<PAGE>   1
                                                                     EXHIBIT 4.9




THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, PLEDGED OR
OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT
OR PURSUANT TO RULE 144 OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE
CORPORATION AND ITS COUNSEL THAT SUCH REGISTRATION IS NOT REQUIRED.

                            WARRANT TO PURCHASE STOCK

Corporation:              ALLIANCE MEDICAL CORPORATION, A DELAWARE CORPORATION

Number of Shares:         85,000

Class of Stock:           COMMON

Initial Exercise Price:   $1.10 PER SHARE

Issue Date:               APRIL 24, 2000

Expiration Date:          APRIL 24, 2007 (Subject to Article 4.1)


         THIS WARRANT CERTIFIES THAT, in consideration of the payment of $1.00
and for other good and valuable consideration, IMPERIAL BANCORP or registered
assignee ("Holder") is entitled to purchase the number of fully paid and
nonassessable shares of the class of securities (the "Shares") of the
corporation (the "Company") at the initial exercise price per Share (the
"Warrant Price") all as set forth above and as adjusted pursuant to Article 2 of
this Warrant, subject to the provisions and upon the terms and conditions set
forth of this Warrant.

ARTICLE 1. EXERCISE

         1.1 Method of Exercise. Holder may exercise this Warrant by delivering
this Warrant and a duly executed Notice of Exercise in substantially the form
attached as Appendix 1 to the principal office of the Company. Unless Holder is
exercising the conversion right set forth in Section 1.2, Holder shall also
deliver to the Company a check for the aggregate Warrant Price for the Shares
being purchased.

         1.2 Conversion Right. In lieu of exercising this Warrant as specified
in Section 1.1, Holder may from time to time convert this Warrant, in whole or
in part, into a number of Shares determined by dividing (a) the aggregate fair
market value of the Shares or other securities otherwise issuable upon exercise
of this Warrant minus the aggregate Warrant Price of such Shares by (b) the fair
market value of one Share. The fair market value of the Shares shall be
determined pursuant to Section 1.5.

         1.3 Alternative Stock Appreciation Right. [Intentionally Deleted.]

         1.4 Right to Put Warrant. At Holder's option, in lieu of exercising its
rights as set forth in Sections 1.1 or 1.2, Holder shall have the right, which
may be exercised by Holder no earlier than the date that is five (5) years after
the Issue Date, to require the Company to purchase the Warrant under the
circumstances set forth on Exhibit A.
<PAGE>   2
         1.5 Fair Market Value. If the Shares are traded regularly in a public
market, the fair market value of the Shares shall be the closing price of the
Shares (or the closing price of the Company's stock into which the Shares are
convertible) reported for the business day immediately before Holder delivers
its Notice of Exercise to the Company. If the Shares are not regularly traded in
a public market, the Board of Directors of the Company shall determine fair
market value in its reasonable good faith judgment. The foregoing
notwithstanding, if Holder advises the Board of Directors in writing that Holder
disagrees with such determination, then the Company and Holder shall promptly
agree upon a reputable investment banking firm to undertake such valuation. If
the valuation of such investment banking firm is greater than that determined by
the Board of Directors, then all fees and expenses of such investment banking
firm shall be paid by the Company. In all other circumstances, such fees and
expenses shall be paid by Holder.

         1.6 Delivery of Certificate and New Warrant. Promptly after Holder
exercises or converts this Warrant, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

         1.7 Replacement of Warrants. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, or surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant, a
new warrant of like tenor.

         1.8 Repurchase on Sale, Merger, or Consolidation of the Company.

                  1.8.1 "Acquisition". For the purpose of this Warrant,
"Acquisition" means any sale, license, or other disposition of all or
substantially all of the assets (including intellectual property) of the
Company, or any reorganization, consolidation, or merger of the Company where
the holders of the Company's securities before the transaction beneficially own
less than 50% of the outstanding voting securities of the surviving entity after
the transaction.

                  1.8.2 Assumption of Warrant. If upon the closing of any
Acquisition the successor entity assumes the obligations of this Warrant, then
this Warrant shall be exercisable for the same securities, cash, and property as
would be payable for the Shares issuable upon exercise of the unexercised
portion of this Warrant as if such Shares were outstanding on the record date
for the Acquisition and subsequent closing. The Warrant Price shall be adjusted
accordingly. The Company shall use reasonable efforts to cause the surviving
corporation to assume the obligations of this Warrant.

