  decisions.  The Shares are validly issued,  fully paid and
nonassessable  and in all such cases will be free of  restrictions  on  transfer
other than transfer under this  Agreement and applicable  state and federal laws
and when the Shares have been  converted or exchanged in  accordance  with their
terms,  the HeartScan  Common Stock issuable upon  conversion and Imatron Common
Stock issuable upon exchange,  as the case may be, will be validly issued, fully
paid and non-assessable.

         3.7 Financial  Statements.  Imatron has delivered to the Purchasers the
following financial statements (the "Financial Statements"):

                  (i) Imatron's audited consolidated balance sheet, statement of
operations,  statement of stockholders' equity and statement of cash flows as of
and for the year ended December 31, 1995;

                  (ii)   Imatron's   unaudited   consolidating   balance  sheet,
statement of operations, statement of stockholders' equity and statement of cash
flows as of and for the year ended December 31, 1995; and

                  (iii)  Imatron's   unaudited   consolidating   balance  sheet,
statement of operations, statement of stockholders' equity and statement of cash
flows as of and for the three months

                                       -3-

<PAGE>



ended March 31, 1996.

         The  Financial  Statements  are  complete  and correct in all  material
respects and have been prepared in accordance with generally accepted accounting
principles,  except  that the  unaudited  Financial  Statements  do not  contain
footnotes normally required by generally  accepted  accounting  principles.  The
Financial Statements accurately set out and describe the financial condition and
operating  results  of Imatron  and  HeartScan  as of the dates,  and during the
periods,  indicated therein.  Except as disclosed in the Financial Statements or
in Exhibit B, neither  Imatron nor HeartScan is a guarantor or indemnitor of any
indebtedness  of any other person,  firm or  corporation.  Imatron and HeartScan
maintain  and  will  continue  to  maintain  a  standard  system  of  accounting
established and  administered in accordance with generally  accepted  accounting
principles.

         3.8 Absence of Undisclosed Liabilities. To the best of their knowledge,
neither  Imatron nor  HeartScan  has any debt,  liability,  or obligation of any
nature, whether accrued, absolute,  contingent, or otherwise, and whether due or
to become due, that is not reflected or reserved against in Financial Statements
or as set forth in  Exhibit B to this  Agreement,  except for (1) those that may
have been  incurred  after March 31, 1996 and (2) those that are not required by
generally  accepted  accounting  principles  to be included  in a balance  sheet
(including the notes thereto). All debts, liabilities,  and obligations incurred
after that date were  incurred in the ordinary  course of business and are usual
and normal in amount both individually and in the aggregate.

         3.9      Changes.  Since December 31, 1995, there has not been:

                  (a) any change in the assets, liabilities, financial condition
or  operating  results  of  Imatron  or  HeartScan  from that  reflected  in the
Financial  Statements,  except  changes in the ordinary  course of business that
have not been, in the aggregate, materially adverse;

                  (b) any damage, destruction or loss, whether or not covered by
insurance, materially and adversely affecting the assets, properties,  financial
condition,  operating results, prospects or business of Imatron or HeartScan (as
such  businesses  is  presently  conducted  and  as  they  are  proposed  to  be
conducted);

                  (c) any waiver by Imatron or HeartScan of a valuable  right or
of a material debt owed to either;

                  (d) any  satisfaction  or  discharge  of any  lien,  claim  or
encumbrance or payment of any obligation by Imatron or HeartScan,  except in the
ordinary  course of  business  consistent  with prior  practice  and that is not
material to the assets,  properties,  financial condition,  operating results or
business of either (as such  businesses are presently  conducted and as they are
proposed to be conducted);

                  (e) any material change or amendment to a material contract or
arrangement

                                       -4-

<PAGE>



by which  Imatron or HeartScan or any of their  respective  assets or properties
are bound or are subject;

                  (f) any material  change in any  compensation  arrangement  or
agreement with any employee;

                  (g)  any  sale,   assignment   or  transfer  of  any  patents,
trademarks, copyrights, trade secrets or other intangible assets;

                  (h) any  resignation  or  termination of employment of any key
officer of Imatron or HeartScan;  and neither Imatron nor HeartScan, to the best
of  their  knowledge,  know  of the  impending  resignation  or  termination  of
employment of any such officer;

                  (i)  receipt  of  notice  that  there  has been a loss of,  or
material order cancellation by, any major customer of Imatron or HeartScan;

                  (j) any mortgage,  pledge, transfer of a security interest in,
or lien, created by Imatron or HeartScan,  with respect to any of their material
properties or assets, except liens for taxes not yet due or payable;

                  (k)  any  declaration,  setting  aside  or  payment  or  other
distribution  in respect of any of  Imatron's  capital  stock,  or any direct or
indirect  redemption,  purchase  or other  acquisition  of any of such  stock by
Imatron;

                  (l) to the best of  Imatron's  knowledge,  any other  event or
condition  of any  character  that might  materially  and  adversely  affect the
assets,  properties,  financial  condition,  operating  results or  business  of
Imatron (as such  business is  presently  conducted  and as it is proposed to be
conducted); or

                  (m) any  agreement or  commitment  by Imatron to do any of the
things described in this Section 3.9.

         3.10 Title to Assets;  Liens, etc. Except as disclosed in the Financial
Statements,  Imatron  and  HeartScan  have  good and  marketable  title to their
respective  assets  and have  good  title to all of their  respective  leasehold
interests, in each case subject to no mortgage, pledge, lien, lease, encumbrance
or charge, other than (i) the lien of current taxes not yet due and payable, and
(ii) possible minor liens and  encumbrances  which do not in any case materially
detract from the value of the property subject thereto or materially  impair the
operations of Imatron or HeartScan,  and which have not arisen otherwise than in
the ordinary course of business.

         3.11 Compliance with other Instruments, None Burdensome, etc. Except as
set forth in Exhibit B, neither  Imatron nor  HeartScan  are in violation of any
term of their respective Articles of Incorporation or Bylaws, or in any material
respect of any term or provision of any

                                       -5-

<PAGE>



mortgage, indebtedness,  indenture, contract, agreement, instrument, judgment or
decree, and to their knowledge are not in violation of any order,  statute, rule
or regulation  applicable  to Imatron or HeartScan  where such  violation  would
materially and adversely affect either. The execution,  delivery and performance
of and  compliance  with this  Agreement and the transfer and sale of the Shares
have not resulted and will not result in any violation of, or conflict  with, or
constitute a default  under,  Imatron's or  HeartScan's  respective  Articles of
Incorporation or Bylaws or any of their agreements or result in the creation of,
any mortgage,  pledge, lien, encumbrance or charge upon any of the properties or
assets of  Imatron  or  HeartScan  or the  suspension,  revocation,  impairment,
forfeiture,  or nonrenewal of any material permit,  license,  authorization,  or
approval  applicable  either,  their  businesses  or  operations or any of their
assets or properties, and there is no such violation or default which materially
and  adversely  affects  the  business of Imatron or  HeartScan  or any of their
material properties or assets.

         3.12  Intellectual  Property.  Except as set forth in Exhibit B, to the
best of their  knowledge,  Imatron  and  HeartScan  have  sufficient  title  and
ownership of all franchises,  permits, licenses,  trademarks,  trademark rights,
copyrights,  service marks,  trade names, trade secrets,  know-how  information,
proprietary rights and processes,  and other similar authority necessary for the
conduct of their  businesses as now conducted and as proposed to be conducted by
them  (collectively,  the "Intellectual  Property") without any conflict with or
infringement  of the rights of  others.  Neither  Imatron  nor  HeartScan  is in
violation,  nor will the  transaction  contemplated  by this  Agreement  cause a
violation of the terms or provisions of any franchises,  permits, or licenses to
which  either is a party.  There is  neither  pending,  nor,  to  Imatron's  and
HeartScan's  knowledge,  threatened,  any claim or litigation against Imatron or
HeartScan  contesting  the  validity  or  right  to use any of the  Intellectual
Property.  To Imatron's and  HeartScan's  knowledge,  no person,  corporation or
other  entity  is  infringing  the  Intellectual   Property.  To  Imatron's  and
HeartScan's  knowledge,  neither  Imatron nor  HeartScan is currently  using the
confidential  information or trade secrets of any person without the consent of,
or a grant of a license or other right to use such information or trade secrets,
from such other person or entity.

         3.13  Litigation,   etc.  There  is  no  action,  suit,  proceeding  or
investigation   pending  against  Imatron  or  HeartScan  or  their   respective
properties  before any court or  governmental  agency  (nor,  to  Imatron's  and
HeartScan's knowledge, is there any reasonable basis therefor or threat thereof)
that  questions  the  validity  of this  Agreement,  or the right of Imatron and
HeartScan  to enter  into such  agreement,  or to  consummate  the  transactions
contemplated hereby or thereby, or that might result,  either individually or in
the aggregate, in any material adverse changes in the assets, condition, affairs
or prospects of Imatron or HeartScan, financially or otherwise, or any change in
the  current  equity  ownership  of Imatron  or  HeartScan,  nor are  Imatron or
HeartScan  aware that there is any basis for the foregoing.  Neither Imatron nor
HeartScan  is a  party  or  subject  to  the  provisions  of  any  order,  writ,
injunction,   judgment  or  decree  of  any  court  or   government   agency  or
instrumentality.

         3.14 Employees.  To the best of Imatron's and HeartScan's knowledge, no
employee of Imatron or  HeartScan is obligated  under,  or in violation  of, any
employment  contract  or any other  contract  or  agreement,  or  subject to any
judgment, decree or order of any court or

                                       -6-

<PAGE>



administrative  agency,  that  would  interfere  with the use of his or her best
efforts to promote the interests of Imatron or HeartScan or would  conflict with
either's businesses.  Neither the execution nor delivery of this Agreement,  nor
the  carrying  on of  Imatron's  business  by the  employees  of  Imatron or the
carrying on of HeartScan's business by the employees of HeartScan,  will, to the
best of Imatron's and HeartScan's knowledge, conflict with or result in a breach
of the terms,  conditions or provisions of, or constitute a default  under,  any
contract,  covenant  or  instrument  under  which any of such  employees  is now
obligated.

         3.15 Registration  Rights.  Except as set forth herein and in Exhibit B
hereto,  HeartScan  is not under any  contractual  obligation  to  register  (as
defined in Section 9.1(f)) any of its presently outstanding securities or any of
its securities which may hereafter be issued.

         3.16 Governmental Consent,  etc. No consent,  approval or authorization
of or designation,  declaration or filing with any governmental authority on the
part of Imatron or HeartScan is required in connection  with the valid execution
and  delivery  of this  Agreement,  or the offer or sale of the  Shares,  or the
consummation of any other transaction  contemplated hereby, except qualification
(or  taking  such  action  as may be  necessary  to  secure  an  exemption  from
qualification,  if  available)  of the  offer and sale of the  Shares  under the
California  Corporate  Securities Law of 1968, as amended,  and other applicable
Blue  Sky  laws,  which  filings  and  qualifications,   if  required,  will  be
accomplished in a timely manner.

         3.17   Offering.   Subject   to  the   accuracy   of  the   Purchaser's
representations  in  Section  4  hereof,  the  offer  and sale of the  Shares in
accordance  with the terms of this  Agreement  constitutes a transaction  exempt
from the  registration  requirements  of Section 5 of the Securities Act of 1933
(the  "Securities  Act"),  and neither  Imatron nor HeartScan nor any authorized
agent acting on their behalf will take any action hereafter that would cause the
loss of such exemption.

         3.18 Material Contracts.  Except as set forth in Exhibit B, Imatron and
HeartScan are in compliance with all of the material  obligations  under each of
the material contracts to which Imatron and HeartScan are parties, including but
not limited to Imatron's agreements with Siemens Corporation or its affiliates.

         3.19  Licenses;  Compliance  with Laws.  Imatron and HeartScan have all
local, state,  federal and foreign operating  authority,  licenses,  franchises,
permits,  certificates,  consents,  rights and privileges and similar  authority
(collectively,  "Licenses")  that  are  necessary  to  the  operation  of  their
businesses as now  conducted  and Imatron and HeartScan  believe they can obtain
any  similar  Licenses  for the  conduct  of their  businesses  as planned to be
conducted.  Such Licenses are in full force and effect,  no violations have been
or are expected to be recorded in respect of any Licenses,  and no proceeding is
pending or, to the  knowledge  of Imatron or  HeartScan,  threatened  that could
result in the  revocation  or limitation  of any such  Licenses.  To the best of
their  knowledge,  the businesses of Imatron and HeartScan have been and are now
being  conducted in material  compliance with all applicable  laws,  ordinances,
regulations,  orders  and  decrees.  Imatron  and  HeartScan  know of no audits,
investigations,  inquiries,  or  requests  for  information  relating  to  their
respective businesses, products or facilities claiming any

                                       -7-

<PAGE>



violation of any laws, such laws ordinances, regulations, orders and decrees. To
the best of their knowledge,  Imatron and HeartScan  believe that their products
and  services  are  in  material   compliance  with  all  applicable  rules  and
regulations promulgated by the United States Food and Drug Administration and by
the State of California Department of Health Services, Food and Drug Branch.

         3.20  Disclosure.  Imatron  and  HeartScan  have  fully  provided  each
Purchaser with an opportunity to have answered  questions of officers of Imatron
and HeartScan.  The information provided to the Purchaser in connection with the
transactions  contemplated  by this  Agreement,  when  taken  together,  did not
contain  (or will not  contain on the  Closing  Date) an untrue  statement  of a
material fact and did not omit (or will not omit on the Closing Date) to state a
material fact required to make the statements  therein,  when viewed together in
light of the circumstances under which they were made, not false or misleading.

         3.21  Environmental  and Safety Laws.  To the best of their  knowledge,
Imatron and HeartScan  are not in violation of any  applicable  statute,  law or
regulation relating to the environment or occupational health and safety, and to
the best of their knowledge, no material expenditures are or will be required in
order to comply with any such existing statute, law or regulation.

         3.22 Imatron  Corporate  Documents.  The Articles of Incorporation  and
Bylaws of  Imatron  are in the forms  previously  provided  to  counsel  for the
Purchasers.

         3.23 HeartScan Corporate  Documents.  The Articles of Incorporation and
Bylaws of  HeartScan  are in the form  previously  provided  to counsel  for the
Purchasers,  except that the  Certificates  of  Determination  of Preferences of
HeartScan's Series A Preferred Stock and Series B Preferred Stock will be as set
forth in Exhibit D hereto.

         3.24 Insurance. Imatron has in full force and effect fire and casualty,
professional  liability and product liability insurance policies,  with extended
coverage,  sufficient in amount (subject to reasonable  deductibles) to allow it
to replace any of its properties that might be damaged or destroyed.

         3.25 Labor  Agreements  and Actions.  Neither  Imatron nor HeartScan is
bound by or subject to (and none of their  respective  assets or  properties  is
bound by or subject  to) any  written or oral,  express  or  implied,  contract,
commitment or arrangement with any labor union, and no labor union has requested
or, to the best of  Imatron's  knowledge,  has  sought to  represent  any of the
employees, representatives or agents of Imatron or HeartScan. There is no strike
or other labor dispute involving Imatron or HeartScan pending, or to the best of
Imatron's  and  HeartScan's  knowledge,  threatened,  that could have a material
adverse  effect  on  the  assets,  properties,  financial  condition,  operating
results,  or business of either (as such businesses are presently  conducted and
as proposed to be  conducted),  nor are Imatron or HeartScan  aware of any labor
organization  activity  involving its  employees.  Imatron and HeartScan are not
aware that any  officer  or key  employee,  or that any group of key  employees,
intends to terminate their

                                       -8-

<PAGE>



employment  with  either  Imatron or  HeartScan.  To the best of its  knowledge,
Imatron and HeartScan have complied in all material respects with all applicable
state and  federal  equal  employment  opportunity  and other  laws  related  to
employment.

         3.26 Brokers or Finders.  Imatron and HeartScan have not, and will not,
incur,  directly  or  indirectly,  as a result of any action  taken by either of
them, any liability for brokerage or finders' fees or agents' commissions or any
similar charges in connection with this Agreement except for fees due to Ambient
Capital Group,  Inc.,  Libra  Investments,  Inc.,  The Shemano  Group,  Inc. and
Heritage Trust and Finance which fees shall be paid by Imatron and/or HeartScan.

                                    ARTICLE 4

                REPRESENTATIONS AND WARRANTIES OF THE PURCHASERS

         Each  Purchaser  hereby  represents  and  warrants,  severally  and not
jointly,  to Imatron and  HeartScan  with respect to the purchase of the Shares,
the exchange rights as provided in Article 5 hereof (the "Exchange  Rights") and
the shares of Imatron Common Stock issuable upon exercise of the Exchange Rights
(the "Imatron Exchange Shares") (the Shares, the Exchange Rights and the Imatron
Exchange   Shares  are   collectively   referred  to  in  this  Article  as  the
"Securities") by such Purchaser as follows:

         4.1 Risk.  The  Purchaser  is aware that  investments  in  Imatron  and
HeartScan are highly  speculative and that there can be no assurance as to what,
if any,  return that there may be on the  Purchaser's  investment in the Shares,
the Exchange  Rights and the Imatron  Exchange  Common  Stock.  The Purchaser is
aware of Imatron's and HeartScan's  business affairs and financial condition and
has acquired  sufficient  information  about Imatron and HeartScan to be able to
evaluate  the  risks  and  merits  of the  proposed  investment  and to reach an
informed and knowledgeable decision to acquire the Securities.

         4.2 Experience. The Purchaser is an "Accredited Investor" as defined in
Regulation D under the Securities Act. The Purchaser has substantial  experience
in evaluating and investing in private  placement  transactions of securities in
companies  similar to Imatron and  HeartScan so that the Purchaser is capable of
evaluating  the merits and risks of its  investment in Imatron and HeartScan and
has the  capacity to protect  its own  interests.  If other than an  individual,
unless  Purchaser has  previously  advised  Imatron in writing,  Purchaser  also
represents it has not been organized for the purpose of acquiring the Securities
offered hereby.

         4.3 Principal  Place of Business.  The  Purchaser's  principal place of
business,  or if an individual his or her  residence,  is located at the address
indicated in Exhibit A hereto.

         4.4   Investment.   The  Purchaser  is  acquiring  the  Securities  for
investment for its own account, not as a nominee or agent, and not with the view
to, or for public resale in connection with, any distribution thereof other than
pursuant to a registration as contemplated hereby. The

                                       -9-

<PAGE>



Purchaser  understands  that the Shares and the Exchange  Rights,  have not been
registered  under the Securities Act by reason of a specific  exemption from the
registration provisions of the Securities Act, the availability of which depends
upon, among other things,  the bona fide nature of the investment intent and the
accuracy of such Purchaser's representations as expressed herein.

         4.5 Rule  144.  The  Purchaser  acknowledges  that the  Securities  are
characterized as "restricted  securities" under the federal  securities laws and
must be held indefinitely  unless  subsequently  registered under the Securities
Act or unless an exemption from such registration is available. The Purchaser is
aware of the provisions of Rule 144  promulgated  under the Securities Act which
permits limited public resale of shares purchased in a private placement subject
to the satisfaction of certain  conditions,  including,  among other things, the
existence of a public market for the shares, the availability of certain current
public  information  about the issuer,  the resale  occurring  not less than two
years after a party has purchased and paid for the security to be sold, the sale
being effected through a "broker's transaction" or in transactions directly with
a "market  maker" and the number of shares  being  sold  during any  three-month
period not exceeding specified limitations.

         4.6 No Public Market.  The Purchaser  understands that no public market
now exists for any of the securities  issued by HeartScan and that HeartScan has
made no  assurances  that a  public  market  will  ever  exist  for  HeartScan's
securities.

         4.7 Access to Data.  The  Purchaser has had an  opportunity  to discuss
Imatron's  and  HeartScan's  respective  businesses,  managements  and financial
affairs with their  managements  and the  opportunity  to review  Imatron's  and
HeartScan's  facilities  and  financial  data.  The  Purchaser  has  also had an
opportunity  to ask  questions  of  officers  of Imatron  and  HeartScan,  which
questions were answered to its, his or her satisfaction. The foregoing, however,
does not limit or modify  the  representations  and  warranties  of  Imatron  in
Section 3 of this Agreement or the right of Purchaser to rely thereon.

         4.8  Authorization.  This  Agreement when executed and delivered by the
Purchaser  will  constitute  a  valid  and  legally  binding  obligation  of the
Purchaser,  enforceable in accordance with its terms, subject to laws of general
application  relating to  bankruptcy,  insolvency  and the relief of debtors and
rules  of  law  governing  specific  performance,  injunctive  relief  or  other
equitable remedies.

         4.9 Brokers or Finders.  Each Purchaser  represents that such Purchaser
has  dealt  with  no  broker  or  finder  in  connection  with  any  transaction
contemplated  by  this  agreement,   except  for  Ambient  Group,   Inc.,  Libra
Investments,  Inc., The Shemano Group, Inc. or Heritage Trust and Finance;  and,
as far as such  Purchaser it knows,  no other broker or other person is entitled
to any commission or finder's fee in connection with this Agreement.