                  1.8.3 Nonassumption. If upon the closing of any Acquisition
the successor entity does not assume the obligations of this Warrant and Holder
has not otherwise exercised this Warrant in full, then the unexercised portion
of this Warrant shall be deemed to have been automatically converted pursuant to
Section 1.2 and thereafter Holder shall participate in the Acquisition on the
same terms as other holders of the same class of securities of the Company.



                                       2
<PAGE>   3
                  1.8.4 Purchase Right. Notwithstanding the foregoing, at the
election of Holder, the Company shall purchase the unexercised portion of this
Warrant for cash upon the closing of any Acquisition for an amount equal to (a)
the fair market value of any consideration that would have been received by
Holder in consideration of the Shares had Holder exercised the unexercised
portion of this Warrant immediately before the record date for determining the
shareholders entitled to participate in the proceeds of the Acquisition, less
(b) the aggregate Warrant Price of the Shares, but in no event less than zero.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

         2.1 Stock Dividends, Splits, Etc. If the Company declares or pays a
dividend on its common stock payable in common stock, or other securities,
subdivides the outstanding common stock into a greater amount of common stock,
then upon exercise of this Warrant, for each Share acquired, Holder shall
receive, without cost to Holder, the total number and kind of securities to
which Holder would have been entitled had Holder owned the Shares of record as
of the date the dividend or subdivision occurred.

         2.2 Reclassification, Exchange or Substitution. Upon any
reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event. Such an event shall include any automatic conversion of the
outstanding or issuable securities of the Company of the same class or series as
the Shares to common stock pursuant to the terms of the Company's Articles of
Incorporation upon the closing of a registered public offering of the Company's
common stock. The Company or its successor shall promptly issue to Holder a new
Warrant for such new securities or other property. The new Warrant shall provide
for adjustments which shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Article 2 including, without limitation,
adjustments to the Warrant Price and to the number of securities or property
issuable upon exercise of the new Warrant. The provisions of this Section 2.2
shall similarly apply to successive reclassifications, exchanges, substitutions,
or other events.

         2.3 Adjustments for Combinations, Etc. If the outstanding Shares are
combined or consolidated, by reclassification or otherwise, into a lesser number
of shares, the Warrant Price shall be proportionately increased.

         2.4 Adjustments for Diluting Issuances. The Warrant Price and the
number of Shares issuable upon exercise of this Warrant shall be subject to
adjustment, from time to time, in the manner set forth on Exhibit B, if
attached, in the event of Diluting Issuances (as defined on Exhibit B).

         2.5 No Impairment. The Company shall not, by amendment of its Articles
of Incorporation or through a 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 under this Warrant by the Company, but shall at all times
in good faith assist in carrying out all the provisions of this

                                       3
<PAGE>   4
Article 2 and in taking all such action as may be necessary or appropriate to
protect Holder's rights under this Article against impairment. If the Company
takes any action affecting the Shares or its common stock other than as
described above that adversely affects Holder's rights under this Warrant, the
Warrant Price shall be adjusted downward and the number of Shares issuable upon
exercise of this Warrant shall be adjusted upward in such a manner that the
aggregate Warrant Price of this Warrant is unchanged.

         2.6 Certificate as to Adjustments. Upon each adjustment of the Warrant
Price, the Company at its expense shall promptly compute such adjustment, and
furnish Holder with a certificate of its Chief Financial Officer setting forth
such adjustment and the facts upon which such adjustment is based. The Company
shall, upon written request, furnish Holder a certificate setting forth the
Warrant Price in effect upon the date thereof and the series of adjustments
leading to such Warrant Price.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

         3.1 Representations and Warranties. The Company hereby represents and
warrants to the Holder as follows:

                  (a) The initial Warrant Price referenced on the first page of
this Warrant is not greater than the fair market value of the Shares as of the
date of this Warrant.

                  (b) All Shares which may be issued upon the exercise of the
purchase right represented by this Warrant, and all securities, if any, issuable
upon conversion of the Shares, shall, upon issuance, be duly authorized, validly
issued, fully paid and nonassessable, and free of any liens and encumbrances
except for restrictions on transfer provided for herein or under applicable
federal and state securities laws.