         4.10 Investor Counsel;  Investment Advisor. The Purchaser  acknowledges
that it has had the opportunity to review this  Agreement,  the exhibits and the
schedules attached hereto and

                                      -10-

<PAGE>



the transactions  contemplated by this Agreement with its own legal counsel. The
Purchaser  is  relying  solely  on such  counsel  and not on any  statements  or
representations  of  Imatron,  HeartScan,  or any of their  agents  for legal or
investment   advice  with  respect  to  this  investment  or  the   transactions
contemplated by this Agreement.


                                    ARTICLE 5

                                 EXCHANGE RIGHTS

         5.1 Certain  Definitions.  As used in this Section, the following terms
shall have the following respective meanings:

                  (a) "First Exchange  Period" shall mean the period  commencing
on the  Closing  Date and ending on the  earlier to occur of (i) two years after
June 26, 1996, or (ii) the IPO Date.

                  (b) "Second  Exchange Period" shall mean the five business (5)
day period following each Pricing Date.

                  (c) "Qualified  Public  Offering" shall mean an initial public
offering  of  the  HeartScan's  common  stock  to  the  general  public  with  a
post-offering,  pre-proceeds  valuation of the existing  equity at June 26, 1996
(such equity  consisting of 100,000  issued and  outstanding  shares of Series A
Preferred,  100,000 issued and outstanding shares of Series B Preferred,  21,094
shares of issued and  outstanding  Common Stock and 448,906  reserved  shares of
Common Stock) of no less than  $56,000,000 for an initial public offering during
the first year  following June 26, 1996 and of no less than  $78,000,000  for an
initial  public  offering  during the second  year  following  June 26, 1996 and
resulting in aggregate net proceeds of not less than $15,000,000,  which initial
public offering is effected pursuant to a registration statement filed with, and
declared  effective  by,  the  Securities  and  Exchange  Commission  under  the
Securities Act.

                  (d) "IPO Date"  shall  mean the  closing  date of a  Qualified
Public Offering.

                  (e) "Imatron Exchange Shares" shall mean the shares of Imatron
Common Stock issuable  pursuant to the exchange rights set forth in Sections 5.2
and 5.3 hereof and all shares of Imatron Common Stock issued pursuant hereto.

                  (f) "Pricing  Date" shall mean each of the second  anniversary
of June 26, 1996 and each date that is three months  thereafter  to an including
the fourth anniversary of June 26, 1996.

         5.2      First Exchange Period Rights.


                                      -11-

<PAGE>



                  (a) Exchange  Rights.  Each share of Series A Preferred may be
exchanged  at the  option  of  the  Purchaser,  without  payment  of  additional
consideration  at any  time  during  the  First  Exchange  Period  at  Imatron's
corporate  office or any transfer  agent for Imatron's  Common  Stock,  for such
number of validly issued,  fully paid and nonassessable shares of Imatron Common
Stock,  as is determined by dividing One Hundred Sixty Dollars  ($160.00) by the
First Period Exchange Price,  determined as hereinafter  provided,  in effect at
the time of  exchange.  The  price at which  shares  of  Common  Stock  shall be
deliverable upon exchange (the "First Period Exchange Price") shall initially be
Five  Dollars  ($5.00)  per share of Common  Stock (the  "Initial  First  Period
Exchange  Price").  The initial First Period  Exchange Price shall be subject to
adjustment as hereinafter provided.

                  (b) Adjustments for Subdivisions,  Dividends,  Combinations or
Consolidations of Imatron Common Stock.

                           (1) In the event the  outstanding  shares of  Imatron
Common Stock shall be combined,  consolidated or subdivided, by reclassification
or otherwise,  into a lesser number of shares of Imatron Common Stock, the First
Period  Exchange  Price  in  effect  immediately  prior to such  combination  or
consolidation shall,  concurrently with the effectiveness of such combination or
consolidation, be proportionately increased.

                           (2) In the event  Imatron  shall  declare  or pay any
dividend on the Imatron  Common Stock payable in Imatron  Common Stock or in the
event the  outstanding  shares of Imatron Common Stock shall be  subdivided,  by
reclassification  or otherwise  than by payment of a dividend in Imatron  Common
Stock, into a greater number of shares of Imatron Common Stock, the First Period
Exchange Price in effect immediately prior to such dividend or subdivision shall
be proportionately decreased:

                                    (i)  in  the  case  of  any  such  dividend,
immediately after the close of business on the record date for the determination
of holders of any class of securities entitled to receive such dividend, or

                                    (ii) in the case of any such subdivision, at
the close of business on the date immediately  prior to the date upon which such
corporate action becomes effective.

         If such record date shall have been fixed and such  dividend  shall not
have been fully paid on the date fixed therefor,  the adjustment previously made
in the First Period  Exchange  Price which became  effective on such record date
shall be  cancelled  as of the  close  of  business  on such  record  date,  and
thereafter  the First Period  Exchange Price shall be adjusted as of the time of
actual payment of such dividend.

                  (c) Termination.  The exchange rights pursuant to this Section
5.2 shall  terminate upon the earlier of (i) the IPO Date,  (ii) four years from
June 26, 1996; or (iii) upon conversion of the Shares.


                                      -12-

<PAGE>



                  (d)  Reorganization,   Consolidation,  Merger,  etc.  In  case
Imatron  after  the  Closing  Date  shall  (a)  effect  a  reorganization,   (b)
consolidate  with or  merge  into  any  other  entity,  or (c)  transfer  all or
substantially all of its properties or assets to any other entity, then, in each
such case,  the  Purchaser,  upon the exercise of the exchange  rights  provided
herein, at any time after the consummation of such reorganization, consolidation
or merger or the effective date of such dissolution,  as the case may be, during
the First  Exchange  Period shall be entitled to receive  (and Imatron  shall be
required to deliver), in lieu of the Imatron Common Stock issuable upon exercise
of the  exchange  rights  as  provided  in  Section  5.2,  the  stock  and other
securities and property (including cash) to which such Purchaser would have been
entitled upon such consummation or in connection with such  dissolution,  as the
case may be, if such Purchaser had exchanged the Shares to such extent.

                  (e) Certificate as to Adjustments. Upon the occurrence of each
adjustment  or  readjustment  of the First  Period  Exchange  Price  Pursuant to
Section  5.2(b) or (c),  Imatron at its  expense  shall  promptly  compute  such
adjustment or  readjustment  in accordance  with the terms hereof and furnish to
each Purchaser of Series A Preferred as appropriate a certificate  setting forth
such adjustment or readjustment  and showing in detail the facts upon which such
adjustment or readjustment is based.  Imatron shall, upon the written request at
any  time of any  Purchaser  of  Series  A  Preferred,  furnish  or  cause to be
furnished  to  such  Purchaser  a  like  certificate   setting  forth  (i)  such
adjustments and readjustments,  (ii) the First Period Exchange Price at the time
in  effect,  and (iii) the  number of  shares of  Imatron  Common  Stock and the
amount,  if any, of other  property which at the time would be received upon the
exchange of Series A Preferred.

         5.3      Second Exchange Period Rights.

                  (a) Exchange  Rights.  Each share of Series A Preferred may be
exchanged  at the  option  of  the  Purchaser,  without  payment  of  additional
consideration  at any time during  each Second  Exchange  Period,  at  Imatron's
corporate  office or any transfer  agent for Imatron's  Common  Stock,  for such
number of validly issued,  fully paid and nonassessable shares of Imatron Common
Stock,  as is determined by dividing One Hundred Sixty Dollars  ($160.00) by the
applicable  Second Period Exchange Price. The Second Period Exchange Price is an
amount  equal to  seventy-three  percent  (73%)  of the  average  closing  price
(rounded to the nearest cent) of a share of Imatron's Common Stock,  weighted by
volume,  as reported in The Wall Street  Journal on each  trading  date on which
such shares are traded during the ninety (90) day period  immediately  preceding
each  Pricing  Date,  but in no event  shall  such 73% be less than  $1.50  (the
"Second  Exchange  Period Floor Price").  The Second Exchange Period Floor Price
shall  be  subject  to  appropriate  adjustment  in the  event  of  subdivision,
dividends, combination or consolidation of Imatron Common Stock. On each Pricing
Date Imatron  shall advise the  Purchasers  of the  applicable  Second  Exchange
Period Price.

                  (b) Termination.  The exchange rights pursuant to this Section
5.3 shall  terminate  upon the earlier of (i) the IPO Date,  (ii) five  business
days after the fourth  anniversary of June 26, 1996; or (iii) upon conversion of
the Shares.

                                      -13-

<PAGE>




                  (c) Adjustments for Subdivisions,  Dividends,  Combinations or
Consolidations  of Series A Preferred  Stock.  In the event the Shares  shall be
combined,  consolidated or subdivided by reclassification  or otherwise,  into a
lesser or greater  number of shares of Series A  Preferred,  the  Second  Period
Exchange  Price shall be  proportionately  increased or decreased  such that the
aggregate  value of all Series A Preferred  Shares into which the Second  Period
Exchange  Price is divided to determine  the exchange  rate shall be not greater
than $16,000,000.

                  (d)  Reorganization,   Consolidation,  Merger,  etc.  In  case
Imatron  after  the  Closing  Date  shall  (a)  effect  a  reorganization,   (b)
consolidate  with or  merge  into  any  other  entity,  or (c)  transfer  all or
substantially all of its properties or assets to any other entity, then, in each
such  case,  the  Purchaser,  upon the  exercise  hereof,  at any time after the
consummation of such  reorganization,  consolidation  or merger or the effective
date of such dissolution,  as the case may be, during the Second Exchange Period
shall be entitled to receive (and Imatron shall be required to deliver), in lieu
of the Imatron  Common Stock  issuable upon  exercise of the exchange  rights as
provided in Section 5.3, the stock and other securities and property  (including
cash) to which such Purchaser would have been entitled upon such consummation if
such Purchaser had so exchanged the Shares to such extent.

         5.4 No Impairment. Imatron will not, by amendment of its Certificate of
Incorporation or through any reorganization,  transfer of assets, consolidation,
merger, dissolution,  issue or sale of securities or any other voluntary action,
avoid or seek to avoid the  observance or  performance of any of the terms to be
observed or  performed  hereunder by Imatron but will at all times in good faith
assist in the  carrying out of all the  provisions  of this Article 5 and in the
taking of all such action as may be necessary or appropriate in order to protect
the Exchange Rights of the holders of the Series A Preferred against impairment.

         5.5 Mechanics of Exchange. No fractional shares of Imatron Common Stock
shall be issued upon exchange of Series A Preferred.  In lieu of any  fractional
shares to which the holder would  otherwise be entitled,  Imatron shall pay cash
equal to such fraction  multiplied by the then effective Exchange Price.  Before
any holder of Series A Preferred  shall be  entitled  to exchange  the same into
full shares of Imatron  Common  Stock,  it shall  surrender  the  certificate(s)
therefor,  duly endorsed,  at the office of Imatron or of any transfer agent for
Imatron Common Stock together with any dividends or other distributions in cash,
securities or in kind which the Purchaser has received or is entitled to receive
from the date of  issuance  of the Series A  Preferred  to the date of  exchange
(except for shares  purchased  pursuant to Section 5.7),  and shall give written
notice to Imatron at such office that it elects to  exchange  the same.  Imatron
shall,  as soon as  practicable  thereafter  but in no event later than five (5)
business  days,  issue and  deliver  at such  office to such  holder of Series A
Preferred,  a  certificate(s),  registered  in such  names as  specified  by the
holder,  for the number of shares of Imatron  Common  Stock to which it shall be
entitled  as  aforesaid  and a check  payable to the holder in the amount of any
cash  amounts  payable  as the result of a exchange  into  fractional  shares of
Imatron Common Stock.  Imatron shall use its  reasonable  best efforts to effect
such issuance and delivery  within three (3) business days.  Such exchange shall
be deemed to have been made  immediately  prior to the close of  business on the
date of such surrender of the shares of Series A Preferred to be converted,

                                      -14-

<PAGE>



and the person(s)  entitled to receive  shares of Imatron  Common Stock issuable
upon such exchange shall be treated for all purposes as the record  holder(s) of
such shares of Imatron Common Stock on such date.

         5.6  Reservation  of Imatron  Common Stock.  Imatron shall at all times
have reserved from its authorized and unissued Imatron Common Stock a sufficient
number of shares of Imatron  Common Stock to satisfy the exchange  rights of the
shares of Series A Preferred Stock.

         5.7 Participation Rights Offering. To the extent Imatron makes a rights
offering to all of its holders of Common Stock during the First Exchange  Period
and the Second Exchange  Period,  the holders of the Shares shall be offered the
right to  participate  in such  offering as if they had exchanged the Shares for
Imatron Common Stock.

         5.8 Notices of Record Date.  In the event that Imatron shall propose at
any time:

                  (a) to declare any dividend or  distribution  upon its Imatron
Common Stock, whether in cash, property,  stock or other securities,  whether or
not a  regular  cash  dividend  and  whether  or not out of  earnings  or earned
surplus;

                  (b) to offer for  subscription  pro rata to the holders of any
class or  series of its  stock  any  additional  shares of stock of any class or
series or other rights;

                  (c) to effect any  reclassification or recapitalization of its
Imatron Common Stock outstanding involving a change in the Imatron Common Stock;
or

                  (d)  to  merge  or   consolidate   with  or  into  any   other
corporation,  or sell, lease or convey all or substantially  all its property or
business,  or to liquidate,  dissolve or wind up; then, in connection  with each
such event, this corporation shall send to the holders of the Series A Preferred
shares:

                           (1) at least 30 days prior written notice of the date
on which a record shall be taken for such dividend, distribution or subscription
rights (and  specifying  the date on which the holders of Imatron  Common  Stock
shall be entitled  thereto) or for determining  rights to vote in respect of the
matters referred to in (c) and (d) above; and

                           (2) in the case of the matters referred to in (c) and
(d) above, at least 30 days prior written notice of the date when the same shall
take place (and specifying, if practicable,  or estimating the date on which the
holders of Series A  Preferred  shall be entitled  to  exchange  their  Series A
Preferred for  securities or other property  deliverable  upon the occurrence of
such event).

         Each such written  notice  shall be given by first class mail,  postage
prepaid,  addressed  to the  Purchasers  of Series A  Preferred  as  provided in
Article 13 hereof.


                                      -15-

<PAGE>



                                    ARTICLE 6

                              AFFIRMATIVE COVENANTS

         6.1 Use of Proceeds.  Imatron and HeartScan covenant and agree with the
Purchasers that the net proceeds from the sale of the Shares,  less all expenses
of the offering,  shall be used  generally as set forth in the Summary  Offering
Memorandum  (including the supplement  thereto) dated March 1996 and in no event
shall less than  $12,000,000  of such net proceeds be contributed to the capital
of HeartScan without additional consideration on the Closing Date.

         6.2 Right of  Participation.  HeartScan hereby grants to each Purchaser
the  right  of  participation  to  purchase,  pro  rata,  all or any part of New
Securities  (as defined in Section  6.2(a))  which  HeartScan  may, from time to
time, propose to sell and issue. A pro rata share, for purposes of this right of
participation, is the quotient obtained by dividing the sum of (x) the aggregate
number of shares of HeartScan  Common Stock held by the  Purchaser  plus (y) the
number of shares of  HeartScan  Common  Stock into which the Shares  held by the
Purchaser  may be converted  by the sum of (x) the total  number of  outstanding
shares  of  HeartScan  Common  Stock  plus (y) the  total  number  of  shares of
HeartScan Common Stock issuable upon conversion of all outstanding capital stock
convertible  into HeartScan Common Stock or upon the exercise of all options and
warrants to purchase HeartScan Common Stock.

                  (a) Except as set forth below, "New Securities" shall mean any
shares of capital  stock of  HeartScan,  including  Common  Stock and  Preferred
Stock,  whether  now  authorized  or not,  and  rights,  options or  warrants to
purchase said shares of capital  stock,  and  securities of any type  whatsoever
that are,  or may  become,  convertible  into  said  shares  of  capital  stock.
Notwithstanding the foregoing,  "New Securities" does not include (i) securities
offered to the public  generally  pursuant  to a  Qualified  Public  Offering as
defined in Section 5.1(c), (ii) securities issued pursuant to the acquisition of
an unaffiliated  corporation by HeartScan by merger,  purchase of  substantially
all of the assets or other reorganization  whereby HeartScan or its shareholders
own not less than  fifty-one  percent (51%) of the voting power of the surviving
or successor  corporation,  (iii) shares of HeartScan's  Common Stock or options
exercisable  for the purchase of Common Stock issued to employees,  officers and
directors of, and consultants and  franchisees  to,  HeartScan,  pursuant to any
incentive  program  approved by the Board of Directors of HeartScan,  (iv) stock
issued  pursuant to any rights or agreements  outstanding as of the date hereof,
including, without limitation, convertible securities, options and warrants, (v)
stock  issued  in   connection   with  any  stock  split,   stock   dividend  or
recapitalization by HeartScan.

                  (b) In the event  that  HeartScan  proposes  to  undertake  an
issuance  of New  Securities,  it  shall  first  make an  offering  of such  new
securities  to each  Purchaser  by giving the  Purchaser  written  notice of its
intention,  describing the type of New Securities,  and the price and terms upon
which  HeartScan  proposes to issue the same.  The Purchaser  shall have fifteen
(15)  business  days  from the date of  receipt  of any such  notice to agree to
purchase up to its pro rata share of such New  Securities for the price and upon
the terms specified in the notice by giving

                                      -16-

<PAGE>



written  notice to HeartScan and stating  therein the quantity of New Securities
to be purchased.

                  (c) In the event  that the  Purchaser  fails to  exercise  the
right of participation  within said fifteen (15) business day period,  HeartScan
shall promptly, in writing, inform each Purchaser which purchases all the shares
available to it ("Fully-Exercising  Purchaser") of any other Purchaser's failure
to do  likewise.  During the ten-day  period  commencing  after  receipt of such
information,  each Fully-Exercising  Investor shall be entitled to purchase, pro
rata, shares not subscribed for by the other  Purchasers.  If all New Securities
are not elected to be obtained as provided  herein,  HeartScan  shall have sixty
(60) days  thereafter to sell or enter into an agreement  (pursuant to which the
sale of New Securities covered thereby shall be closed, if at all, within thirty
(30)  days  from the date of said  agreement)  to sell  the New  Securities  not
elected to be  purchased  by the  Purchaser  at the price and upon terms no more
favorable to the  purchasers of such  securities  than  specified in HeartScan's
notice.  In the event  HeartScan has not sold the New Securities or entered into
an  agreement to sell the New  Securities  within said sixty (60) day period (or
sold and issued New  Securities in accordance  with the foregoing  within thirty
(30) days from the date of said agreement), HeartScan shall not thereafter issue
or sell any New Securities  without first offering such securities in the manner
provided above.

                  (d) The right of participation  granted under this Section 6.2
shall expire upon the of a Qualified Public Offering.

                  (e) The right of participation hereunder is not assignable, in
whole or in part,  except from the  Purchaser to a  transferee  of the Shares so
long as such  transferee  owns not less than 3,125  shares of Series A Preferred
Stock  or  equivalent   shares  of  Common  Stock  on  an   as-converted   basis
(appropriately adjusted in accordance with the terms hereof).

         6.3  Financial  Information.  Upon  written  request  of  a  Purchaser,
HeartScan will mail the following reports to each Purchaser:

                   (a) As soon as practicable after the end of each fiscal year,
and in any event within 90 days thereafter,  audited consolidated balance sheets
of HeartScan as of the end of such fiscal year, and  consolidated  statements of
income and  shareholders  equity and  consolidated  statements  of cash flows of
HeartScan,  and any  subsidiary  for such  year,  prepared  in  accordance  with
generally  accepted  accounting  principles  and  accompanied  by a report of an
independent  certified  public  accountant  of recognized  standing  selected by
HeartScan; and

                   (b) As soon as practicable after the end of the first, second
and third thirteen week accounting  periods in each fiscal year of HeartScan and
in any  event  within  45 days  thereafter,  a  consolidated  balance  sheet  of
HeartScan  as of the end of each such period,  and  consolidated  statements  of
income and  shareholders  equity and  consolidated  statements  of cash flows of
HeartScan  and any  subsidiary  for such period and for the then current  fiscal
year  to  date,  prepared  in  accordance  with  generally  accepted  accounting
principles  (other than for accompanying  notes),  subject to changes  resulting
from year-end audit adjustments.


                                      -17-

<PAGE>



                   (c) So long as the  Purchaser  is a holder of at least  1,500
Shares such other  information  relating to the financial  condition,  business,
prospects or corporate affairs of HeartScan as a Purchaser from time to time may
reasonably request,  including,  but not limited to annual budgets and financial
plans;  provided,  however,  that  HeartScan  shall not be  obligated to provide
information  which it  reasonably  considers  to be a trade  secret  or  similar
confidential  information unless the Purchaser provides satisfactory  assurances
in writing that it will maintain the  confidentiality of the information and not
use it in any manner detrimental to HeartScan.

                  (d) In addition to the  foregoing,  HeartScan  will permit the
Purchaser,  at  the  Purchaser's  expense,  to  visit  and  inspect  HeartScan's
properties,  to  examine  its  books  of  account  and  records  and to  discuss
HeartScan's  affairs,  finances  and  accounts  with its  officers,  all at such
reasonable times as may be requested by the Purchaser,  provided,  however, that
HeartScan  shall not be obligated  pursuant to this section to provide access to
any  information  which it reasonably  considers to be a trade secret or similar
confidential  information unless the Purchaser provides satisfactory  assurances
in writing that it will maintain the  confidentiality of the information and not
use it any manner detrimental to HeartScan.

                  (e) The Purchaser agrees that any information  obtained by the
Purchaser  pursuant to this Section  which is identified in writing by HeartScan
to be confidential to HeartScan will not be disclosed  without the prior written
consent of HeartScan.

         6.4      Purchasers' Right to Elect Directors.

                  (a) Effective as of the Closing Date, two (2)  representatives
of the Purchasers  shall have been elected  directors of HeartScan.  Imatron and
HeartScan  shall take all action  necessary to ensure that such  representatives
are duly elected in accordance with  HeartScan's  Bylaws.  So long as Purchasers
retain ownership in the aggregate shares of Common Stock (or shares  convertible
into such  shares)  equal to or greater  than 20% of  HeartScan's  Common  Stock
(including  outstanding  Common Stock,  shares of capital stock convertible into
Common Stock and options to purchase  Common Stock)  HeartScan shall include two
(2)  representatives  of the Purchasers among the persons nominated to the Board
of Directors at each annual meeting of HeartScan's  stockholders,  and if and so
long as Purchasers  retain ownership in the aggregate shares of Common Stock (or
shares convertible into such shares) equal to or greater than 10% of HeartScan's
Common  Stock  (including  outstanding  Common  Stock,  shares of capital  stock
convertible  into Common Stock and options to purchase  Common Stock)  HeartScan
shall  include  one (1)  representative  of the  Purchasers  among  the  persons
nominated  to the Board of  Directors  at each  annual  meeting  of  HeartScan's
stockholders.

                  (b) At any time at which  HeartScan's  shareholders  will have
the  right  to or will  vote  for or  consent  in  writing  to the  election  of
directors,  the  Purchasers  and  Imatron  hereby  agree to vote such  shares of
HeartScan's capital stock presently owned or hereafter acquired by them, or over
which  they have  voting  control as are  necessary  to cause and  maintain  the
election to the Board of Directors of the Purchasers' designated representatives
as provided above.


                                      -18-

<PAGE>



                  (c) This  Section 6.4 shall  terminate on the earlier to occur
of the following:  (a) the date on which  HeartScan has  consummated a Qualified
Public Offering, (b) the date on which the Purchasers ownership in the aggregate
shares of Common Stock (or shares convertible into such shares) is less than 10%
of  HeartScan's  Common Stock  (including  outstanding  Common Stock,  shares of
capital  stock  convertible  into Common  Stock and  options to purchase  Common
Stock), and (c) the tenth anniversary of the effective date of this Agreement.

         6.5  Termination.  The  covenants  set forth in this  Section 6, unless
otherwise provided, shall terminate and be of no further force or effect at such
time as HeartScan completes a Qualified Public Offering.

                                    ARTICLE 7

                               NEGATIVE COVENANTS

         HeartScan  covenants  and agrees  that on and after the  Closing  Date,
without the prior written  approval of two-thirds in interest of the Purchasers,
it will not:

         7.1  Dealing  with  Affiliates.  Enter into any  material  transaction,
including,  without  limitation,  any loans or extensions of credit,  release or
guarantee,  management  contract or royalty  agreements,  deferred or contingent
compensation  agreement,  consulting  or other  agreement  with  any  affiliate;
provided  however,  that any  wholly-owned  subsidiary  and any  entity in which
HeartScan  shall have a direct or  indirect  financial  interest  together  with
unaffiliated  third  parties  shall not be an  affiliate  for  purposes  of this
Section 7.1.

         7.2 Conduct of Business. Engage in any business other than the business
engaged in or proposed to be engaged in by  HeartScan or any  subsidiary  on the
date hereof and any  businesses or activities  substantially  similar or related
thereto.

         7.3 Sale of Securities.  Issue and sell any securities other than (i) a
Qualified Public Offering, (ii) up to 470,000 shares of HeartScan's Common Stock
or options  exercisable  for the purchase of Common  Stock issued to  employees,
officers and  directors  of, and  consultants  and  franchisees  to,  HeartScan,
pursuant  to any  incentive  program  approved  by the  Board  of  Directors  of
HeartScan, and (iii) stock issued pursuant to any outstanding security as of the
date hereof or issuable in connection with this offering.

         7.4 Liquidation; Merger, etc. Liquidate or dissolve, merge, consolidate
or sell substantially all of its assets.

         7.5 Dividends;  Distributions;  etc.  Declare or pay any dividends;  or
purchase,  redeem or otherwise acquire for value or make any other  distribution
with respect to any of HeartScan's  capital stock,  other than the repurchase of
shares of capital stock from  terminating or terminated  employees at a price no
greater than fair market value.


                                      -19-

<PAGE>



         7.6  Investments.  Invest,  directly or indirectly,  in any business or
enterprise other than in connection with the operation of its business such as a
joint venture organized to own or operate a coronary  scanning center;  provided
however,  pending  the  use of the  net  proceeds  of  this  offering  in  their
businesses  and subject to the  provisions  of Section 6.1,  above,  Imatron and
HeartScan may invest such net proceeds in short term interest  bearing  deposits
and securities.

                                    ARTICLE 8

                          TRANSFERABILITY OF SECURITIES

         8.1  Transferability.  The Shares and the Imatron Exchange Shares shall
not be sold,  assigned,  transferred  or  pledged  except  upon  the  conditions
specified in this Agreement,  which conditions are intended to ensure compliance
with the  provisions  of the  Securities  Act.  Each  Purchaser  will  cause any
proposed  purchaser,  assignee,  transferee,  or  pledgee  of the  Shares or the
Imatron Exchange Shares to agree to take and hold such securities subject to the
provisions and upon the conditions specified in this Agreement.

         8.2 Restrictive  Legend.  Each certificate  representing (i) the Shares
and (ii) the Imatron Exchange Shares,  and (iii) any other securities  issued in
respect   of  such   securities   upon  any   stock   split,   stock   dividend,
recapitalization, merger, consolidation or similar event shall (unless otherwise
permitted  by the  provisions  of Section  8.3  below) be  stamped or  otherwise
imprinted  with the following  legend (in addition to any legend  required under
applicable state securities laws):

         "THE SHARES  REPRESENTED  BY THIS  CERTIFICATE  HAVE BEEN  ACQUIRED FOR
         INVESTMENT  AND HAVE NOT BEEN  REGISTERED  UNDER THE  SECURITIES ACT OF
         1933. SUCH SHARES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH
         REGISTRATION OR UNLESS THE  CORPORATION  RECEIVES AN OPINION OF COUNSEL
         REASONABLY  ACCEPTABLE  TO IT  STATING  THAT SUCH SALE OR  TRANSFER  IS
         EXEMPT FROM THE  REGISTRATION AND PROSPECTUS  DELIVERY  REQUIREMENTS OF
         SAID ACT."

                  Each  Purchaser  consents  to the  issuer  of such  securities
making a notation on its records and giving  instructions  to any transfer agent
of the  Shares  or of the  Imatron  Exchange  Shares in order to  implement  the
restrictions on transfer established in this Agreement.  As used hereinafter the
term "Restricted  Securities" shall mean the securities of Imatron and HeartScan
required to bear the legend set forth in this section.

         8.3  Notice of  Proposed  Transfers.  The  holder  of each  certificate
representing Restricted Securities by acceptance thereof agrees to comply in all
respects with the  provisions of this Section 8.3.  Prior to any proposed  sale,
assignment,  transfer  or  pledge of any  Restricted  Securities  (other  than a
transfer not  involving a change in  beneficial  ownership),  unless there is in
effect a registration  statement  under the Securities Act covering the proposed
transfer, the

                                      -20-

<PAGE>



holder  thereof shall give written notice to the issuer thereof of such holder's
intention to effect such transfer,  sale, assignment or pledge. Each such notice
shall reasonably describe the manner and circumstances of the proposed transfer,
sale, assignment or pledge, and shall, if reasonably requested by the issuer, be
accompanied,  at such  holder's  expense by either (i) written  opinion of legal
counsel who shall be, and whose legal opinion shall be, reasonably  satisfactory
to Imatron and the issuer of the  relevant  securities  addressed to Imatron and
such  issuer,  to the  effect  that  the  proposed  transfer  of the  Restricted
Securities may be effected  without  registration  under the Securities  Act, or
(ii) a "no action"  letter from the  Securities  and  Exchange  Commission  (the
"Commission")  to the  effect  that  the  transfer  of such  securities  without
registration  will not result in a recommendation by the staff of the Commission
that  action  be taken  with  respect  thereto,  whereupon  the  holder  of such
Restricted  Securities shall be entitled to transfer such Restricted  securities
in accordance  with the terms of the notice  delivered by the holder to Imatron.
Each  certificate  evidencing  the  Restricted  Securities  transferred as above
provided  shall bear,  except if such transfer is made pursuant to Rule 144, the
appropriate  restrictive legend set forth in Section 8.2 above, except that such
certificate shall not bear such restrictive  legend if in the opinion of counsel
for such holder and Imatron  such legend is not  required in order to  establish
compliance  with any provision of the Securities  Act.  HeartScan  shall respond
promptly to any such  request,  but in no event more than ten (10) business days
following receipt of such written notice.

                                    ARTICLE 9

               REGISTRATION RIGHTS RELATING TO IMATRON SECURITIES

         9.1 Certain  Definitions.  As used in this Section, the following terms
shall have the following respective meanings:

                  (a)  "Commission"  shall  mean  the  Securities  and  Exchange
Commission or any other federal agency at the time  administering the Securities
Act.

                  (b)  "First  Exchange  Period  Shares"  shall be the shares of
Imatron Common Stock issuable upon exercise of the First Exchange  Period Rights
provided in Section 5.2 hereof.

                  (c) "Second  Exchange  Period  Shares"  shall be the shares of
Imatron Common Stock issuable upon exercise of the Second Exchange Period Rights
provided in Section 5.3 hereof.

                  (d)  "Holder"  shall mean any  Purchaser  holding  Registrable
Securities  and any person  holding  Registrable  Securities  to whom the rights
under this  Agreement  have been  transferred  in  compliance  with  Section 9.9
hereof.  A Purchaser  shall be deemed to hold any securities to which it has the
right to exchange pursuant to this Agreement.

                  (e) "Registrable Securities" means the Imatron Exchange Shares
issuable  pursuant to the Exchange  Rights;  provided,  however,  that shares of
Imatron Common Stock or

                                      -21-

<PAGE>



other securities shall only be treated as Registrable  Securities if and so long
as (i) such  securities  have not been sold to or  through a broker or dealer or
underwriter in a public distribution or a public securities transaction, or (ii)
all such securities may be sold by the Holder thereof under Rule 144 promulgated
under the Securities Act, or a successor  rule,  within such period as Purchaser
may sell all such securities.

                  (f) The  terms  "register,"  "registered"  and  "registration"
refer  to a  registration  effected  by  preparing  and  filing  a  registration
statement in compliance with the Securities Act, and the declaration or ordering
of the effectiveness of such registration statement.

                  (g) "Registration Expenses" shall mean all expenses, except as
otherwise  stated below,  incurred in complying  with Sections  9.2-9.5  hereof,
including, without limitation, all registration,  qualification and filing fees,
printing  expenses,  escrow fees, fees and  disbursements of counsel for Imatron
and all  reasonable  fees  and  disbursements  of one  counsel  for the  selling
Holders,  blue sky fees and  expenses  and the  expense  of any  special  audits
incident to or required by any such registration (but excluding the compensation
of regular  employees of Imatron which shall be paid in any event by Imatron and
Selling Expenses (as hereinafter defined)).

                  (h) "Selling Expenses" shall mean all underwriting  discounts,
selling  commissions  and stock  transfer  taxes  applicable  to the sale of the
securities  registered by the Holders and,  except as set forth above,  all fees
and disbursements of counsel to Holder.

                  (i) "1934 Act" shall mean the Securities Exchange Act of 1934,
as amended.

         9.2  Registration of First Exchange  Period Shares.  Within one hundred
twenty  (120)  days   following  the  Closing  Date  Imatron  will  effect  such
registration as will permit or facilitate the sale and distribution of the First
Exchange Period Shares.

         9.3      Registration of Second Exchange Period Shares.

                  (a) Within  eighteen  (18) months  following the Closing Date,
Imatron will effect such  registration as will permit or facilitate the sale and
distribution of the Second Exchange Period Shares.  In addition,  after fourteen
(14) months  following the Closing  Date, if any Holder or Holders  request that
Imatron file a registration statement on Form S-3 (or any successor form to Form
S-3) for a public  offering of shares of  Registrable  Securities the reasonably
anticipated  aggregate  price  to the  public  of  which,  net  of  underwriting
discounts and commissions,  would exceed $1,000,000, and Imatron is a registrant
entitled  to use Form S-3 to register  the  Registrable  Securities  for such an
offering,  Imatron  shall  use  its  best  efforts  to  cause  such  Registrable
Securities  to be  registered  for the  offering  on such form and to cause such
Registrable  Securities to be qualified in such  jurisdictions  as the Holder or
Holders may reasonably  request;  provided,  however,  that Imatron shall not be
required to effect more than one  registration  pursuant to this  Section 9.3 in
any six (6) month  period or more than a total of two  registrations  under this
Section 9.3., or if the anticipated offering price net of underwriting

                                      -22-

<PAGE>



discounts  and  commissions  would be less than  $1,000,000.  Upon  receipt of a
notice from a Holder pursuant to this Section 9.3, Imatron will promptly give to
each other Holder written notice thereof;  and include in such registration (and
any related  qualification  under blue sky laws or other  compliance) and in any
underwriting  involved therein,  all the Registrable  Securities  specified in a
written request or requests,  made within twenty (20) days after receipt of such
written notice from Imatron, by any such other Holder.

                  (b)  Notwithstanding  the  foregoing,  Imatron  shall  not  be
obligated  to take any action  pursuant to this  Section  9.3 in any  particular
jurisdiction  in which Imatron would be required to execute a general consent to
service of process in effecting such  registration,  qualification or compliance
unless Imatron is already subject to service in such  jurisdiction and except as
may be required by the Securities Act.

         9.4 Expenses of  Registration.  All Registration  Expenses  incurred in
connection  with a registration  pursuant to Sections 9.2 and 9.3 shall be borne
by Imatron  except that any  registrations  in excess of two pursuant to Section
9.3 shall be borne pro rata by the Holder or Holders requesting the registration
according to the number of Registrable Securities included in such registration.
Unless otherwise stated, all Selling Expenses relating to securities  registered
on behalf of the Holders and all other  registration  expenses shall be borne by
the Holders of such  securities pro rata on the basis of the number of shares so
registered.

         9.5  Registration  Procedures.   In  the  case  of  each  registration,
qualification  or  compliance  effected by Imatron  pursuant to this  Agreement,
Imatron will keep each Holder  advised in writing as to the  initiation  of each
registration,  qualification and compliance and as to the completion thereof. At
its expense Imatron will promptly:

                  (a)  Prepare  and file  with  the  Commission  a  registration
statement with respect to such securities and use its best efforts to cause such
registration  statement to become and remain  effective  until the  distribution
described  in the  Registration  Statement  has been  completed.  In the event a
registration  on Form S-3  shall  be  available  to  Imatron,  the  Registration
Statement shall be filed in such form.

                  (b) Prepare and file with the Commission  such  amendments and
supplements to such registration statement and the prospectus used in connection
with  such  registration  statement  as may be  necessary  to  comply  with  the
provisions  of  the  Securities  Act  with  respect  to the  disposition  of all
securities covered by such registration statement.

                  (c)  Use  its  best   efforts  to  register  and  qualify  the
securities covered by such registration statement under such other securities or
Blue Sky laws of such  jurisdictions  as shall be  reasonably  requested  by the
Holders;  provided that Imatron shall not be required in connection therewith or
as a condition thereto to qualify to do business or to file a general consent to
service  of  process  in any such  states or  jurisdictions,  unless  Imatron is
already  subject to service in such  jurisdiction  and except as may be required
under the Securities Act.


                                      -23-

<PAGE>



                  (d) In the event of any underwritten  public  offering,  enter
into and perform its obligations under an underwriting  agreement,  in usual and
customary  form with the  managing  underwriter  or such  offering.  Each Holder
participating  in such  underwriting  shall  also  enter  into and  perform  its
obligations under such an agreement.

                  (e) Notify each Holder of  Registrable  Securities  covered by
such  registration  statement at any time when a prospectus  relating thereto is
required to be delivered under the Act of the happening of any event as a result
of which the  prospectus  included in such  registration  statement,  as then in
effect,  includes  an untrue  statement  of a material  fact or omits to state a
material fact required to be stated  therein or necessary to make the statements
therein not misleading in the light of the circumstances then existing.

                  (f) Cause all such Registrable  Securities registered pursuant
hereunder to be listed on each securities  exchange on which similar  securities
issued by Imatron are then listed.

                  (g) Provide a transfer agent and registrar for all Registrable
Securities  registered  pursuant  hereunder  and a CUSIP  number  for  all  such
Registrable  Securities  registered,  in each case not later than the  effective
date of such registration.

                  (h) Furnish, at the request of any Holder participating in the
registration of Registrable  Securities  pursuant to this Article 9, on the date
that such  Registrable  Securities are delivered to the underwriters for sale in
connection  with a registration  pursuant to this Article 9, if such  securities
are being sold through  underwriters,  or, if such securities are not being sold
through underwriters,  on the date that the registration  statement with respect
to such securities  becomes effective,  (i) an opinion,  dated such date, of the
counsel representing Imatron for the purposes of such registration,  in form and
substance as is customarily  given to  underwriters  in an  underwritten  public
offering,  addressed to the underwriters,  if any, and to the Holders requesting
registration  of Registrable  Securities and (ii) a letter dated such date, from
the independent  certified public accountants of Imatron,  in form and substance
as  is  customarily  given  by  independent   certified  public  accountants  to
underwriters in an underwritten public offering,  addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities.

                  (i) Furnish to the Holders  participating in such registration
and to the  underwriters  of the securities  being  registered  such  reasonable
number of copies of the registration statement,  preliminary  prospectus,  final
prospectus  and such other  documents  as such  underwriters  or the Holders may
reasonably   request  in  order  to  facilitate  the  public  offering  of  such
securities.

                  (j) Furnish to the Holders  such  information  as such Holders
may  reasonably  request in order for such Holders to perform such due diligence
in connection with any registration as they deem necessary or appropriate.

                  (k) Remove the legend  provided  for under  Section 8.2 hereof
upon such

                                      -24-

<PAGE>



registration;  provided  however,  Imatron may stamp or otherwise imprint on the
certificates  a  legend  providing  that  a  prospectus  must  be  delivered  in
connection with any sale thereof.

                  (l) Deliver to each Holder a letter  confirming the compliance
of each  registration  statement with the requirements of the Securities Act and
the fact that such  registration  statement does not contain an untrue statement
of a material  fact and does not omit to state a material  fact required to make
the statements therein not false or misleading.

                  (m) It shall not be a  condition  of  registration  under this
Article 9 that the Holder exchange the Shares for Imatron Common Stock.

         9.6      Indemnification.

                  (a) Imatron will indemnify each Holder,  each of its officers,
directors  and  partners,  and each person  controlling  such Holder  within the
meaning of Section 15 of the  Securities  Act or the 1934 Act,  with  respect to
which  registration,  qualification or compliance has been effected  pursuant to
this Agreement,  and each underwriter,  if any, and each person who controls any
underwriter  within the meaning of Section 15 of the  Securities Act or the 1934
Act, against all expenses, claims, losses, damages or liabilities (or actions in
respect thereof),  including any of the foregoing  incurred in settlement of any
litigation,  commenced  or  threatened,  arising  out of or based on any  untrue
statement (or alleged  untrue  statement)  of a material  fact  contained in any
registration statement,  prospectus, offering circular or other document, or any
amendment   or   supplement   thereto,   incident  to  any  such   registration,
qualification or compliance,  or based on any omission (or alleged  omission) to
state therein a material fact required to be stated therein or necessary to make
the statements  therein,  in the light of the  circumstances  in which they were
made, not misleading,  or any violation by Imatron of the Securities Act, or the
1934 Act, or any rule or regulation promulgated under the Securities Act, or the
1934 Act, or under any state  securities law or under common law,  applicable to
Imatron in connection with any such  registration,  qualification or compliance,
and Imatron will reimburse each such Holder, each of its officers, directors and
partners,  and each person  controlling  such Holder,  each such underwriter and
each  person  who  controls  any such  underwriter,  for any legal and any other
expenses reasonably incurred,  as such expenses are incurred, in connection with
investigating, preparing or defending any such claim, loss, damage, liability or
action; provided,  however, that Imatron will not be liable (i) for amounts paid
in  settlement  of any such loss,  claim,  damage,  liability  or action if such
settlement is effected  without the consent of Imatron  (which consent shall not
be unreasonably  withheld) and (ii) in any such case to the extent that any such
claim,  loss,  damage,  liability  or  expense  arises out of or is based on any
untrue  statement or omission or alleged untrue  statement or omission,  made in
reliance upon and in conformity with written information furnished to Imatron by
an instrument  duly executed by such Holder,  controlling  person or underwriter
and stated to be specifically for use therein.