         3.2 Notice of Certain Events. If the Company proposes at any time (a)
to declare any dividend or distribution upon its common stock, whether in cash,
property, stock, or other securities and whether or not a regular cash dividend;
(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 common stock; (d) to
merge or consolidate with or into any other corporation, or sell, lease,
license, or convey all or substantially all of its assets, or to liquidate,
dissolve or wind up; or (e) offer holders of registration rights the opportunity
to participate in an underwritten public offering of the Company's securities
for cash, then, in connection with each such event, the Company shall give
Holder (1) at least 20 days prior written notice of the date on which a record
will be taken for such dividend, distribution, or subscription rights (and
specifying the date on which the holders of common stock will be entitled
thereto) or for determining rights to vote, if any, in respect of the matters
referred to in (c) and (d) above; (2) in the case of the matters referred to in
(c) and (d) above at least 20 days prior written notice of the date when the
same will take place (and specifying the date on which the holders of common
stock will be entitled to exchange their common stock for securities or other
property deliverable upon the occurrence of such event); and (3) in the case of
the matter referred to in (e) above, the same notice as is given to the holders
of such registration rights.



                                       4
<PAGE>   5
         3.3 Information Rights. So long as the Holder holds this Warrant and/or
any of the Shares, the Company shall deliver to the Holder (a) promptly after
mailing, copies of all communiques to the shareholders of the Company, (b)
within ninety (90) days after the end of each fiscal year of the Company, the
annual audited financial statements of the Company certified by independent
public accountants of recognized standing and (c) within forty-five (45) days
after the end of each of the first three quarters of each fiscal year, the
Company's quarterly, unaudited financial statements.

         3.4 Registration Under Securities Act of 1933, as amended. The Company
agrees that the Shares shall be subject to the registration rights set forth on
Exhibit C.

ARTICLE 4. MISCELLANEOUS.

         4.1 Term: Notice of Expiration. This Warrant is exercisable, in whole
or in part, at any time and from time to time on or before the Expiration Date
set forth above. The Company shall give Holder written notice of Holder's right
to exercise this Warrant in the form attached as Appendix 2 not more than 90
days and not less than 30 days before the Expiration Date. If the notice is not
so given, the Expiration Date shall automatically be extended until 30 days
after the date the Company delivers the notice to Holder.

         4.2 Legends. This Warrant and the Shares (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) shall be
imprinted with a legend in substantially the following form:

         THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
         AS AMENDED, AND MAY NOT BE SOLD, PLEDGED OR OTHERWISE TRANSFERRED
         WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT OR PURSUANT TO
         RULE 144 OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE
         CORPORATION AND ITS COUNSEL THAT SUCH REGISTRATION IS NOT REQUIRED.

         4.3 Compliance with Securities Laws on Transfer. This Warrant and the
Shares issuable upon exercise of this Warrant (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) may not be
transferred or assigned in whole or in part without compliance with applicable
federal and state securities laws by the transferor and the transferee
(including, without limitation, the delivery of investment representation
letters and legal opinions reasonably satisfactory to the Company). The Company
shall use its best efforts to not require Holder to provide an opinion of
counsel if the transfer is to an affiliate of Holder or if there is no material
question as to the availability of current information as referenced in Rule
144(c), Holder represents that it has complied with Rule 144(d) and (e) in
reasonable detail, the selling broker represents that it has complied with Rule
144(f), and the Company is provided with a copy of Holder's notice of proposed
sale.

         4.4 Transfer Procedure. Subject to the provisions of Section 4.3,
Holder may transfer all or part of this Warrant or the Shares issuable upon
exercise of this Warrant (or the securities issuable, directly or indirectly,
upon conversion of the Shares, if any) by giving the Company notice of the
portion of the Warrant being transferred setting forth the name, address and


                                       5
<PAGE>   6
taxpayer identification number of the transferee and surrendering this Warrant
to the Company for reissuance to the transferee(s) (and Holder, if applicable).
Unless the Company is filing financial information with the SEC pursuant to the
Securities Exchange Act of 1934, the Company shall have the right to refuse to
transfer any portion of this Warrant to any person who directly competes with
the Company.

         4.5 Notices. All notices and other communications from the Company to
the Holder, or vice versa, shall be deemed delivered and effective when given
personally or mailed by first-class registered or certified mail, postage
prepaid, at such address as may have been furnished to the Company or the
Holder, as the case may be, in writing by the Company or such Holder from time
to time.

         4.6 Waiver. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

         4.7 Attorneys' Fees. In the event of any dispute between the parties
concerning the terms and provisions of this Warrant, the party prevailing in
such dispute shall be entitled to collect from the other party all costs
incurred in such dispute, including reasonable attorneys' fees.

         4.8 Governing Law. This Warrant shall be governed by and construed in
accordance with the laws of the State of Arizona, without giving effect to its
principles regarding conflicts of law.