                  (b) Each Holder will, if Registrable  Securities  held by such
Holder  are  included  in  the   securities  as  to  which  such   registration,
qualification or compliance is being effected,  indemnify  Imatron,  each of its
directors and officers, each underwriter, if any, of

                                      -25-

<PAGE>



Imatron's securities covered by such a registration  statement,  each person who
controls  Imatron or such  underwriter  within the  meaning of Section 15 of the
Securities  Act, and each other such Holder,  each of its officers and directors
and each person  controlling such Holder within the meaning of Section 15 of the
Securities Act, against all claims,  losses, damages and liabilities (or actions
in respect  thereof) arising out of or based on any untrue statement (or alleged
untrue  statement)  of a  material  fact  contained  in  any  such  registration
statement,  prospectus, offering circular or other document, or any omission (or
alleged omission) to state therein a material fact required to be stated therein
or necessary to make the statements  therein not misleading,  and will reimburse
Imatron,  such Holders,  such  directors,  officers,  persons,  underwriters  or
control  persons  for any legal or any other  expenses  reasonably  incurred  in
connection  with  investigating  or  defending  any such  claim,  loss,  damage,
liability or action,  in each case to the extent,  but only to the extent,  that
such untrue  statement  (or alleged  untrue  statement)  or omission (or alleged
omission) is made in such registration statement,  prospectus, offering circular
or other  document in reliance upon and in conformity  with written  information
furnished to Imatron by an instrument duly executed by such Holder and stated to
be specifically for use therein. Notwithstanding the foregoing, the liability of
each Holder  under this  subsection  (b) (i) shall not apply to amounts  paid in
settlement  of any  such  loss,  claim,  damage,  liability  or  action  if such
settlement is effected  without the consent of the Holder  (which  consent shall
not be unreasonably  withheld),  and (ii) shall be limited in an amount equal to
the  aggregate  net  proceeds of the shares sold by such  Holder,  except to the
extent such  liability  arises out of or is based on willful  misconduct by such
Holder.

                  (c) Each party entitled to indemnification  under this Section
9.6 (the "Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the  Indemnifying  Party to assume  the  defense of any such claim or any
litigation  resulting  therefrom,  provided  that  counsel for the  Indemnifying
Party,  who shall  conduct  the  defense of such claim or  litigation,  shall be
approved by the  Indemnified  Party (whose  approval shall not  unreasonably  be
withheld),  and the  Indemnified  Party may  participate in such defense at such
party's expense,  and provided further that the failure of any Indemnified Party
to give notice as provided  herein shall not relieve the  Indemnifying  Party of
its  obligations  under this Agreement  except to the extent that the failure to
give such notice is materially prejudicial to an Indemnifying Party's ability to
defend such action and provided further,  that the Indemnifying  Party shall not
assume the  defense  for  matters as to which there is a conflict of interest or
separate  and  different  defenses,  but shall pay the fees and  expenses of one
separate counsel retained by the Indemnified Party in the event of such conflict
of  interest.  No  Indemnifying  Party,  in the  defense  of any  such  claim or
litigation, shall, except with the consent of each Indemnified Party, consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
Indemnified  Party of a release  from all  liability in respect to such claim or
litigation.

                  (d) If the indemnification provided for in this Section 9.6 is
held by a court of competent  jurisdiction  to be  unavailable to an indemnified
party with respect to any loss,

                                      -26-

<PAGE>



liability,  claim, damage, or expense referred to therein, then the Indemnifying
Party,  in  lieu  of  indemnifying  such  Indemnified  Party  hereunder,   shall
contribute to the amount paid or payable by such  Indemnified  Party as a result
of such loss,  liability,  claim,  damage,  or expense in such  proportion as is
appropriate to reflect the relative fault of the  Indemnifying  Party on the one
hand and of the Indemnified Party on the other in connection with the statements
or omissions that resulted in such loss, liability, claim, damage, or expense as
well as any other relevant equitable  considerations.  The relative fault of the
Indemnifying Party and of the Indemnified Party shall be determined by reference
to,  among other  things,  whether the untrue or alleged  untrue  statement of a
material  fact or the omission to state a material  fact relates to  information
supplied by the indemnifying  party or by the indemnified party and the parties'
relative intent, knowledge, access to information, and opportunity to correct or
prevent such statement or omission.

                  (f) The  obligations of Imatron and Holders under this Section
9.6 shall survive the completion of any offering of Registrable  Securities in a
registration statement under this Article 9 and otherwise.

         9.7  Information  by  Holder.  The  Holder or  Holders  of  Registrable
Securities   included  in  any  registration   shall  furnish  to  Imatron  such
information regarding such Holder or Holders, the Registrable Securities held by
them and the  distribution  proposed  by such  Holder or Holders as Imatron  may
request in writing and as shall be required in connection with any registration,
qualification or compliance referred to in this Agreement.

         9.8 Rule 144 Reporting. With a view to making available the benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of the Restricted Securities to the public without registration or pursuant
to a registration on Form S-3, Imatron agrees to use its best efforts to:

                   (a) Make  and keep  public  information  available,  as those
terms are understood  and defined in Rule 144 under the  Securities  Act, at all
times after the  effective  date that Imatron  becomes  subject to the reporting
requirements  of the Securities  Act or the Securities  Exchange Act of 1934, as
amended.

                   (b) File with the  Commission  in a timely manner all reports
and  other  documents  required  of  Imatron  under the  Securities  Act and the
Securities  Exchange  Act of 1934,  as amended  (at any time after it has become
subject to such reporting requirements); and

                   (c) So long as a Purchaser owns any Restricted Securities, to
furnish to the Purchaser  forthwith upon request a written  statement by Imatron
as to its compliance  with the reporting  requirements  of said Rule 144 (at any
time after ninety (90) days after the effective  date of the first  registration
statement  filed by Imatron  for an offering  of its  securities  to the general
public),  and of the Securities Act and the Securities  Exchange Act of 1934 (at
any time after it has become subject to such reporting requirements),  a copy of
the most recent  annual or quarterly  report of Imatron,  and such other reports
and documents of Imatron and other

                                      -27-

<PAGE>



information  in the  possession  of or  reasonably  obtainable  by  Imatron as a
Shareholder may reasonably  request in availing itself of any rule or regulation
of the  Commission  allowing a Shareholder to sell any such  securities  without
registration.

         9.9 Transfer of  Registration  Rights.  The rights to cause  Imatron to
register  securities  granted Holders under Sections 9.2 and 9.3 may be assigned
to a transferee  or assignee in  connection  with any transfer or  assignment of
Registrable  Securities  by a  Holder  provided  that:  (i)  such  transfer  may
otherwise be effected in accordance  with  applicable  securities  laws and (ii)
such assignee or transferee becomes a party to this Agreement and assumes all of
the obligations of the transferring Holder under Article 9.

         9.10 Additional  Shares. In the event that Imatron shall fail to comply
with Section 9.5(b) or fail to cause the registration  with respect to the First
Exchange Period Shares to become  effective within one hundred twenty (120) days
of the Closing  Date as provided  in Section 9.2 or in the event  Imatron  shall
fail to cause the  registration  of the Second  Exchange Period Shares to become
effective within eighteen (18) months of the Closing Date as provided in Section
9.3, Imatron shall pay to the Purchasers for each month or portion thereof until
such  registrations  become effective an amount equal to one percent (1%) of the
greater  of (i) the  purchase  price  paid  for  such  shares  pursuant  to this
Agreement,  or (ii) the value of such shares  measured  by the  average  closing
price of a share of Imatron  Common Stock on the five  trading days  immediately
preceding  the dates one  hundred  twenty  (120) days and  eighteen  (18) months
following the Closing  Date, as the case may be. Such payments  shall be paid by
the delivery to the  Purchasers  of shares of Imatron  Common valued in the same
manner  as in (ii)  above.  Provided  that  Imatron  shall  continue  to use its
reasonable  best  efforts  to cause such  registration  to become  effective  as
promptly  as  practicable,  the  delivery  of  such  shares  shall  be  in  full
satisfaction  of any  liability  on the part of Imatron  for failing to register
such shares as provided herein;  provided  further  however,  that such delivery
shall not excuse  Imatron  from the  obligation  to register  all of such shares
which  obligation  shall  continue.  Any shares of Imatron  Common  Stock issued
pursuant to this Section 9.10 shall be subject to the same  registration  rights
provided in this Section 9. In connection with the issuance of such shares, each
Purchaser  shall,  if requested  by Imatron,  confirm in writing with respect to
such shares the  representations  and warranties  set forth in Sections  4.1-4.6
above.


                                   ARTICLE 10

              REGISTRATION RIGHTS RELATING TO HEARTSCAN SECURITIES

         10.1 Certain Definitions.  As used in this Section, the following terms
shall have the following respective meanings:

                  (a)  "Commission"  shall  mean  the  Securities  and  Exchange
Commission or any other federal agency at the time  administering the Securities
Act.


                                      -28-

<PAGE>



                  (b)  "Holder"  shall  mean  any  Purchaser  holding  HeartScan
Registrable Securities and any person holding Registrable Securities to whom the
rights under this  Agreement have been  transferred  in compliance  with Section
10.10 hereof. A Purchaser shall be deemed to hold any HeartScan  securities into
which it has a right to convert.

                  (c)  "Registrable  Securities"  means (i) the HeartScan Common
Stock to be issued upon the  conversion  of the  Shares,  and (ii) any common or
preferred  stock of  HeartScan  issued or issuable in respect of the Shares sold
and  transferred  pursuant  to this  Agreement  or other  securities  issued  or
issuable  upon any stock split,  stock  dividend,  recapitalization,  or similar
event,  or any capital  stock  otherwise  issued or issuable with respect to the
Shares sold and transferred pursuant to this Agreement;  provided, however, that
shares of HeartScan  Common Stock or other  securities  shall only be treated as
Registrable  Securities if and so long as (A) such securities have not been sold
to or through a broker or dealer or  underwriter in a public  distribution  or a
public  securities  transaction,  or (B) all such  securities may be sold by the
Holder  thereof  under  Rule 144  promulgated  under the  Securities  Act,  or a
successor rule, within such period as Purchaser may sell all such securities.

                  (d) The  terms  "register,"  "registered"  and  "registration"
refer  to a  registration  effected  by  preparing  and  filing  a  registration
statement in compliance with the Securities Act, and the declaration or ordering
of the effectiveness of such registration statement.

                  (e) "Registration Expenses" shall mean all expenses, except as
otherwise  stated  below,  incurred by  HeartScan  in  complying  with  Sections
10.2-10.6 hereof, including, without limitation, all registration, qualification
and filing fees,  printing  expenses,  escrow fees,  fees and  disbursements  of
counsel for HeartScan and all reasonable fees and  disbursements  of one counsel
for the  selling  Holders,  blue sky fees and  expenses  and the  expense of any
special audits incident to or required by any such  registration  (but excluding
the  compensation  of regular  employees of HeartScan which shall be paid in any
event by HeartScan and Selling Expenses (as hereinafter defined)).

                  (f) "Securities Act" shall mean the Securities Act of 1933, as
amended,  or any similar  federal  statute and the rules and  regulations of the
commission thereunder, all as the same shall be in effect at the time.

                  (g) "Selling Expenses" shall mean all underwriting  discounts,
selling  commissions  and stock  transfer  taxes  applicable  to the  securities
registered by the Holders and, except as set forth above.

                  (i) "1934 Act" shall mean the Securities Exchange Act of 1934,
as amended.



                                      -29-

<PAGE>



         10.2     Registration by HeartScan.

                  (a)  Notice  of  Registration.  If at any time or from time to
time HeartScan shall determine to register any of its equity securities,  either
for its own account or the account of a security  holder or holders,  other than
(i) a  registration  relating  solely  to  employee  benefit  plans  or  (ii)  a
registration  relating  solely to a Rule 145  transaction,  HeartScan  will: (A)
promptly give to each Holder  written  notice  thereof;  and (B) include in such
registration  (and  any  related  qualification  under  blue  sky  laws or other
compliance)  and in any  underwriting  involved  therein,  all  the  Registrable
Securities  specified in a written request or requests,  made within twenty (20)
days after receipt of such written notice from HeartScan, by any Holder.

                  (b) Underwriting. If the registration of which HeartScan gives
notice is for a registered public offering involving an underwriting,  HeartScan
shall so advise the Holders as a part of the written  notice  given  pursuant to
Section 10.2. In such event the right of any Holder to registration  pursuant to
this Section 10.2 shall be conditioned upon such Holder's  participation in such
underwriting and the inclusion of Registrable  Securities in the underwriting to
the extent provided herein. All Holders proposing to distribute their securities
through such  underwriting  shall (together with HeartScan and the other holders
distributing  their  securities   through  such  underwriting)   enter  into  an
underwriting  agreement in customary form with the managing underwriter selected
for such underwriting by HeartScan.  Notwithstanding any other provision of this
Section 10.2, if the managing  underwriter  determines  that  marketing  factors
require a limitation  of the number of shares to be  underwritten,  the managing
underwriter  may require from each Holder,  as a condition  for  including  such
Holder's  Registrable  Securities in such  registration,  the agreement from the
Holder not to sell any or part of the Registrable Securities for a period of one
hundred  twenty (120) days  following  the  effective  date of the  registration
statement.  If any  Holder  or  holder  disapproves  of the  terms  of any  such
underwriting,  he or she may elect to withdraw  therefrom  by written  notice to
HeartScan and the managing underwriter.

                  (c) Right to Terminate Registration.  HeartScan shall have the
right to  terminate  or withdraw  any  registration  initiated  by it under this
Section 10.2 prior to the effectiveness of such registration  whether or not any
Holder has elected to include securities in such registration.

         10.3     Registration on Form S-3.

                  (a) If any Holder or Holders  request  that  HeartScan  file a
registration  statement  on Form S-3 (or any  successor  form to Form S-3) for a
public offering of shares of Registrable  Securities the reasonably  anticipated
aggregate  price to the  public  of which,  net of  underwriting  discounts  and
commissions,  would exceed $1,000,000, and HeartScan is a registrant entitled to
use  Form S-3 to  register  the  Registrable  Securities  for such an  offering,
HeartScan shall use its best efforts to cause such Registrable  Securities to be
registered  for  the  offering  on  such  form  and to  cause  such  Registrable
Securities  to be qualified in such  jurisdictions  as the Holder or Holders may
reasonably request; provided, however, that

                                      -30-

<PAGE>



HeartScan shall not be required to effect more than one registration pursuant to
this  Section  6.6 in any six (6)  month  period  or  more  than a total  of two
registrations under this Section 6.6., or if the anticipated  offering price net
of underwriting  discounts and commissions  would be less than  $1,000,000.  The
notice  provisions  of  Section  6.6 shall be  applicable  to each  registration
initiated under this Section 10.3.

                  (b)  Notwithstanding  the  foregoing,  HeartScan  shall not be
obligated  to  take  any  action  pursuant  to  this  Section  10.3:  (i) in any
particular  jurisdiction  in which  HeartScan  would be  required  to  execute a
general   consent  to  service  of  process  in  effecting  such   registration,
qualification  or compliance  unless  HeartScan is already subject to service in
such  jurisdiction  and except as may be required by the Securities Act; (ii) if
HeartScan,  within ten (10) days of the receipt of the request of the initiating
Holders,  gives  notice of its bona fide  intention  to effect  the  filing of a
registration statement with the commission within ninety (90) days of receipt of
such request (other than with respect to a registration  statement relating to a
Rule 145 transaction,  an offering solely to employees or any other registration
which is not appropriate for the registration of Registrable Securities);  (iii)
during the period  starting  with the date sixty (60) days prior to  HeartScan's
estimated  date of filing of, and ending on the date six (6) months  immediately
following,  the  effective  date of any  registration  statement  pertaining  to
securities of HeartScan  (other than a registration  of securities in a Rule 145
transaction  or  with  respect  to an  employee  benefit  plan),  provided  that
HeartScan is actively  employing in good faith all  reasonable  efforts to cause
such  registration  statement to become  effective;  or (iv) if HeartScan  shall
furnish  to such  Holder or Holders a  certificate  signed by the  President  of
HeartScan  stating that in the good faith  judgment of the Board of Directors it
would be seriously detrimental to HeartScan or its shareholders for registration
statements to be filed at such time, then HeartScan's obligation to use its best
efforts to file a registration  statement  shall be deferred for a period not to
exceed one  hundred  twenty  (120) days from the  receipt of the request to file
such  registration by such Holder;  provided  however,  that HeartScan shall not
utilize this right more than once in any twelve month  period.  The  limitations
set forth in this Section 10.3(b) shall not apply to registrations under Section
10.2

         10.4 Limitations on Subsequent  Registration Rights. From and after the
date of this Agreement, HeartScan shall not, without the consent of Holders of a
majority of the Registrable  Securities,  enter into any agreement  granting any
holder or prospective holder of any securities of HeartScan  registration rights
with respect to such securities unless such new registration  rights,  including
standoff obligations, are subordinate to the registration rights granted Holders
hereunder.

         10.5 Expenses of Registration.  All Registration  Expenses  incurred in
connection with a registration pursuant to Sections 10.2 and 10.3 shall be borne
by HeartScan except that any  registrations in excess of two pursuant to Section
10.3  shall  be  borne  pro  rata  by  the  Holder  or  Holders  requesting  the
registration  according to the number of Registrable Securities included in such
registration.   Unless  otherwise  stated,  all  Selling  Expenses  relating  to
securities  registered  on behalf  of the  Holders  and all  other  Registration
Expenses shall be borne by the Holders of such  securities pro rata on the basis
of the number of shares so registered.

                                      -31-

<PAGE>




         10.6  Registration  Procedures.  In  the  case  of  each  registration,
qualification  or compliance  effected by HeartScan  pursuant to this Agreement,
HeartScan  will keep each Holder advised in writing as to the initiation of each
registration,  qualification and compliance and as to the completion thereof. At
its expense HeartScan will:

                  (a)  Prepare  and file  with  the  Commission  a  registration
statement with respect to such securities and use its best efforts to cause such
registration  statement to become and remain  effective for at least one hundred
eighty  (180)  days or until  the  distribution  described  in the  Registration
Statement has been completed;  provided,  however,  that (i) such 180-day period
shall be extended  for a period of time equal to the period the Holder  refrains
from selling any securities  included in such  registration at the request of an
underwriter of Common Stock (or other securities) of HeartScan;  and (ii) in the
case of any  registration  of  Registrable  Securities  on Form  S-3  which  are
intended to be offered on a continuous  or delayed  basis,  such 180-day  period
shall be extended,  if necessary,  to keep the registration  statement effective
until all such Registrable  Securities are sold,  provided that Rule 415, or any
successor  rule under the Act,  permits an offering on a  continuous  or delayed
basis,  and provided  further that  applicable  rules under the  Securities  Act
governing the obligation to file a post-effective  amendment  permit, in lieu of
filing a post-effective  amendment which (A) includes any prospectus required by
Section  10(a)(3)  of the  Securities  Act  or  (B)  reflects  facts  or  events
representing a material or fundamental  change in the  information  set forth in
the  registration  statement,  the  incorporation  by reference  of  information
required to be included in (A) and (B) above to be contained in periodic reports
filed  pursuant  to  Section  13 or 15(d)  of the  1934 Act in the  registration
statement.

                  (b) Prepare and file with the Commission  such  amendments and
supplements to such registration statement and the prospectus used in connection
with  such  registration  statement  as may be  necessary  to  comply  with  the
provisions  of  the  Securities  Act  with  respect  to the  disposition  of all
securities covered by such registration statement.

                  (c)  Use  its  best   efforts  to  register  and  qualify  the
securities covered by such registration  statement such other securities or Blue
sky laws of such jurisdictions as shall be reasonably  requested by the Holders;
provided that  HeartScan  shall not be required in connection  therewith or as a
condition  thereto  to qualify to do  business  or to file a general  consent to
service of process in any such  states or  jurisdictions,  unless  HeartScan  is
already  subject to service in such  jurisdiction  and except as may be required
under the Securities Act.

                  (d) In the event of any underwritten  public  offering,  enter
into and perform its obligations under an underwriting  agreement,  in usual and
customary  form with the  managing  underwriter  or such  offering.  Each Holder
participating  in such  underwriting  shall  also  enter  into and  perform  its
obligations under such an agreement.

                  (e) Notify each Holder of  Registrable  Securities  covered by
such  registration  statement at any time when a prospectus  relating thereto is
required to be delivered under the

                                      -32-

<PAGE>



Act of the happening of any event as a result of which the  prospectus  included
in such registration  statement, as then in effect, includes an untrue statement
of a  material  fact or omits to state a  material  fact  required  to be stated
therein or necessary to make the statements  therein not misleading in the light
of the circumstances then existing.

                  (f) Cause all such Registrable  Securities registered pursuant
hereunder to be listed on each securities  exchange on which similar  securities
issued by HeartScan are then listed.

                  (g) Provide a transfer agent and registrar for all Registrable
Securities  registered  pursuant  hereunder  and a CUSIP  number  for  all  such
Registrable Securities registered, in each case not late than the effective date
of such registration.

                  (h)  Furnish,   at  the  request  of  any  Holder   requesting
registration of Registrable  Securities pursuant to this Article 10, on the date
that such  Registrable  Securities are delivered to the underwriters for sale in
connection  with a registration  pursuant to this Article 10, if such securities
are being sold through  underwriters,  or, if such securities are not being sold
through underwriters,  on the date that the registration  statement with respect
to such securities  becomes effective,  (i) an opinion,  dated such date, of the
counsel  representing  HeartScan for the purposes of such registration,  in form
and substance as is customarily given to underwriters in an underwritten  public
offering,  addressed to the underwriters,  if any, and to the Holders requesting
registration  of Registrable  Securities and (ii) a letter dated such date, from
the independent certified public accountants of HeartScan, in form and substance
as  is  customarily  given  by  independent   certified  public  accountants  to
underwriters in an underwritten public offering,  addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities.

                  (i) Furnish to the Holders  participating in such registration
and to the  underwriters  of the securities  being  registered  such  reasonable
number of copies of the registration statement,  preliminary  prospectus,  final
prospectus and such other documents as such underwriters may reasonably  request
in order to facilitate the public offering of such securities.

                  (j) Furnish to the Holders  such  information  as such Holders
may  reasonably  request in order for such Holders to perform such due diligence
in connection with any registration as they deem necessary or appropriate.

                  (k) Remove the legend  provided  for under  Section 8.2 hereof
upon such registration; provided however, Imatron may stamp or otherwise imprint
on the  certificates a legend  providing that a prospectus  must be delivered in
connection with any sale thereof.

                  (l) Deliver to each Holder a letter  confirming the compliance
of each  registration  statement with the requirements of the Securities Act and
the fact that such  registration  statement does not contain an untrue statement
of a material  fact and does not omit to state a material  fact required to make
the statements therein not false or misleading.

                                      -33-

<PAGE>




                  (m) It shall not be a  condition  of  registration  under this
Article that the Holder convert the Shares into HeartScan Common Stock.

         10.7     Indemnification.

                  (a) HeartScan will indemnify each Holder, each of its officers
and directors and partners,  and each person  controlling such Holder within the
meaning of Section 15 of the  Securities  Act or the 1934 Act,  with  respect to
which  registration,  qualification or compliance has been effected  pursuant to
this Agreement,  and each underwriter,  if any, and each person who controls any
underwriter  within the meaning of Section 15 of the  Securities Act or the 1934
Act, against all expenses, claims, losses, damages or liabilities (or actions in
respect thereof),  including any of the foregoing  incurred in settlement of any
litigation,  commenced  or  threatened,  arising  out of or based on any  untrue
statement (or alleged  untrue  statement)  of a material  fact  contained in any
registration statement,  prospectus, offering circular or other document, or any
amendment   or   supplement   thereto,   incident  to  any  such   registration,
qualification or compliance,  or based on any omission (or alleged  omission) to
state therein a material fact required to be stated therein or necessary to make
the statements  therein,  in the light of the  circumstances  in which they were
made, not  misleading,  or any violation by HeartScan of the Securities  Act, or
the 1934 Act, or any rule or regulation promulgated under the Securities Act, or
the 1934 Act,  applicable to HeartScan in connection with any such registration,
qualification or compliance, and HeartScan will reimburse each such Holder, each
of its officers and  directors and partners,  and each person  controlling  such
Holder, each such underwriter and each person who controls any such underwriter,
for any legal and any other expenses reasonably  incurred,  as such expenses are
incurred,  in  connection  with  investigating,  preparing or defending any such
claim, loss, damage, liability or action; provided, however, that HeartScan will
not be liable  (i) for  amounts  paid in  settlement  of any such  loss,  claim,
damage,  liability or action if such settlement is effected  without the consent
of HeartScan (which consent shall not be unreasonably  withheld) and (ii) in any
such case to the extent that any such claim, loss, damage,  liability or expense
arises out of or is based on any untrue  statement or omission or alleged untrue
statement  or omission,  made in reliance  upon and in  conformity  with written
information  furnished  to  HeartScan  by an  instrument  duly  executed by such
Holder,  controlling person or underwriter and stated to be specifically for use
therein.

                  (b) Each Holder will, if Registrable  Securities  held by such
Holder  are  included  in  the   securities  as  to  which  such   registration,
qualification or compliance is being effected,  indemnify HeartScan, each of its
directors and officers,  each  underwriter,  if any, of  HeartScan's  securities
covered by such a registration statement,  each person who controls HeartScan or
such  underwriter  within the meaning of Section 15 of the  Securities  Act, and
each other such  Holder,  each of its  officers  and  directors  and each person
controlling  such Holder within the meaning of Section 15 of the Securities Act,
against  all claims,  losses,  damages  and  liabilities  (or actions in respect
thereof)  arising out of or based on any untrue  statement  (or  alleged  untrue
statement)  of a material  fact  contained in any such  registration  statement,
prospectus,  offering  circular or other  document,  or any omission (or alleged
omission)  to state  therein a material  fact  required to be stated  therein or
necessary to make the statements therein

                                      -34-

<PAGE>



not  misleading,  and will reimburse  HeartScan,  such Holders,  such directors,
officers,  persons,  underwriters  or control persons for any legal or any other
expenses  reasonably  incurred in connection with investigating or defending any
such claim, loss,  damage,  liability or action, in each case to the extent, but
only to the extent,  that such untrue statement (or alleged untrue statement) or
omission  (or  alleged  omission)  is  made  in  such  registration   statement,
prospectus,  offering  circular  or  other  document  in  reliance  upon  and in
conformity with written information furnished to HeartScan by an instrument duly
executed  by  such  Holder  and  stated  to be  specifically  for  use  therein.
Notwithstanding  the  foregoing,   the  liability  of  each  Holder  under  this
subsection  (b) (i) shall not apply to amounts  paid in  settlement  of any such
loss, claim, damage,  liability or action if such settlement is effected without
the consent of the Holder (which  consent shall not be  unreasonably  withheld),
and (ii) shall be limited in an amount  equal to the  aggregate  initial  public
offering price of the shares sold by such Holder,  unless such liability  arises
out of or is based on willful conduct by such Holder.

                  (c) Each party entitled to indemnification  under this Section
10.7 (the  "Indemnified  Party")  shall  give  notice to the party  required  to
provide   indemnification   (the  "Indemnifying   Party")  promptly  after  such
Indemnified Party has actual knowledge of any claim as to which indemnity may be
sought,  and shall  permit the  Indemnifying  Party to assume the defense of any
such claim or any litigation resulting therefrom,  provided that counsel for the
Indemnifying  Party,  who shall conduct the defense of such claim or litigation,
shall  be  approved  by  the   Indemnified   Party  (whose  approval  shall  not
unreasonably  be withheld),  and the  Indemnified  Party may participate in such
defense at such party's  expense,  and provided  further that the failure of any
Indemnified  Party to give  notice as  provided  herein  shall not  relieve  the
Indemnifying  Party of its obligations under this Agreement except to the extent
the failure to give such notice is  materially  prejudicial  to an  Indemnifying
Party's  ability  to  defend  such  action  and  provided   further,   that  the
Indemnifying Party shall not assume the defense for matters as to which there is
a conflict of interest or separate  and  different  defenses,  but shall pay the
fees and expenses of one separate counsel  retained by the Indemnified  Party in
the event of such conflict of interest. No Indemnifying Party, in the defense of
any such claim or litigation, shall, except with the consent of each Indemnified
Party,  consent to entry of any judgment or enter into any settlement which does
not  include as an  unconditional  term  thereof  the giving by the  claimant or
plaintiff to such  Indemnified  Party of a release from all liability in respect
to such claim or litigation.

                  (d) If the  indemnification  provided for in this Section 10.7
is held by a court of competent jurisdiction to be unavailable to an indemnified
party with respect to any loss, liability, claim, damage, or expense referred to
therein,  then the Indemnifying  Party, in lieu of indemnifying such Indemnified
Party  hereunder,  shall  contribute  to the  amount  paid  or  payable  by such
Indemnified Party as a result of such loss, liability, claim, damage, or expense
in such  proportion  as is  appropriate  to reflect  the  relative  fault of the
Indemnifying  Party on the one hand and of the Indemnified Party on the other in
connection  with  the  statements  or  omissions  that  resulted  in such  loss,
liability,  claim,  damage,  or expense as well as any other relevant  equitable
considerations.  The  relative  fault  of  the  Indemnifying  Party  and  of the
Indemnified  Party shall be  determined  by reference  to,  among other  things,
whether the untrue or alleged

                                      -35-

<PAGE>



untrue  statement of a material  fact or the  omission to state a material  fact
relates to information  supplied by the indemnifying party or by the indemnified
party and the parties' relative intent,  knowledge,  access to information,  and
opportunity to correct or prevent such statement or omission.

                  (e)  Notwithstanding  the  foregoing,  to the extent  that the
provisions on  indemnification  and  contribution  contained in the underwriting
agreement  entered into in connection with the underwritten  public offering are
in conflict with the foregoing  provisions,  the provisions in the  underwriting
agreement shall control.

                  (f) The  obligations  of  HeartScan  and  Holders  under  this
Section  10.7 shall  survive  the  completion  of any  offering  of  Registrable
Securities in a registration statement under this Section 10.7 and otherwise.

         10.8  Information  by Holder.  The  Holder or  Holders  of  Registrable
Securities  included  in  any  registration  shall  furnish  to  HeartScan  such
information regarding such Holder or Holders, the Registrable Securities held by
them and the  distribution  proposed by such Holder or Holders as HeartScan  may
request in writing and as shall be required in connection with any registration,
qualification or compliance referred to in this Agreement.

         10.9 Rule 144 Reporting.  With a view to making  available the benefits
of certain rules and regulations of the Commission  which may at any time permit
the sale of the  Restricted  Securities to the public  without  registration  or
pursuant  to a  registration  on Form S-3,  after  such time as a public  market
exists  for the  Common  Stock of  HeartScan,  HeartScan  agrees to use its best
efforts to:

                   (a) Make  and keep  public  information  available,  as those
terms are understood  and defined in Rule 144 under the  Securities  Act, at all
times after the effective date that HeartScan  becomes  subject to the reporting
requirements  of the Securities  Act or the Securities  Exchange Act of 1934, as
amended.

                   (b) File with the  Commission  in a timely manner all reports
and other  documents  required of  HeartScan  under the  Securities  Act and the
Securities  Exchange  Act of 1934,  as amended  (at any time after it has become
subject to such reporting requirements); and

                   (c) So long as a Purchaser owns any Restricted Securities, to
furnish to the Purchaser forthwith upon request a written statement by HeartScan
as to its compliance  with the reporting  requirements  of said Rule 144 (at any
time after ninety (90) days after the effective  date of the first  registration
statement  filed by HeartScan  for an offering of its  securities to the general
public),  and of the Securities Act and the Securities  Exchange Act of 1934 (at
any time after it has become subject to such reporting requirements),  a copy of
the most recent annual or quarterly report of HeartScan,  and such other reports
and  documents  of  HeartScan  and other  information  in the  possession  of or
reasonably  obtainable by HeartScan as a Shareholder  may reasonably  request in
availing itself of any rule or regulation of the Commission allowing a

                                      -36-

<PAGE>



Shareholder to sell any such securities without registration.

         10.10 Transfer of Registration Rights. The rights to cause HeartScan to
register securities granted Holders under Sections 10.2 and 10.3 may be assigned
to a transferee  or assignee  reasonably  acceptable  to HeartScan in connection
with any transfer or assignment of Registrable  Securities by a Holder  provided
that: (i) such transfer may otherwise be effected in accordance  with applicable
securities  laws and (ii) such  assignee or  transferee  becomes a party to this
Agreement and assumes all of the  obligations of the  transferring  Holder under
this Section 10.10.

         10.11  Standoff  Agreement.  Each Holder agrees upon the initial public
offering of  HeartScan's  securities  in  connection  with any  registration  of
HeartScan's   securities  in  an  initial  public  offering  other  than  (i)  a
registration  relating  solely to employee  benefit plans or (ii) a registration
relating  solely to a Rule 145  transaction,  upon  request of  HeartScan or the
underwriters managing any underwritten offering of HeartScan's  securities,  not
to sell, make any short sale of, loan,  grant any option for the purchase of, or
otherwise  dispose of any Registrable  Securities  (other than those included in
the  registration)  without  the prior  written  consent  of  HeartScan  or such
underwriters,  as the case may be,  for such  period of time (not to exceed  one
hundred twenty (120) days) from the effective date of such  registration  as may
be requested by the underwriters.

                                   ARTICLE 11

                     CONDITIONS TO CLOSING OF THE PURCHASERS

         The  Purchasers'  obligation  to purchase the Shares at the Closing are
subject to the fulfillment of the following  conditions (which conditions may be
waived by the Purchasers):

         11.1  Representations and Warranties  Correct.  The representations and
warranties  made by Imatron in Section 3 hereof  shall be true and correct as of
the Closing Date.

         11.2 Covenants.  All covenants,  agreements and conditions contained in
this  Agreement to be performed by Imatron on or prior to the Closing Date shall
have been performed or complied with by Imatron.

         11.3 Qualifications. Imatron shall have obtained all necessary Blue Sky
law  permits  and  qualifications,   or  have  the  availability  of  exemptions
therefrom,  required  authorizations,  approvals,  or  permits,  if any,  of any
governmental  authority or regulatory  body of the United States or of any state
in connection with the offer and sale of the Shares.

         11.4  Legal  Matters.  All  material  matters of a legal  nature  which
pertain to this Agreement and the transactions  contemplated  hereby, shall have
been reasonably approved by counsel to the Purchasers.


                                      -37-

<PAGE>



         11.5 Proceedings and Documents.  All corporate and other proceedings in
connection with the  transactions  contemplated at the Closing and all documents
incident  thereto  shall be  reasonably  satisfactory  in form and  substance to
Purchasers'  counsel,  and such counsel shall have received all such counterpart
original and certified or other copies of such  documents as they may reasonably
request.

         11.6 Opinion of Imatron's and HeartScan's Counsel. Each purchaser shall
have received from Severson & Werson,  A Professional  Corporation,  counsel for
Imatron and HeartScan, an opinion, dated as of the Closing, in the form attached
hereto as Exhibit E.

         11.7 Secretaries'  Certificates.  The respective Secretaries of Imatron
and  HeartScan  shall  deliver  to counsel  for the  Purchasers  at the  Closing
certificates  certifying,  among other things,  the approval of the transactions
contemplated  hereby by Imatron's and  HeartScan's  Board of Directors,  and the
continued full force and effect of Imatron's and HeartScan's respective Articles
of Incorporation and Bylaws.

         11.8 Good Standing.  Imatron and HeartScan shall deliver to counsel for
the  Purchasers at the Closing  certificates  of good  standing  executed by the
Secretary  of  State  in each  jurisdiction  where  Imatron  and  HeartScan  are
incorporated.

         11.9  Equipment  Supply  Agreement.  Imatron and  HeartScan  shall have
entered into an Equipment Supply Agreement  substantially in the form previously
provided to counsel to the Purchasers.

                                   ARTICLE 12

                        CONDITIONS TO CLOSING OF IMATRON

         Imatron's obligation to transfer and sell the Shares at the Closing is,
at the option of Imatron,  subject to the  fulfillment  on or before the Closing
Date of the following conditions:

         12.1  Representations and Warranties.  The representations  made by the
Purchasers in Section 4 hereof shall be true and correct when made, and shall be
true and correct on the Closing Date.

         12.2 Further Representations and Warranties. In the event any Purchaser
shall  have been  organized  for the  purpose  of  purchasing  the  Shares,  the
beneficial owners of such Purchaser shall have provided to Imatron and HeartScan
such  information,  representations  and warranties as Imatron and HeartScan may
reasonably require.

         12.3 Qualifications. Imatron shall have obtained all necessary Blue Sky
law  permits  and  qualifications,   or  have  the  availability  of  exemptions
therefrom,  required  authorizations,  approvals,  or  permits,  if any,  of any
governmental  authority or regulatory  body of the United States or of any state
in connection with the offer and sale of the Shares.

                                      -38-

<PAGE>




         12.4  Legal  Matters.  All  material  matters of a legal  nature  which
pertain to this Agreement, and the transactions  contemplated hereby, shall have
been reasonably approved by counsel to Imatron.


                                   ARTICLE 13
                                  MISCELLANEOUS

         13.1 Governing Law. This Agreement shall be governed in all respects by
the internal laws of the State of Delaware.

         13.2  Survival.   The   representations,   warranties,   covenants  and
agreements made herein shall survive any investigation  made by the Purchaser or
Imatron and the closing of the transactions contemplated hereby.

         13.3 Successors and Assigns.  Except as otherwise  provided herein, the
provisions  hereof  shall  inure to the  benefit  of, and be binding  upon,  the
successors,  assigns, heirs, executors and administrators of the parties hereto,
provided,  however,  that the rights of a Purchaser to purchase the Shares shall
not be assignable without the consent of Imatron.

         13.4 Entire  Agreement;  Amendment.  This Agreement or any term hereof,
may be amended,  waived,  discharged or terminated  with the written  consent of
Imatron,  HeartScan and Purchasers holding at least a majority of the Shares (or
HeartScan  Common Stock issuable upon conversion of the Shares).  This Agreement
and the other documents  delivered pursuant hereto at the Closing constitute the
full and entire  understanding  and agreement between the parties with regard to
the subjects  hereof and  thereof,  and no party shall be liable or bound to any
other party in any manner by any warranties, representations or covenants except
as  specifically  set forth  herein or  therein.  Except as  expressly  provided
herein,  neither  this  Agreement  nor any term hereof may be  amended,  waived,
discharged or terminated other than by a written  instrument signed by the party
against whom enforcement of any such amendment, waiver, discharge or termination
is sought.

         13.5  Notices,  etc. All notices and other  communications  required or
permitted  hereunder  shall be in writing and shall be mailed by  registered  or
certified mail, postage prepaid,  or otherwise delivered by hand or by messenger
or courier, addressed as follows:

         To Imatron or
                  HeartScan:  Imatron Inc.
                              389 Oyster Point Blvd.
                              South San Francisco, California 94080
                              Attention: President

         With a copy to:      Severson & Werson

                                      -39-

<PAGE>



                              One Embarcadero Center, 25th Floor
                              San Francisco, California 94111
                              Attention: Roger S. Mertz, Esq.

         To any Purchaser:    At its address specified in
                                    Exhibit A hereto

         With a copy to:      Werbel McMillin & Carnelutti
                              711 Fifth Avenue, 5th Floor
                              New York, New York 10022
                              Attention: Stephen M. Davis, Esq.

         Each such notice or other  communication shall for all purposes of this
Agreement be treated as effective on receipt.

         13.6 Delays or Omissions. Except as expressly provided herein, no delay
or omissionto  exercise any right, power or remedy accruing to any holder of any
Shares, upon any breach or default of Imatron under this Agreement, shall impair
any such right, power or remedy of such holder nor shall it be construed to be a
waiver of any such breach or default,  or an acquiescence  therein,  or of or in
any similar breach or default thereafter occurring;  nor shall any waiver of any
single  breach or  default  be deemed a waiver  of any other  breach or  default
theretofore or thereafter occurring.  Any waiver, permit, consent or approval of
any kind or character  on the part of any holder of any breach or default  under
this  Agreement,  or any waiver on the part of any holder of any  provisions  or
conditions of this agreement,  must be in writing and shall be effective only to
the extent  specifically set forth in such writing.  All remedies,  either under
this  Agreement  or by  law  or  otherwise  afforded  to any  holder,  shall  be
cumulative and not alternative.

         13.7  California  Corporate  Securities Law. THE SALE OF THE SECURITIES
WHICH  ARE THE  SUBJECT  OF THIS  AGREEMENT  HAS NOT  BEEN  QUALIFIED  WITH  THE
COMMISSIONER OF CORPORATIONS OF THE STATE OF CALIFORNIA AND THE ISSUANCE OF SUCH
SECURITIES OR THE PAYMENT OR RECEIPT OF ANY PART OF THE  CONSIDERATION  THEREFOR
PRIOR TO SUCH  QUALIFICATION IS UNLAWFUL UNLESS THE SALE OF SECURITIES IS EXEMPT
FROM THE  QUALIFICATION  BY  SECTION  25100,  25102  OR 25105 OF THE  CALIFORNIA
CORPORATIONS  CODE.  THE RIGHTS OF ALL PARTIES TO THIS  AGREEMENT  ARE EXPRESSLY
CONDITIONED  UPON  SUCH  QUALIFICATION  BEING  OBTAINED,  UNLESS  THE SALE IS SO
EXEMPT.

         13.8 Expenses. Imatron and the Purchasers shall bear their own expenses
incurred  on its behalf  with  respect to this  Agreement  and the  transactions
contemplated hereby, except that Imatron shall pay the reasonable legal expenses
incurred by the Purchasers not to exceed an aggregate total of $10,000.

         13.9 Remedies. Imatron and HeartScan stipulate that the remedies at law
of the

                                      -40-

<PAGE>



Purchasers in the event of any default or threatened  default by either  Imatron
or HeartScan in the  performance of or compliance  with any of the terms of this
Agreement  are  not  and  will  not be  adequate  and  that  such  terms  may be
specifically  enforced by a decree for the specific performance of any agreement
contained  herein or by an  injunction  against a violation  of any of the terms
hereof.