                                        ALLIANCE MEDICAL CORPORATION,
                                        a Delaware corporation


                                        By:
                                               ---------------------------------

                                        Name:
                                               ---------------------------------

                                        Title:
                                               ---------------------------------


                                        By:
                                               ---------------------------------

                                        Name:
                                               ---------------------------------

                                        Title:
                                               ---------------------------------




                                       6
<PAGE>   7
                                   APPENDIX 1

                               NOTICE OF EXERCISE

         1. The undersigned hereby elects to purchase __________ shares of the
Common Stock of Alliance Medical Corporation pursuant to the terms of the
attached Warrant, and tenders herewith payment of the purchase price of such
shares in full.

         2. The undersigned hereby elects to convert the attached Warrant into
Shares in the manner specified in the Warrant. This conversion is exercised with
respect to ________ of the Shares covered by the Warrant.

         [Strike paragraph that does not apply.]

         3. Please issue a certificate or certificates representing said shares
in the name of the undersigned or in such other name as is specified below:

                           Chief Financial Officer
                           Controllers Department
                           Imperial Bancorp
                           P.O.  Box 92991
                           Los Angeles, CA 90009
                           Or Registered Assignee

         4. The undersigned represents it is acquiring the shares solely for its
own account and not as a nominee for any other party and not with a view toward
the resale or distribution thereof except in compliance with applicable
securities laws.

IMPERIAL BANCORP or Registered Assignee



---------------------------------------
(Signature)


---------------------------------------
(Date)




                                       7
<PAGE>   8
                                   APPENDIX 2

                     NOTICE THAT WARRANT IS ABOUT TO EXPIRE

                                ____________ 2000

Chief Financial Officer
Controllers Department
Imperial Bancorp
P.O.  Box 92991
Los Angeles, CA 90009
Or Registered Assignee

Gentleperson:

         This is to advise you that the Warrant issued to you described below
will expire on _____________ 2007.

Issuer:

Issue Date:                             April , 2000

Class of Security Issuable:             Common

Exercise Price Per Share:               $1.10

Number of Shares Issuable:              85,000

Procedure for Exercise:

         Please contact [name of contact person at (phone number)] with any
questions you may have concerning exercise of the Warrant. This is your only
notice of pending expiration.

         Alliance Medical Corporation,
         a Delaware corporation

         By:
             ---------------------------

         Its:
             ---------------------------




                                       8
<PAGE>   9
                                    EXHIBIT A

                                    Put Right

         Subject to the next sentence, upon written notice to the Company,
Holder shall have the right (the "Put Right") to require that the Company
purchase the Warrant from Holder in consideration of the Company's payment to
Holder (due seven days after receipt of Holder's written notice) of an amount
equal to the Fair Market Value of the Shares less the Warrant exercise price.
The foregoing notwithstanding, Holder may only exercise the Put Right during the
first to occur of the following periods:

         1. On or after the date that is five (5) years after the Issue Date; or

         2. The 20 day period ending on the closing of the merger, consolidation
or sale of assets of the Company; or

         3. The 20 day period ending on the liquidation, dissolution or winding
up of the Company.




                                       9
<PAGE>   10
                                    EXHIBIT B

                                IMPERIAL BANCORP
                             ANTIDILUTION AGREEMENT

         This Antidilution Agreement is entered into as of April __, 2000, by
and between Imperial Bancorp ("Purchaser") and Alliance Medical Corporation, a
Delaware corporation ("the Company").

                                    RECITALS

         A. Concurrently with the execution of this Antidilution Agreement, the
Purchaser is purchasing from the Company a Warrant to Purchase Stock (the
"Warrant") pursuant to which Purchaser has the right to acquire from the Company
the Shares (as defined in the Warrant).

         B. By this Antidilution Agreement, the Purchaser and the Company desire
to set forth the adjustment in the number of Shares issuable upon exercise of
the Warrant as a result of a Diluting Issuance (as defined below).

         C. Capitalized terms used herein shall have the same meaning as set
forth in the Warrant.

         NOW, THEREFORE, in consideration of the mutual promises, covenants and
conditions hereinafter set forth, the parties hereto mutually agree as follows:

                  1. Definitions. As used in this Antidilution Agreement, the
following terms have the following respective meanings:

         (a) "Option" means any right, option or warrant to subscribe for,
purchase or otherwise acquire common stock or Convertible Securities.

         (b) "Convertible Securities" means any evidences of indebtedness,
shares of stock or other securities directly or indirectly convertible into or
exchangeable for common stock.