         13.10  Attorneys  Fees. In any action or proceeding  brought to enforce
any  provision  of this  Agreement,  the  successful  party shall be entitled to
recover  the  reasonable  attorneys'  fees in  addition  to any other  available
remedy.

         13.11  Counterparts.  This  Agreement  may be executed in any number of
counterparts,  each of which may be  executed  by less than all of the  parties,
each of which shall be enforceable  against the parties actually  executing such
counterparts, and all of which together shall constitute one instrument.

         13.12  Severability.  In the event that any provision of this Agreement
becomes or is  declared  by a court of  competent  jurisdiction  to be  illegal,
unenforceable  or void,  this Agreement  shall continue in full force and effect
without said provision; provided that no such severability shall be effective if
it materially changes the economic benefit of this Agreement to any party.

         13.13  Titles and  Subtitles.  The titles  and  subtitles  used in this
Agreement are used for convenience  only and are not considered in construing or
interpreting this Agreement.

         The foregoing  agreement is hereby  executed as of the date first above
written.

                              IMATRON

                                  IMATRON INC.


                                  By /s/ S. Lewis Meyer
                                    -------------------------
                                     S. Lewis Meyer,
                                     President

                              HEARTSCAN

                                  HEARTSCAN IMAGING, INC.


                                  By /s/ Dale E. Grant
                                    -------------------------
                                    Dale E. Grant,
                                    President

                              PURCHASERS

                                  SC FUNDAMENTAL VALUE FUND, L.P.

                                  By /s/
                                    ---------------------------
                                    Its________________________

                                      -41-

<PAGE>





                               HAVE A HEART, LLC


                               By /s/
                                 ---------------------------
                                 Its Managing Member


                               SC FUNDAMENTAL VALUE, BVI, LTD.


                               By /s/
                                 ---------------------------
                                 Its



                  (Signature Page to Stock Purchase Agreement)


                               ELLIOTT ASSOCIATES, L.P.


                               By /s/
                                 ---------------------------
                                 Its


                               CRAMER, ROSENTHAL, McGLYNN, INC.


                               By /s/
                                 ---------------------------
                                 Its


                               RAVICH REVOCABLE TRUST OF 1989
                               JESS M. RAVICH, TRUSTEE


                               By /s/ Jess M. Ravich, Trustee
                                 ----------------------------
                                 Jess M. Ravich, Trustee






                                      -42-

<PAGE>



                               GRACE BROTHERS, LTD.


                               By /s/ Bradford T. Whitmore
                                 ----------------------------
                                 BRADFORD T. WHITMORE
                                 Its General Partner

                  (Signature Page to Stock Purchase Agreement)

                                THE GALILEO FUND, L.P.
                                By DDJ Galileo, LLC, its General Partner


                                By  /s/ Judy K. Mencher
                                 ----------------------------
                                  Judy K. Mencher
                                  Its:  Member


                                WESTGATE INTERNATIONAL, L.P.
                                By: Martley International, Inc.,
                                   its Attorney-in-Fact


                                By /s/
                                 ----------------------------
                                  Its


                                LAKESHORE INTERNATIONAL LIMITED
                                By:  Global Capital Management, Inc.,
                                       Investment Manager


                                By /s/ John D. Brandenborg
                                 ----------------------------
                                  John D. Brandenborg
                                  Its: Vice President

                                MERCED PARTNERS LIMITED PARTNERSHIP
                                By: Global Capital Management, Inc.,
                                       Investment Manager


                                By /s/ John D. Brandenborg
                                 ----------------------------
                                   John D. Brandenborg
                                   Its:  Vice President

                                      -43-

<PAGE>




                                 MODERN WOODMEN OF AMERICA

                                 By /s/
                                 ----------------------------
                                   Its


                  (Signature Page to Stock Purchase Agreement)


                                /s/ Joseph B. Galichia, M.D.
                                ----------------------------
                                JOSEPH B. GALICHIA, M.D.


                                LAGUNITAS PARTNERS, L.P.


                                By /s/ Jon Gruber
                                 ----------------------------
                                  Jon Gruber, General Partner

                                 THE COPERNICUS FUND, L.P.


                                By /s/
                                 ----------------------------
                                 Its___________________________________

                                CREDIT SUISSE (GUERNSEY) LIMITED


                                By /s/
                                 ----------------------------
                                  Its


                                BANQUE PRIVEE EDMOND DE
                                ROTHSCHILD S.A.


                                By /s/ Charles Cay
                                 ----------------------------
                                  Charles Cay
                                  Its:  First Vice President

                                By /s/ Lisiane Spicher
                                 ----------------------------
                                  Lisiane Spicher
                                  Its:  Authorized Officer

                                      -44-

<PAGE>





                                REINFRANK LIVING TRUST UA 6/13/96


                                By /s/ R. Rudolph Reinfrank
                                 ----------------------------
                                  R. Rudolph Reinfrank, Trustee

                  (Signature Page to Stock Purchase Agreement)

                                STEPHEN P. RADER AND ANNE W. RADER,
and                             their successors, as trustees of the 
                                Rader Living Trust
                                dated 09/09/94

                                /s/ Stephen P. Rader
                                ----------------------------
                                By Stephen P. Rader, Trustee



                                /s/ Gary Post
                                ----------------------------
                                GARY POST



                                A.B. LAFFER, V.A. CANTO & ASSOCIATES


                                By /s/
                                 ----------------------------
                                  Its___________________________________


                                /s/ Kathleen Sullivan
                                ----------------------------
                                KATHLEEN SULLIVAN


                                /s/ Mark Siegel
                                ----------------------------
                                MARK SIEGEL









                                      -45-

<PAGE>



                              Schedule of Exhibits


Exhibit A - Schedule of Purchasers

Exhibit B - Schedule of Exceptions

Exhibit C - Summary of Capitalization of Imatron and HeartScan

Exhibit D - Certificates of Designation of Preferences of Series A Preferred 
                  Stock and Series B Preferred Stock

Exhibit E - Form of Opinion of Counsel to Imatron and HeartScan

                                      -46-

<PAGE>


<TABLE>

                                                              EXHIBIT A


                                                       Schedule of Purchasers
<CAPTION>


            Name of and Registered                           Purchase
             Address of Purchaser                             Price                                 No. of Shares
<S>                                                         <C>                                       <C>
SC Fundamental Value Fund,                                  $3,480,000                                21,750
L.P.
712 Fifth Avenue
New York, NY 10019
Attn:  Neil Koffler
Tel: (212) 957-3500
Fax  (212) 957-3434

Have A Heart, LLC.                                          $2,000,000                                12,500
c/o The Yucaipa Companies
10000 Santa Monica Blvd., 5th
Floor
Los Angeles, CA 90067
Attn:  Mark A. Resnik
Tel: (310) 789-7200
Fax: (310) 789-7201

SC Fundamental Value BVI, Ltd.                              $1,520,000                                 9,500
c/o Citco Fund Services
Corporate Center, West Bay Road
Box 31106 SMB
Grand Cayman, Cayman Islands
Tel: (212) 957-3500
Fax  (212) 957-3434

Elliott Associates, L.P.                                    $1,332,800                                 8,330
712 Fifth Avenue, 36th Floor
New York, New York 10019
Attn: Mark D. Brodsky
Tel:  (212) 974-2151
Fax:  (212) 974-2092




                                       -i-

<PAGE>





Ravich Revocable Trust of 1989                              $1,000,000                                 6,250
Jess M. Ravich, Trustee
c/o Libra Investments, Inc.
11766 Wilshire Blvd., Suite 870
Los Angeles, CA 90025
Attn:  Jess Ravich
Tel:  (310) 312-5600
Fax:  (310) 312-5665

Grace Brothers, Ltd.                                          $900,000                                 5,625
1560 Sherman Avenue, Suite 9000
Evanston, IL 60201
Attn:  Brad Whitmore
Tel:  (847) 733-1230
Fax:  (847) 733-0339

CRM Partners, L.P.                                            $776,000                                 4,850
707 Westchester Ave.
White Plains, New York 10604
Attn:  Gene Trainor
Tel:  (914) 681-4475
Fax:  (914) 682-3618

The Galileo Fund, L.P.                                        $680,000                                 4,250
141 Linden St., Suite 4
Wellesley, MA 02181
Attn:  Jay Burnham
Tel:  (617) 283-8500
Fax:  (617) 283-8555


                                      -ii-

<PAGE>





Westgate International, L.P.                                  $667,200                                 4,170
c/o Midland Bank Trust
Corporation
  (Cayman) Limited
P.O. Box 1109
Mary Street
Grand Cayman, Cayman Islands

Notices to:
c/o Stonington Management
Corporation
712 Fifth Avenue. 36th Floor
New York, New York 10019
Attn: Mark D. Brodsky
Tel: (212) 974-2151
Fax: (212) 974-2092


Lakeshore International Ltd.                                  $520,000                                 3,250
601 Lakeshore Parkway, Suite 200
Minnetonka, MN 55305
Attn:  Dale Wilenbring
Tel:  (612) 476-7241
Fax:  (612) 476-7201

Merced Partners Limited                                       $480,000                                 3,000
  Partnership
By:  Global Capital Management,
Inc.
  General Partner
601 Carlson Parkway, Suite 200
Minnetonka, MN 55305
Attn:  Dale Wilenbring
Tel:  (612) 476-7241
Fax:  (612) 476-7201


                                      -iii-

<PAGE>





Modern Woodmen Of America                                     $400,000                                 2,500
1701 First Avenue
Rock Island, IL 61201
Attn:  Mike Dau
Tel:  (309) 793-5566
Fax:  (309) 786-1701


Joseph P. Galichia, M.D.                                      $400,000                                 2,500
551 North Hillside, #410
Wichita, Kansas 67214
Tel:  (316) 688-9112
Fax:  (316) 688-9181

Lagunitas Partners L.P.                                       $400,000                                 2,500
50 Osgood - Penthouse
San Francisco, CA 94133
Tel:  (415) 981-2101
Fax:  (415) 956-7858


CRM Retirement Partners, L.P.                                 $384,000                                 2,400
707 Westchester Ave.
White Plains, New York 10604
Attn:  Gene Trainor
Tel:  (914) 681-4475
Fax:  (914) 682-3618

The Copernicus Fund, L.P.                                     $320,000                                 2,000
141 Linden Street, Suite 4
Wellesley, MA 02181
Tel:  (617) 283-8500
Fax:  (617) 283-8555

CRM Madison Partners, L.P.                                    $192,000                                 1,200
707 Westchester Ave.
White Plains, New York 10604
Attn:  Gene Trainor
Tel:  (914) 681-4475
Fax:  (914) 682-3618


                                      -iv-

<PAGE>





Credit Suisse (Guernsey) Limited                              $128,000                                   800
Helvetia Court
P.O. Box 368
St. Peter Port, Guernsey
Channel Islands BY1 3YJ
Attn:  Nikki Baudains
Tel:  (41)(22) 818-9111
Fax:  (41)(22) 818-9127


Banque Privee Edmond de                                        $96,000                                   600
Rothschild,
   S.A. Geneva
18 rue de Hesse
CH 1204 Geneve
Switzerland
Attn:  Charles Gay, First Vice
President
Tel:  (4122) 818.91.11
Fax:  (4122) 818.91.21

Reinfrank Living Trust UA                                      $72,000                                   450
6/13/95
R. Rudolph Reinfrank, Trustee
6725 Zumirez Drive
Malibu, CA 90265
Tel:  (310) 551-2286
Fax:  (310) 561-0591

Stephen P. Rader and Anne W.                                   $72,000                                   450
Rader, and their successors, as
trustees of the Rader Living Trust
dated 09/09/94
18850 Rosita St.
Tarzana, CA 91356
Tel:  (310) 556-7614
Fax:  (310) 556-3568


                                       -v-

<PAGE>





Cramer, Rosenthal, McGlynn,                                    $48,000                                   300
Inc.
707 Westchester Ave.
White Plains, New York 10604
Attn:  Gene Trainor
Tel:  (914) 681-4475
Fax:  (914) 682-3618

Gary Post                                                      $48,000                                   300
Ambient Capital Group, Inc.
10990 Wilshire Blvd., Suite 1800
Los Angeles, CA 90024
Attn:  Gary Post
Tel:  (310) 445-2323
Fax:  (310) 445-2330

A.B. Laffer, V.A. Canto                                        $48,000                                   300
   & Associates
5405 Morehouse Drive, Suite 340
San Diego, CA 92121
Attn:  Howard Appel
Tel:  (619) 458-0811
Fax:  (619) 458-9856


Kathleen Sullivan                                              $19,200                                   120
c/o David Cooper, CPA
11-11 Tahquitz Canyon Way,
Suite 113
Palm Springs, CA 92262
Tel:  (619) 320-2002
Fax:  (619)


Mark S. Siegel                                                 $16,800                                   105
c/o Remy Investors & Consultants
1801 Century Park East, Suite 111
Los Angeles, CA 90067
Tel:  (310) 843-0050
Fax:  (310) 843-0010

</TABLE>


                                      -vi-

<PAGE>




                                    EXHIBIT B

                                   Exceptions


Section 3.4.  Subsidiaries

         HeartScan Imaging, Inc.
         Imatron Japan Inc.
         InVision Technologies, Inc.

<TABLE>

Section 3.7.  Financial Statements

         Imatron has  guaranteed  the  following  leases on behalf of  HeartScan
Imaging, Inc.:
<CAPTION>


                                                                                                  Initial
                                                                                                  Monthly
Lessor                              Site                           Term                           Payment
<S>                                 <C>                           <C>                           <C>
Finova                              Seattle, WA                   06/95-07/00                   $45,240

CIT                                 Houston, TX                   01/96-02/01                   $36,316

NDS                                 Washington, DC                07/96-06/01                   $27,805

NDS                                 Pittsburgh, PA                07/96-06/01                   $27,805

Pacific Consolidated                Seattle, WA                   08/94-07/98                   $ 6,449

TMH Medical Offices                 Houston, TX                   06/95-05/00                   $ 5,855

Laing Properties                    Washington, DC                01/96-12/06                   $ 5,351
</TABLE>


Section 3.13. Litigation

         Siemens Corporation, Imatron's distributor in the United States, Europe
and certain other countries, has asserted a claim against Imatron as a result of
the lapse of certain  foreign  registrations  of one of the patents  assigned to
Siemens by Imatron in connection  with the March 31, 1995 agreement  between the
companies. The technology involved in the patent is not presently used in any of
Imatron's  products and Imatron  believes that  resolution of the claim will not
have a material  adverse  impact upon it.  Imatron and Siemens  have  reached an
agreement in  principle  to  substitute a new patent in place of the patent with
respect to which certain foreign registrations have lapsed.

Section 3.15.  Registration Rights

         Imatron has entered into numerous  registration  rights agreements with
purchasers of

                                       -i-

<PAGE>



its                                           (Exhibit B - Continued)


securities  in the 1992 unit  offering,  the 1995  private  placement,  the 1996
private placement and other minor purchasers of its securities.  Pursuant to the
1996 private  placement,  Imatron has agreed to register 4,000,000 shares of its
Common  Stock  within  60 days  of May 24,  1996.  If such  registration  is not
effective as of such date, the purchasers of such shares have a right to rescind
the transaction.


         HeartScan  has  agreed  to  provided  registration  rights  to  Imatron
covering the shares of common stock  issuable  upon  conversion  of its Series B
Preferred Stock.

Section 3.17.  Material Contracts

         See Exception to Section 3.13.


                                      -ii-

<PAGE>



                                    EXHIBIT C

<TABLE>

                       Summary of Pro-Forma Capitalization

<CAPTION>

Imatron Inc.
                                                                                                             Common
                                                                                                             Shares

<S>                                                                                                      <C>
         Common Stock outstanding                                                                        76,268,990
         Common Stock issuable upon exercise of outstanding warrants                                      3,722,560
         Common Stock reserved for issuance under option and other plans                                  6,648,209
         Common Stock reserved for issuance under S-3 registration                                        1,500,000
         Common Stock reserved for issuance under the Agreement                                          10,666,667
                                                                                                         ----------
                                                                                                         98,806,426
                                                                                                         ==========

HeartScan Imaging, Inc.

                                                                                                             Common
                                                                                                             Shares

         Common Stock Outstanding                                                                            21,094
         Common Stock issuable upon conversion of Series A Preferred                                      1,000,000
         Common Stock issuable upon conversion of Series B Preferred                                      1,000,000
         Warrants to be issued in connection with Agreement                                                  30,000
         Common Stock reserved for issuance under stock option plans                                        448,906
                                                                                                          ---------
                                                                                                          2,500,000
                                                                                                          =========
</TABLE>

                                       -i-

<PAGE>



                                    EXHIBIT D



      Certificates of Designation of Series A Preferred Stock and Series B
                   Preferred Stock of HeartScan Imaging, Inc.


                            CERTIFICATE OF AMENDMENT

                                       OF

                           CERTIFICATE OF DESIGNATION

                                       OF

                             HEARTSCAN IMAGING, INC.

                             Pursuant to Section 242
                          of the Corporation Law of the
                                State of Delaware


         HeartScan Imaging,  Inc. (the "Corporation"),  a Corporation  organized
and existing under the General  Corporation  Law of the State of Delaware,  does
hereby certify as follows:

         The  Board  of  Directors  of the  Corporation,  on June 10,  1996,  by
unanimous written consent pursuant to Section 141 of the General Corporation Law
of the State of  Delaware,  adopted  resolutions  pursuant to Section 242 of the
General  Corporation  Law  of  Delaware,  setting  forth  an  amendment  to  the
Certificate of  Designation  of the Series A Preferred  Stock and declaring said
amendment to be advisable. The stockholder of the Corporation duly approved said
proposed  amendment by written consent in accordance with Section 228 and 242 of
the General  Corporation  Law of the state of Delaware.  The resolution  setting
forth the amendment is as follows:

         RESOLVED, that the Certificate of Designation of the Series A Preferred
Stock of this

                                       -i-

<PAGE>



Corporation  be  amended  by  restating  in  its  entirety  the  Certificate  of
Designation Relating to the Series A Preferred Stock of HeartScan Imaging,  Inc.
to read as follows:

         RESOLVED,  that  pursuant  to the  authority  expressly  granted by the
Certificate of Incorporation,  as amended,  of the Corporation,  there is hereby
created a series of  Preferred  Stock,  $.001 par value,  consisting  of 200,000
shares,  the issuance of which is hereby  authorized,  which shall be designated
"Series  A  Preferred  Stock"  and  which  shall  have  the  following   rights,
preferences, voting powers, privileges and restrictions in addition to those set
forth in the Certificate of Incorporation, as amended, of the Corporation:

         Section 1.  Dividends.  The holders of  outstanding  shares of Series A
Preferred  shall be entitled to receive in any fiscal year, out of any assets at
the time legally  available  therefor,  dividends in cash in such amounts and at
such times as the Board of  Directors  deems  advisable.  No  dividend  or other
distribution  shall be declared or paid on any share of Common Stock (other than
a stock dividend payable in Common Stock) or on any share of any series or class
of Preferred  Stock unless an equal dividend per share is declared on the Series
A  Preferred  (on an  as-converted  basis)  and paid at the same  time as on the
Common Stock.

         Section 2.  Liquidation Preference.

                  (a) In the event of any liquidation, dissolution or winding up
of the Corporation, either voluntary or involuntary, the holders of the Series A
Preferred  shall be  entitled  on a pro rata basis to  receive,  prior to and in
preference  to any  distribution  of any of the assets or  surplus  funds of the
Corporation  to the holders of the Common Stock and any other series or class of
Preferred  Stock,  including  the Series B Preferred  Stock,  by reason of their
ownership  thereof,  the amount of One Hundred Sixty Dollars ($160.00) per share
for each share of Series A Preferred  then held by them,  and, in  addition,  an
amount  equal to all  accrued  but  unpaid  dividends  on the shares of Series A
Preferred  then held by them.  If upon  occurrence  of such event the assets and
funds thus distributed  among the holders of the Series A Preferred Shares shall
be insufficient  to permit the payment to such holders of the full  preferential
amount,  then the entire assets and funds of the Corporation  legally  available
for distribution shall be distributed  ratably among the holders of the Series A
Preferred  Shares in proportion to the  preferential  amount each such holder is
otherwise entitled to receive. After payment has been made to the holders of the
Series A Preferred Shares of the full amounts to which they shall be entitled as
aforesaid,  the holders of the Common Stock, the Series A Preferred Shares,  and
on any  other  series  or class of  Preferred  Stock  shall  share  ratably  all
remaining  assets of the  Corporation  in  proportion to the number of shares of
Common Stock

                                      -ii-

<PAGE>



then held by them (on an as-converted basis).

                  (b) For purposes of this Section 2, a merger or  consolidation
of this  Corporation with or into any other  Corporation or Corporations  (other
than a  wholly  owned  subsidiary  Corporation),  or  the  merger  of any  other
Corporation(s) into this Corporation, or the sale of all or substantially all of
the  assets  of this  Corporation,  or any  corporate  reorganization,  in which
consolidation, merger, sale of assets or reorganization the stockholders of this
Corporation receive  distributions in cash, property,  rights or securities as a
result of such consolidation, merger, sale of assets or reorganization, shall be
treated as a liquidation, dissolution or winding up of this Corporation and such
distributions shall be made in accordance with Section 2(a) above.

         Section 3. Conversion. The holders of the Series A Preferred shall have
conversion rights as follows: (the "Conversion Rights"):

                  (a) Optional and Automatic Conversion.  Each share of Series A
Preferred  shall be  convertible  at the option of the holder  thereof,  without
payment of  additional  consideration  at any time after the date of issuance of
such share at the office of the Corporation or any transfer agent for the Series
A Preferred,  into such number of fully paid and nonassessable  shares of Common
Stock,  as is  determined  by dividing  Ten Dollars  ($10.00) by the  Conversion
Price,  determined as hereinafter provided, in effect at the time of conversion.
The price at which shares of Common Stock shall be deliverable  upon  conversion
(the  "Conversion  Price")  shall  initially be One Dollar  ($1.00) per share of
Common Stock (the "Initial  Conversion  Price").  Such Initial  Conversion Price
shall be subject to adjustment as hereinafter  provided.  Each share of Series A
Preferred shall be  automatically  converted,  without the payment of additional
consideration,  into such shares of Common Stock upon the closing of a Qualified
Public  Offering.  For  purposes of this  subsection  (b), a  "Qualified  Public
Offering" means an initial public  offering of the  HeartScan's  common stock to
the general public with a post-offering  pre-proceeds fully-diluted valuation of
the equity  existing  as of June 26,  1996 (such  equity  consisting  of 100,000
issued  and  outstanding  shares  of  Series A  Preferred,  100,000  issued  and
outstanding  shares  of  Series  B  Preferred,   21,094  shares  of  issued  and
outstanding  reserved Common Stock and 448,906  reserved shares of Common Stock)
of no less than $56,000,000 for an initial public offering during the first year
following  June 26,  1996 and no less than  $78,000,000  for an  initial  public
offering  during the second year  following  June 26, 1996 for an initial public
offering  resulting  in  net  proceeds  to the  Corporation  of  not  less  than
$15,000,000,   which  initial  public   offering  is  effected   pursuant  to  a
registration statement filed with, and declared effective by, the Securities and
Exchange Commission under the Securities Act.

                  (b)  Mechanics of Conversion of Series A Preferred Stock.  No

                                      -iii-

<PAGE>



fractional  shares of Common Stock shall be issued upon  conversion  of Series A
Preferred.  In lieu of any fractional shares to which the holder would otherwise
be entitled, the Corporation shall pay cash equal to such fraction multiplied by
the then  effective  Conversion  Price.  Before any holder of Series A Preferred
shall be entitled to convert  the same into full shares of Common  Stock,  (s)he
shall surrender the certificate(s) therefor, duly endorsed, at the office of the
Corporation  or of any transfer  agent for the Series A Preferred  respectively,
and shall give  written  notice to the  Corporation  at such  office  that (s)he
elects to  convert  the same.  The  Corporation  shall,  as soon as  practicable
thereafter,  issue  and  deliver  at such  office  to such  holder  of  Series A
Preferred,  a  certificate(s),  registered  in such  names as  specified  by the
holder,  for the  number  of  shares of  Common  Stock to which  (s)he  shall be
entitled  as  aforesaid  and a check  payable to the holder in the amount of any
cash amounts  payable as the result of a conversion  into  fractional  shares of
Common Stock,  and any accrued and unpaid  dividends on the  converted  Series A
Preferred Stock respectively.  Such conversion shall be deemed to have been made
immediately  prior to the close of business on the date of such surrender of the
shares of Series A Preferred  to be  converted,  and the  person(s)  entitled to
receive  shares of Common Stock issuable upon such  conversion  shall be treated
for all purposes as the record  holder(s) of such shares of Common Stock on such
date.  If  the  conversion  is in  connection  with  an  underwritten  offer  of
securities  registered  pursuant to the Securities Act of 1933 or with any other
transaction,  the conversion may, at the option of any holder tendering Series A
Preferred for conversion,  be conditioned  upon the closing with the underwriter
of the sale of securities  pursuant to such offering or the closing of the other
transaction,  in which event the holder  entitled  to receive  the Common  Stock
issuable upon such  conversion of the Series A Preferred  shall not be deemed to
have converted such Series A Preferred until immediately prior to the closing of
such sale of securities or of such other transaction.

                  (c)  Adjustments to Conversion Price.

                           (i) In the  event  the  outstanding  shares of Common
Stock shall be combined or consolidated,  by reclassification or otherwise, into
a lesser  number  of  shares of Common  Stock,  the  Conversion  Price in effect
immediately prior to such combination or consolidation shall,  concurrently with
the  effectiveness  of such  combination or  consolidation,  be  proportionately
increased.

                           (ii) In the event the  Corporation  shall  declare or
pay any dividend on the Common Stock payable in Common Stock or in the event the
outstanding shares of Common Stock shall be subdivided,  by  reclassification or
otherwise  than by payment of a dividend in Common Stock,  into a greater number
of shares of Common Stock, the Conversion Price in effect  immediately  prior to
such dividend or subdivision shall be proportionately decreased:


                                      -iv-

<PAGE>



                                             (A)  in  the   case  of  any   such
dividend,  immediately  after the close of  business  on the record date for the
determination  of holders of any class of  securities  entitled to receive  such
dividend, or

                                             (B)  in  the   case  of  any   such
subdivision,  at the close of business on the date immediately prior to the date
upon which such corporate action becomes effective.

         If such record date shall have been fixed and such  dividend  shall not
have been fully paid on the date fixed therefor,  the adjustment previously made
in the  Conversion  Price which  became  effective  on such record date shall be
cancelled as of the close of business on such record date,  and  thereafter  the
Conversion  Price  shall be  adjusted  as of the time of actual  payment of such
dividend.

                  (d) No Impairment.  The Corporation  will not, by amendment of
its  Certificate of  Incorporation  or through any  reorganization,  transfer of
assets, consolidation,  merger, dissolution,  issue or sale of securities or any
other voluntary action,  avoid or seek to avoid the observance or performance of
any of the terms to be observed or performed  hereunder by the  Corporation  but
will at all times in good faith assist in the carrying out of all the provisions
of this  Section 3 and in the taking of all such action as may be  necessary  or
appropriate  in order to protect  the  Conversion  Rights of the  holders of the
Series A Preferred against impairment.

         The Corporation  shall from time to time in accordance with the laws of
the State of Delaware  increase the authorized  amount of its Common Stock if at
any time the number of Common Stock shares remaining  unissued and available for
issuance shall not be sufficient to permit  conversion of the Series A Preferred
as appropriate.

                  (e) Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment  of the Conversion  Price pursuant to this Section 3,
the  Corporation  at its expense  shall  promptly  compute  such  adjustment  or
readjustment  in accordance  with the terms hereof and furnish to each holder of
Series A Preferred as appropriate a certificate setting forth such adjustment or
readjustment  and  showing in detail the facts  upon  which such  adjustment  or
readjustment is based.  The Corporation  shall,  upon the written request at any
time of any holder of Series A  Preferred,  furnish or cause to be  furnished to
such  holder  a  like  certificate   setting  forth  (i)  such  adjustments  and
readjustments,  (ii) the Conversion  Price at the time in effect,  and (iii) the
number of shares of Common Stock and the amount, if any, of other property which
at the time would be received upon the conversion of Series A Preferred.

                  (f)  Reservation of Common Stock. The Corporation shall at all

                                       -v-

<PAGE>



times have reserved from its authorized  and unissued  Common Stock a sufficient
number of shares of Common Stock to satisfy the conversion  rights of the shares
of Series A Preferred Stock.

                  (g) Notices of Record Date. In the event that this Corporation
shall propose at any time:

                           (i) to declare any dividend or distribution  upon its
Common Stock, whether in cash, property,  stock or other securities,  whether or
not a  regular  cash  dividend  and  whether  or not out of  earnings  or earned
surplus;

                           (ii)  to  offer  for  subscription  pro  rata  to the
holders  of any class or series of its stock any  additional  shares of stock of
any class or series or other rights;

                           (iii)   to    effect    any    reclassification    or
recapitalization  of its  Common  Stock  outstanding  involving  a change in the
Common Stock; or

                           (iv) to merge or  consolidate  with or into any other
Corporation,  or sell, lease or convey all or substantially  all its property or
business,  or to liquidate,  dissolve or wind up; then, in connection  with each
such event, this Corporation shall send to the holders of the Series A Preferred
shares:

                                    (1) at least 30 days' prior  written  notice
of the date on which a record shall be taken for such dividend,  distribution or
subscription  rights  (and  specifying  the date on which the  holders of Common
Stock shall be entitled thereto) or for determining rights to vote in respect of
the matters referred to in (iii) and (iv) above; and

                                    (2) in the case of the  matters  referred to
in (iii) and (iv) above, at least 30 days' prior written notice of the date when
the same shall take place (and  specifying,  if  practicable,  or estimating the
date on which the holders of Common  Stock  shares shall be entitled to exchange
their Common Stock shares for securities or other property  deliverable upon the
occurrence of such event).

         Each such written  notice  shall be given by first class mail,  postage
prepaid,  addressed to the holders of Series A Preferred at the address for each
such holder as shown on the books of this Corporation.

         Section 4. Voting  Rights.  Except as otherwise  required by law,  each
share of Series A Preferred Stock issued and outstanding shall have the right to
vote with the  holders of Common  Stock on all  matters,  each share of Series A
Preferred Stock having that number of votes equal to the number of Common

                                      -vi-

<PAGE>



Stock shares into which the Series A Preferred is  convertible  as adjusted from
time to time.

         Section 5.  Residual  Rights.  All rights  accruing to the  outstanding
shares of this  Corporation  not expressly  provided for to the contrary  herein
shall be vested in the Common Stock.

         Section 6. No reissuance  of Series A Preferred.  No shares of Series A
Preferred  acquired  by this  Corporation  by  reason of  redemption,  purchase,
conversion or otherwise, shall be reissued.

         Section 7. Covenants.  In addition to any other rights provided by law,
so long as any Series A Preferred shall be outstanding,  this Corporation  shall
not,  without first  obtaining the  affirmative  vote or written  consent of the
holders  of not less  than  two-thirds  of such  outstanding  shares of Series A
Preferred:

                  (a) Amend or repeal any provision of, or add any provision to,
this  Corporation's  Certificate of Incorporation or Bylaws if such action would
alter or  change  the  preferences,  rights,  privileges  or  powers  of, or the
restrictions  provided for the benefit of, any Series A Preferred or increase or
decrease the number of Series A Preferred authorized hereby;

                  (b)  reclassify  any  Common  Stock  into  shares  having  any
preference or priority as to dividends or assets superior to or on a parity with
any such preference or priority of the Series A Preferred;

                  (c) apply any of its  assets  to the  redemption,  retirement,
purchase  or  acquisition  directly  or  indirectly.   through  subsidiaries  or
otherwise, of any Common Stock, except from officers,  directors or employees of
or  consultants  to this  Corporation or its  subsidiaries  upon  termination of
employment,  directorship or consulting  pursuant to the terms of stock purchase
agreements  or  restricted  stock  purchase  agreements  entered  into with such
officers, directors, employees or consultants.

                                      -vii-

<PAGE>




         IN WITNESS  WHEREOF,  the Corporation has caused its seal to be affixed
hereto and this  Certificate  of  Amendment  to be signed by its  President  and
attested by its Secretary this 10th day of June, 1996.


                                          HEARTSCAN IMAGING, INC.

                                          BY_______________________
                                               President



ATTEST:



- ------------------------
      Secretary

                                     -viii-

<PAGE>





                            CERTIFICATE OF AMENDMENT

                                       OF

                           CERTIFICATE OF DESIGNATION

                                       OF

                             HEARTSCAN IMAGING, INC.

                             Pursuant to Section 242
                          of the Corporation Law of the
                                State of Delaware


         HeartScan Imaging,  Inc. (the "Corporation"),  a Corporation  organized
and existing under the General  Corporation  Law of the State of Delaware,  does
hereby certify as follows:

         The  Board  of  Directors  of the  Corporation,  on June 10,  1996,  by
unanimous written consent pursuant to Section 141 of the General Corporation Law
of the State of  Delaware,  adopted  resolutions  pursuant to Section 242 of the
General  Corporation  Law  of  Delaware,  setting  forth  an  amendment  to  the
Certificate  of  Designation  of Series B  Preferred  Stock and  declaring  said
amendment to be advisable. The stockholder of the Corporation duly approved said
proposed  amendment by written consent in accordance with Section 228 and 242 of
the General  Corporation  Law of the state of Delaware.  The resolution  setting
forth the amendment is as follows:

         RESOLVED,  that the  Certificate  of  Designation of Series B Preferred
Stock  of  this  Corporation  be  amended  by  restating  in  its  entirety  the
Certificate of Designation Relating to the Series B Preferred Stock of HeartScan
Imaging, Inc. to read as follows:

         RESOLVED, that pursuant to the authority expressly granted by the

                                       -i-

<PAGE>



Certificate of Incorporation,  as amended,  of the Corporation,  there is hereby
created a series of  Preferred  Stock,  $.001 par value,  consisting  of 100,000
shares,  the issuance of which is hereby  authorized,  which shall be designated
"Series  B  Preferred  Stock"  and  which  shall  have  the  following   rights,
preferences, voting powers, privileges and restrictions in addition to those set
forth in the Certificate of Incorporation, as amended, of the Corporation:

         Section 1.  Dividends.  The holders of  outstanding  shares of Series B
Preferred  shall be entitled to receive in any fiscal year, out of any assets at
the time legally  available  therefor,  dividends in cash in such amounts and at
such times as the Board of  Directors  deems  advisable.  No  dividend  or other
distribution  other  than a stock  dividend  payable  in Common  Stock  shall be
declared  or paid on any share of Common  Stock or on any share of any series or
class of Preferred  Stock unless an equal  dividend per share is declared on the
Series B Preferred  (on an  as-converted  basis) and paid at the same time as on
the Common Stock.

         Section 2.  Liquidation Preference.

                  (a) In the event of any liquidation, dissolution or winding up
of the Corporation, either voluntary or involuntary, the holders of the Series B
Preferred  shall be  entitled  on a pro rata basis to  receive,  prior to and in
preference  to any  distribution  of any of the assets or  surplus  funds of the
Corporation  to the  holders  of the Common  Stock by reason of their  ownership
thereof,  the  amount of Eighty  Dollars  ($80.00)  per share for each  share of
Series B Preferred then held by them,  and, in addition,  an amount equal to all
accrued but unpaid  dividends  on the shares of Series B Preferred  then held by
them. The  liquidation  preference of the Series B Preferred Stock shall only be
payable after payment has been made to the holders of the Corporation's Series A
Preferred Stock (hereinafter designated collectively with the Series B Preferred
Stock as the  "Preferred  Shares") of a liquidation  preference in the amount of
One Hundred Sixty Dollars  ($160.00) per share plus accrued and unpaid dividends
on the  shares of the Series A  Preferred  Stock for each such share of Series A
Preferred  held by them.  If upon  occurrence of such event the assets and funds
thus distributed among the holders of the Preferred Shares shall be insufficient
to permit the payment to such holders of the full preferential  amount, then the
entire assets and funds of the Corporation  legally  available for  distribution
shall be  distributed  ratably  among the  holders  of the  Preferred  Shares in
proportion to the preferential  amount each such holder is otherwise entitled to
receive.  After payment has been made to the holders of the Preferred  Shares of
the full amounts to which they shall be entitled as aforesaid,  and in the order
of preference  as  aforesaid,  the holders of the Common Stock and the Preferred
Shares shall share ratably all remaining assets of the Corporation in proportion
to the number of shares of Common  Stock  then held by them (on an  as-converted
basis).

                                      -ii-

<PAGE>




                  (b) For purposes of this Section 2, a merger or  consolidation
of this  Corporation with or into any other  Corporation or Corporations  (other
than a  wholly  owned  subsidiary  Corporation),  or  the  merger  of any  other
Corporation(s) into this Corporation, or the sale of all or substantially all of
the  assets  of this  Corporation,  or any  corporate  reorganization,  in which
consolidation, merger, sale of assets or reorganization the stockholders of this
Corporation receive  distributions in cash, property,  rights or securities as a
result of such consolidation, merger, sale of assets or reorganization, shall be
treated as a liquidation, dissolution or winding up of this Corporation and such
distributions shall be made in accordance with Section 2(a) above.

         Section 3. Conversion. The holders of the Series B Preferred shall have
conversion rights as follows: (the "Conversion Rights"):

                  (a) Optional and Automatic Conversion.  Each share of Series B
Preferred  shall be  convertible  at the option of the holder  thereof,  without
payment of  additional  consideration  at any time after the date of issuance of
such share at the office of the Corporation or any transfer agent for the Series
B Preferred,  into such number of fully paid and nonassessable  shares of Common
Stock,  as is  determined  by dividing  Ten Dollars  ($10.00) by the  Conversion
Price,  determined as hereinafter provided, in effect at the time of conversion.
The price at which shares of Common Stock shall be deliverable  upon  conversion
(the  "Conversion  Price")  shall  initially be One Dollar  ($1.00) per share of
Common Stock (the "Initial  Conversion  Price").  Such Initial  Conversion Price
shall be subject to adjustment as hereinafter  provided.  Each share of Series B
Preferred shall be  automatically  converted,  without the payment of additional
consideration,  into such shares of Common Stock upon the closing of a Qualified
Public  Offering.  For  purposes of this  subsection  (b), a  "Qualified  Public
Offering" means an initial public  offering of the  HeartScan's  common stock to
the general public with a post-offering  pre-proceeds fully-diluted valuation of
the equity  existing  as of June 26,  1996 (such  equity  consisting  of 100,000
issued  and  outstanding  shares  of  Series A  Preferred,  100,000  issued  and
outstanding  shares  of  Series  B  Preferred,   21,094  shares  of  issued  and
outstanding  reserved Common Stock and 448,906  reserved shares of Common Stock)
of no less than $56,000,000 for an initial public offering during the first year
following  June 26,  1996 and no less than  $78,000,000  for an  initial  public
offering  during the second year  following  June 26, 1996 for an initial public
offering  resulting  in  net  proceeds  to the  Corporation  of  not  less  than
$15,000,000,   which  initial  public   offering  is  effected   pursuant  to  a
registration statement filed with, and declared effective by, the Securities and
Exchange Commission under the Securities Act.

                  (b) Mechanics of Conversion  of Series B Preferred  Stock.  No
fractional  shares of Common Stock shall be issued upon  conversion  of Series B
Preferred. In lieu of any fractional shares to which the holder would otherwise

                                      -iii-

<PAGE>



be entitled, the Corporation shall pay cash equal to such fraction multiplied by
the then  effective  Conversion  Price.  Before any holder of Series B Preferred
shall be entitled to convert  the same into full shares of Common  Stock,  (s)he
shall surrender the certificate(s) therefor, duly endorsed, at the office of the
Corporation  or of any transfer  agent for the Series B Preferred  respectively,
and shall give  written  notice to the  Corporation  at such  office  that (s)he
elects to  convert  the same.  The  Corporation  shall,  as soon as  practicable
thereafter,  issue  and  deliver  at such  office  to such  holder  of  Series B
Preferred,  a  certificate(s),  registered  in such  names as  specified  by the
holder,  for the  number  of  shares of  Common  Stock to which  (s)he  shall be
entitled  as  aforesaid  and a check  payable to the holder in the amount of any
cash amounts  payable as the result of a conversion  into  fractional  shares of
Common Stock,  and any accrued and unpaid  dividends on the  converted  Series B
Preferred Stock respectively.  Such conversion shall be deemed to have been made
immediately  prior to the close of business on the date of such surrender of the
shares of Series B Preferred  to be  converted,  and the  person(s)  entitled to
receive  shares of Common Stock issuable upon such  conversion  shall be treated
for all purposes as the record  holder(s) of such shares of Common Stock on such
date.  If  the  conversion  is in  connection  with  an  underwritten  offer  of
securities  registered  pursuant to the Securities Act of 1933 or with any other
transaction,  the conversion may, at the option of any holder tendering Series B
Preferred  for  conversion,  be  conditioned  upon  the  closing  of the sale of
securities pursuant to such offering or the closing of the other transaction, in
which event the holder  entitled to receive the Common Stock  issuable upon such
conversion of the Series B Preferred  shall not be deemed to have converted such
Series B  Preferred  until  immediately  prior to the  closing  of such  sale of
securities or other transaction.

                  (c)  Adjustments to Conversion Price.

                           (i) In the  event  the  outstanding  shares of Common
Stock shall be combined or consolidated,  by reclassification or otherwise, into
a lesser  number  of  shares of Common  Stock,  the  Conversion  Price in effect
immediately prior to such combination or consolidation shall,  concurrently with
the  effectiveness  of such  combination or  consolidation,  be  proportionately
increased.

                           (ii) In the event the  Corporation  shall  declare or
pay any dividend on the Common Stock payable in Common Stock or in the event the
outstanding shares of Common Stock shall be subdivided,  by  reclassification or
otherwise  than by payment of a dividend in Common Stock,  into a greater number
of shares of Common Stock, the Conversion Price in effect  immediately  prior to
such dividend or subdivision shall be proportionately decreased:


                                    (A) in the case of any such dividend,

                                      -iv-

<PAGE>



immediately after the close of business on the record date for the determination
of holders of any class of securities entitled to receive such dividend, or

                                    (B) in the case of any such subdivision,  at
the close of business on the date immediately  prior to the date upon which such
corporate action becomes effective.

         If such record date shall have been fixed and such  dividend  shall not
have been fully paid on the date fixed therefor,  the adjustment previously made
in the  Conversion  Price which  became  effective  on such record date shall be
cancelled as of the close of business on such record date,  and  thereafter  the
Conversion  Price  shall be  adjusted  as of the time of actual  payment of such
dividend.

                  (d) No Impairment.  The Corporation  will not, by amendment of
its  Certificate of  Incorporation  or through any  reorganization,  transfer of
assets, consolidation,  merger, dissolution,  issue or sale of securities or any
other voluntary action,  avoid or seek to avoid the observance or performance of
any of the terms to be observed or performed  hereunder by the  Corporation  but
will at all times in good faith assist in the carrying out of all the provisions
of this  Section 3 and in the taking of all such action as may be  necessary  or
appropriate  in order to protect  the  Conversion  Rights of the  holders of the
Series B Preferred against impairment.

         The Corporation  shall from time to time in accordance with the laws of
the State of Delaware  increase the authorized  amount of its Common Stock if at
any time the number of Common Stock shares remaining  unissued and available for
issuance shall not be sufficient to permit  conversion of the Series B Preferred
as appropriate.

                  (e) Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment  of the Conversion  Price pursuant to this Section 3,
the  Corporation  at its expense  shall  promptly  compute  such  adjustment  or
readjustment  in accordance  with the terms hereof and furnish to each holder of
Series B Preferred as appropriate a certificate setting forth such adjustment or
readjustment  and  showing in detail the facts  upon  which such  adjustment  or
readjustment is based.  The Corporation  shall,  upon the written request at any
time of any holder of Series B  Preferred,  furnish or cause to be  furnished to
such  holder  a  like  certificate   setting  forth  (i)  such  adjustments  and
readjustments,  (ii) the Conversion  Price at the time in effect,  and (iii) the
number of shares of Common Stock and the amount, if any, of other property which
at the time would be received upon the conversion of Series B Preferred.

                  (f)  Reservation of Common Stock. The Corporation shall at all
times have reserved from its authorized and unissued Common Stock a sufficient

                                       -v-

<PAGE>



number of shares of Common Stock to satisfy the conversion  rights of the shares
of Series B Preferred Stock.

                  (g) Notices of Record Date. In the event that this Corporation
shall propose at any time:

                           (i) to declare any dividend or distribution  upon its
Common Stock, whether in cash, property,  stock or other securities,  whether or
not a  regular  cash  dividend  and  whether  or not out of  earnings  or earned
surplus;

                           (ii)  to  offer  for  subscription  pro  rata  to the
holders  of any class or series of its stock any  additional  shares of stock of
any class or series or other rights;

                           (iii)   to    effect    any    reclassification    or
recapitalization  of its  Common  Stock  outstanding  involving  a change in the
Common Stock; or

                           (iv) to merge or  consolidate  with or into any other
Corporation,  or sell, lease or convey all or substantially  all its property or
business,  or to liquidate,  dissolve or wind up; then, in connection  with each
such event, this Corporation shall send to the holders of the Series B Preferred
shares:

                                    (1) at least 30 days' prior  written  notice
of the date on which a record shall be taken for such dividend,  distribution or
subscription  rights  (and  specifying  the date on which the  holders of Common
Stock shall be entitled thereto) or for determining rights to vote in respect of
the matters referred to in (iii) and (iv) above; and

                                    (2) in the case of the  matters  referred to
in (iii) and (iv) above, at least 30 days' prior written notice of the date when
the same shall take place (and  specifying,  if  practicable,  or estimating the
date on which the holders of Common  Stock  shares shall be entitled to exchange
their Common Stock shares for securities or other property  deliverable upon the
occurrence of such event).

         Each such written  notice  shall be given by first class mail,  postage
prepaid,  addressed to the holders of Series B Preferred at the address for each
such holder as shown on the books of this Corporation.

         Section 4. Voting  Rights.  Except as otherwise  required by law,  each
share of Series B Preferred Stock issued and outstanding shall have the right to
vote with the  holders of Common  Stock on all  matters,  each share of Series B
Preferred  Stock having that number of votes equal to the number of Common Stock
shares into which the Series B Preferred is convertible as adjusted from

                                      -vi-

<PAGE>



time to time.

         Section 5.  Residual  Rights.  All rights  accruing to the  outstanding
shares of this  Corporation  not expressly  provided for to the contrary  herein
shall be vested in the Common Stock.

         Section 6. No reissuance  of Series A Preferred.  No shares of Series A
Preferred  acquired  by this  Corporation  by  reason of  redemption,  purchase,
conversion or otherwise, shall be reissued.

         Section 7. Covenants.  In addition to any other rights provided by law,
so long as any Series B Preferred shall be outstanding,  this Corporation  shall
not,  without first  obtaining the  affirmative  vote or written  consent of the
holders  of not less  than  two-thirds  of such  outstanding  shares of Series A
Preferred:

                  (a) Amend or repeal any provision of, or add any provision to,
this  Corporation's  Certificate of Incorporation or Bylaws if such action would
alter or  change  the  preferences,  rights,  privileges  or  powers  of, or the
restrictions  provided for the benefit of, any Series B Preferred or increase or
decrease the number of Series B Preferred authorized hereby;

                  (b)  reclassify  any  Common  Stock  into  shares  having  any
preference or priority as to dividends or assets superior to or on a parity with
any such preference or priority of the Series B Preferred;

                  (c) apply any of its  assets  to the  redemption,  retirement,
purchase  or  acquisition  directly  or  indirectly.   through  subsidiaries  or
otherwise, of any Common Stock, except from officers,  directors or employees of
or  consultants  to this  Corporation or its  subsidiaries  upon  termination of
employment,  directorship or consulting  pursuant to the terms of stock purchase
agreements  or  restricted  stock  purchase  agreements  entered  into with such
officers, directors, employees or consultants.


                                      -vii-

<PAGE>




         IN WITNESS  WHEREOF,  the Corporation has caused its seal to be affixed
hereto and this  Certificate  of  Amendment  to be signed by its  President  and
attested by its Secretary this 10th day of June, 1996.

                                  HEARTSCAN IMAGING, INC.

                                  BY_______________________
                                           President



ATTEST:



- ------------------------
      Secretary


                                     -viii-

<PAGE>



                                    EXHIBIT E


               Form of Opinion of Counsel to Imatron and HeartScan










                                  June 24, 1996




To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement

Ladies and Gentlemen:

         We have  acted as counsel to  Imatron  Inc.,  a New Jersey  corporation
("Imatron") and HeartScan Imaging, Inc., a Delaware corporation ("HeartScan") in
connection  with the  execution  and  delivery of that  certain  Stock  Purchase
Agreement dated as of June 24, 1996 (the "Purchase Agreement").  This opinion is
furnished to you pursuant to Section 11.6 of the Purchase Agreement. Capitalized
terms used herein and not otherwise defined herein are used herein as defined in
the Purchase Agreement.

         For purposes of this opinion, we have examined the following:


                           (a) A copy of the Purchase Agreement;

                           (b) A copy of the  Certificate  of  Incorporation  of
Imatron,  as amended,  certified by the Secretary of State of New Jersey on June
10, 1996;

                           (c) A copy of the  Certificate  of  Incorporation  of
HeartScan,  as amended,  certified by the Secretary of State of Delaware on June
17, 1996;

                           (d) A copy of the By-laws of Imatron  certified to us
by an officer of  Imatron as being  complete  and in full force and effect as of
the date of this opinion.


<PAGE>


To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement
June 24, 1995
Page 2




                           (e) A copy of the By-laws of  HeartScan  certified to
us by an officer of HeartScan as being  complete and in full force and effect as
of the date of this opinion.

                           (f) Records  certified to us by an officer of Imatron
constituting all records of proceedings and actions of the board of directors of
Imatron relating to the transaction contemplated by the Purchase Agreement.

                           (g)  Records   certified  to  us  by  an  officer  of
HeartScan  constituting  all records of proceedings  and actions of the board of
directors and shareholders of HeartScan relating to the transaction contemplated
by the Purchase Agreement.

         We have assumed the genuineness and  authenticity of all signatures and
the  authenticity  of  all  documents  submitted  to us as  originals,  and  the
conformity with the originals of all documents submitted to us as copies and the
accuracy and  completeness  and authenticity of certificates of public officials
and of  all  corporate  records  and  information  made  available  to us by the
Company. We have assumed with respect to the Purchasers, that each has the power
to enter into and perform all of its obligations  under the Purchase  Agreement,
the  due  authorization  by the  Purchaser  of all  requisite  actions,  the due
execution  and delivery of the  Purchase  Agreement  by the  Purchasers  and the
enforceability of the Purchase Agreement against the Purchasers.

         In rendering  this  opinion,  we relied as to factual  matters upon the
certificates  referred to above.  We have also  examined  originals or copies of
such corporate documents or records of the Company as we have deemed appropriate
for the opinions expressed herein. Where we render an opinion "to our knowledge"
or with  respect to  matters  "of which we have  knowledge,"  it is based on the
actual  knowledge of attorneys in this firm who are currently  involved with the
transactions  contemplated  by the Purchase  Agreement and a review of the above
certificates.  With your  consent we have not examined any records of any court,
administrative  tribunal or other similar entity in connection  with our opinion
in  Paragraph 7 below.  While  nothing has come to our  attention  leading us to
question  or giving us  reasonable  grounds to  question  the  accuracy  of such
certificates or information,  we have not, except as specifically  noted in this
opinion, made any independent review or investigation.

         Based on the foregoing, we are of the opinion that:

         (a) Imatron is a corporation  duly organized,  validly  existing and in
good standing  under the laws of the New Jersey and has all requisite  power and
authority to own, lease and


<PAGE>


To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement
June 24, 1995
Page 3



operate  its  properties  and assets and to conduct  its  business  as now being
conducted.  HeartScan is a corporation  duly organized,  validly existing and in
good  standing  under the laws of the Delaware and has all  requisite  power and
authority to own, lease and operate its properties and assets and to conduct its
business as now being conducted.

         (b)  Imatron  and  HeartScan  have all  requisite  corporate  power and
authority to enter into the Purchase Agreement, to sell the Shares, and to carry
out their respective  obligations under the Purchase  Agreement.  The execution,
delivery and  performance  of the Purchase  Agreement have been duly and validly
authorized by all  requisite  corporate  proceedings  on the part of Imatron and
HeartScan  respectively.  The Purchase  Agreement when executed and delivered by
Imatron and HeartScan,  shall constitute valid and binding  obligations of each,
subject to the  following  qualifications:  (i) that certain  provisions  of the
Agreement may not be enforceable, but that such enforceability will not, subject
to the other exceptions,  qualifications, and limitations in this Letter, render
the contract invalid as a whole or  substantially  interfere with realization of
the principal  benefits  provided by the Agreement;  (ii) subject to the laws of
general application relating to bankruptcy, insolvency and the relief of debtors
and rules of law  governing  specific  performance,  injunctive  relief or other
equitable  remedies;  and (iii) except to the extent that Sections 9.6, 9.10 and
10.7 may be limited by public policy and applicable judicial decisions.
         (c) The execution and delivery of the Purchase Agreement by Imatron and
HeartScan  do  not,  and  the  consummation  by  Imatron  and  HeartScan  of the
transactions  contemplated  thereby  will not  result  in or  constitute:  (a) a
default,  breach or violation of or under the  Certificate of  Incorporation  or
Bylaws of either;  (b) to our  knowledge,  a default,  breach or violation of or
under any  mortgage,  deed of  trust,  indenture,  note,  bond,  license,  lease
agreement or other instrument or obligation to which either Imatron or HeartScan
is a party or by which any of their  respective  properties or assets are bound;
(c) to our  knowledge,  a violation of any  statute,  rule,  regulation,  order,
judgement  or decree of any court,  public  body or  authority  by which  either
Imatron or HeartScan or any of their respective  properties or assets are bound;
(d) to our knowledge an event which (with notice or lapse of time or both) would
permit any person to  terminate,  accelerate  the  performance  required  by, or
accelerate  the  maturity  of any  indebtedness  or  obligation  of  Imatron  or
HeartScan  under any  Agreement or  commitment  to which either is a party or by
which  the  either is bound or by which any of their  respective  properties  or
assets are bound; (e) to our knowledge,  the creation or imposition of any lien,
charge  or  encumbrance  on any  property  of  Imatron  or  HeartScan  under any
agreement or  commitment  to which either is a party or by which either is bound
or by which any of their  respective  properties or assets are bound;  or (f) to
our  knowledge an event which would  require any consent  under any agreement or
commitment to which Imatron or HeartScan is a party or


<PAGE>


To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement
June 24, 1995
Page 4



by  which the either is bound or by which  any of their respective properties or
assets are bound.

         (d)  The  authorized   capital  stock  of  Imatron   consists  of:  (a)
100,000,000  shares of Common Stock,  of which (i) 76,268,990  shares are issued
and  outstanding,  (ii)  3,687,560  shares have been reserved for issuance under
outstanding  warrants,  (iii)  6,648,209  shares have been reserved for issuance
under various stock plans, and (iii) 10,666,667 shares are reserved for exchange
hereunder;  and (b) 10,000,000  shares of preferred stock of which (i) 2,632,813
shares have been designated  "Series A Preferred Stock," none of which is issued
and  outstanding,  and (ii)  380,000  shares  have  been  designated  "Series  B
Preferred Stock," none of which is issued and outstanding.

         (e)  The  authorized  capital  stock  of  HeartScan  consists  of:  (a)
4,000,000  shares of Common  Stock,  of which (i)  21,094  shares are issued and
outstanding,  (ii) 448,906 shares have been reserved for issuance pursuant stock
option and other plans, (iii) 30,000 shares have been reserved for issuance upon
the exercise of warrants to be issued in  connection  with the purchase and sale
of the Shares,  and (iv)  2,000,000  shares have been reserved for issuance upon
conversion of the  outstanding  Series A Preferred  Stock and Series B Preferred
Stock;  and (b) 1,000,000  shares of preferred stock of which (i) 200,000 shares
have been designated  "Series A Preferred Stock" and of which 100,000 are issued
and outstanding, and (ii) 100,000 shares of which have been designated "Series B
Preferred Stock" and of which all 100,000 shares are issued and outstanding.

         (f) The HeartScan  Preferred  Shares to be transferred at Closing,  and
the HeartScan common shares into which those Shares can be converted,  have been
duly authorized by all necessary corporate action on the part of HeartScan.

         (g) To  our  knowledge,  there  is no  suit,  claim,  investigation  or
proceeding  pending or threatened  against  Imatron or HeartScan which questions
the  validity  of the  Purchase  Agreement  or any  action  taken or to be taken
pursuant  thereto.  To our  knowledge,  except as set forth on  Exhibit B to the
Purchase Agreement, there is no action, suit, claim, investigation or proceeding
pending or threatened, against or involving Imatron or HeartScan or any of their
properties  or  assets.  To our  knowledge,  there  are no  outstanding  orders,
judgments,   injunctions,  awards,  or  decrees  of  any  court,  arbitrator  or
governmental or regulatory body against Imatron or HeartScan.

         (h) Subject to the accuracy of the Purchasers'  representations  as set
forth in the Purchase  Agreement,  the offer, sale and issuance of the Shares to
be sold in  conformity  with the  terms  of the  Purchase  Agreement  constitute
transactions exempt from the registration


<PAGE>


To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement
June 24, 1995
Page 5



requirements of Section 5 of the Securities Act of 1933, as amended,  and of the
California Corporate Securities Law of 1968.

         (i)  Except as set forth on  Exhibit B to the  Purchase  Agreement  and
except for the filing of any notice prior or  subsequent to the Closing that may
be  required  under  applicable   state  and/or  federal   securities  laws,  no
authorization,   consent,   approval,   license,   exemption  of  or  filing  or
registration  with any  court or  governmental  department,  commission,  board,
bureau, agency or instrumentality,  domestic or foreign, is or will be necessary
for, or in connection  with,  the execution and delivery by Imatron or HeartScan
of the Purchase Agreement,  and for the offering, sale, execution or delivery of
the  Shares,  or for the  performance  by Imatron of its  obligations  under the
Purchase Agreement.  Notwithstanding the foregoing,  no opinion is rendered with
respect to whether HeartScan currently has or will in fact be able to obtain any
or all of the authorizations, consents, approvals licenses or registrations that
may in the future be necessary to implement it business plan.


         In  rendering  the  foregoing  opinions,   we  have  assumed,   without
verification, the following:

         (A) All  representations,  warranties  and  covenants  contained in the
Purchase Agreement are accurate; provided, however, that any statement set forth
in a  representation  or  warranty  for which an opinion is  rendered  herein is
excluded from the scope of this assumption;

         (B) There are no oral agreements  among the parties which conflict with
or materially amend or supplement the provisions of the Purchase Agreement;

         (C) The  Purchasers  will  comply  with  their  obligations  under  the
Purchase  Agreement and with all requisite  legal  procedures in connection with
their rights in respect of such documents;

         (D) That any wire transfers, drafts or checks tendered by any Purchaser
will be honored; and

         (E) If a Purchaser is a corporation or other entity,  it has have filed
any  required  state  franchise,  income or similar tax returns and has paid any
required state franchise, income or similar taxes.



<PAGE>


To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement
June 24, 1995
Page 6



         With respect to assumptions  (A) and (B), above, we confirm to you that
(i) we  have  no  knowledge  that  any of the  representations,  warranties  and
covenants  contained in the Purchase Agreement are inaccurate,  and (ii) we have
no knowledge of any oral  agreements  among the parties  which  conflict with or
materially amend or supplement the provisions of the Purchase Agreement.

         Furthermore,   in  rendering   the  foregoing   opinion,   we  make  no
representation and express no opinion as to:

         a. The  enforceability of the  indemnification  provisions set forth in
the Purchase Agreement;

         b. The  compliance  or  noncompliance  by  Imatron  or  HeartScan  with
applicable antifraud statues under the rules and regulations applicable to state
and federal laws concerning the issuance of securities;

         c. The  enforceability  of any covenant by which a person agrees not to
compete with any other person.

         The  foregoing  opinions  are further  qualified to the extent that the
validity or  enforceability  of any  provisions  of the Purchase  Agreement  are
subject to the following:

         (i) Bankruptcy, insolvency, reorganization, moratorium, rehabilitation,
liquidation,  conservatorship,   receivership  or  other  similar  laws  now  or
hereafter in effect relating to creditors' rights generally;

         (ii)  Limitations  on  the  availability  of  the  remedy  of  specific
performance  and  injunctive  and other forms of  equitable  relief by reason of
equitable  defenses and the  discretion  of courts  before which any  proceeding
therefore may be brought;

         (iii)  The  compliance  or  non-compliance  with  applicable  state and
federal  anti-fraud  or   misrepresentation   statues,   rules  and  regulations
concerning the issuance of securities;

         (iv) Limitations on the  enforceability  of contracts or obligations by
entities  deemed to be doing  business  in the State of  California  which  have
failed to qualify to do business in the State of California  or whose  authority
to conduct business in the State of California has been suspended;


<PAGE>


To Each of the Purchasers Listed
on Exhibit A to the Purchase Agreement
June 24, 1995
Page 7



         (v)  Limitations  based on state law and public  policy  regarding  the
enforceability  of express or implied  waivers  including,  without  limitation,
waivers of rights, claims or defenses;

         (vi) Limitations on the enforceability of a requirement that provisions
of a document  may only be amended or waived in  writing,  to the extent that an
oral agreement modifying provisions of the document has been performed;

         (vii)  Limitations on the  effectiveness of  "severability"  provisions
depending on the materiality of the unenforceable provision to the document as a
whole and the undertakings of the parties thereunder;

         (viii) The effect of California  court  decisions  which have held that
certain provisions of agreements are unenforceable  where a party's  enforcement
of such  provisions  under the  circumstances  would violate the party's implied
covenant of good faith and fair dealing;

         (ix) The effect of  California,  federal  law or  equitable  principles
which limit the amount of  attorneys'  fees that can be recovered  under certain
circumstances.

         The opinion set forth  herein is as of the date of this  opinion and we
disclaim any  undertaking  to update this opinion based upon any changes in fact
or law of which we may become aware.

         As you are aware,  we are admitted to practice law only in the State of
California.  Except with respect to the due  incorporation  and good standing of
Imatron and  HeartScan,  we express no opinion on any laws  (including  any laws
relating to conflicts of laws) other than the federal laws of the United  States
of America  and the laws of the State of  California.  With your  permission  we
assume, without investigation, that the laws of Delaware and California, and the
interpretations  thereof, are the same. The preceding opinion is based solely on
such laws.

         This  opinion is for your benefit and may not be relied on by any other
person, or by you in any other context or for any other purpose,  nor may copies
hereof be delivered to any other person without our prior written consent.

                                          Very truly yours,







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