         (c) "Issue" means to grant, issue, sell, assume or fix a record date
for determining persons entitled to receive any security (including Options),
whichever of the foregoing is the first to occur.

         (d) "Additional Common Shares" means all common stock (including
reissued shares) Issued (or deemed to be issued pursuant to Section 2) after the
date of the Warrant. Additional Common Shares does not include, however, any
common stock Issued in a transaction described in Sections 2.1 and 2.2 of the
Warrant; any common stock Issued upon conversion or exercise of any convertible
securities Issued prior to the date of this Agreement; any common stock Issued
upon conversion of preferred stock outstanding on the date of the Warrant; the
Shares; or common stock Issued as incentive or in a nonfinancing transaction to
employees, officers, directors of or consultants to the Company.


                                       10
<PAGE>   11
         (e) The shares of common stock ultimately issuable upon exercise of an
Option (including the shares of common stock ultimately Issuable upon conversion
or exercise of a Convertible Security Issuable pursuant to an Option) are deemed
to be Issued when the Option is Issued. The shares of common stock ultimately
Issuable upon conversion or exercise of a Convertible Security (other than a
Convertible Security Issued pursuant to an Option) shall be deemed Issued upon
Issuance of the Convertible Security.

                  2. Deemed Issuance of Additional Common Shares. The shares of
common stock ultimately Issuable upon exercise of an Option (including the
shares of common stock ultimately Issuable upon conversion or exercise of a
Convertible Security Issuable pursuant to an Option) are deemed to be Issued
when the Option is Issued. The shares of common stock ultimately Issuable upon
conversion or exercise of a Convertible Security (other than a Convertible
Security Issued pursuant to an Option) shall be deemed Issued upon Issuance of
the Convertible Security. The maximum amount of common stock Issuable is
determined without regard to any future adjustments permitted under the
instrument creating the Options or Convertible Securities.

                  3. Adjustment of Warrant Price for Diluting Issuances.

                  3.1 Weighted Average Adjustment. If the Company issues
Additional Common Shares after the date of the Warrant and the consideration per
Additional Common Share (determined pursuant to Section 9) is less than the
Warrant Price in effect immediately before such Issue (a "Diluting Issuance"),
the Warrant Price in effect immediately before such Issue shall be reduced,
concurrently with such Issue, to a price (calculated to the nearest hundredth of
a cent) determined by multiplying the Warrant Price by a fraction:

                  (a) the numerator of which is the amount of common stock
outstanding immediately before such Issue plus the amount of common stock that
the aggregate consideration received by Company for the Additional Common Shares
would purchase at the Warrant Price in effect immediately before such Issue, and

                  (b) the denominator of which is the amount of common stock
outstanding immediately before such Issue plus the number of such Additional
Shares.

                  3.2 Adjustment of Number of Shares. Upon each adjustment of
the Warrant Price, the number of Shares Issuable upon exercise of the Warrant
shall be increased to equal the quotient obtained by dividing (a) the product
resulting from multiplying (i) the number of Shares Issuable upon exercise of
the Warrant and (ii) the Warrant Price, in each case as in effect immediately
before such adjustment, by (b) the adjusted Warrant Price.

                  3.3 Securities Deemed Outstanding. For the purpose of this
Section 3, all securities Issuable upon exercise of any outstanding Convertible
Securities or Options, Warrants, or other rights to acquire securities of the
Company shall be deemed to be outstanding.

                  4. No Adjustment for Issuances Following Deemed Issuances. No
adjustment to the Warrant Price shall be made upon the exercise of Options or
conversion of Convertible Securities.


                                       11
<PAGE>   12
                  5. Adjustment Following Changes in Terms of Options or
Convertible Securities. If the consideration payable to, or the amount of common
stock Issuable by, the Company increases or decreases, respectively, pursuant to
the terms of any outstanding Options or Convertible Securities, the Warrant
Price shall be recomputed to reflect such increase or decrease. The
recomputation shall be made as of the time of the Issuance of the Options or
Convertible Securities. Any changes in the Warrant Price that occurred after
such Issuance because other Additional Common Shares were Issued or deemed
Issued shall also be recomputed. The foregoing notwithstanding, this Section 5
shall not apply to the terms of the Series A 8% Participating Preferred Stock
existing on the date hereof.

                  6. Recomputation Upon Expiration of Options or Convertible
Securities. The Warrant Price computed upon the original Issue of any Options or
Convertible Securities, and any subsequent adjustments based thereon, shall be
recomputed when any Options or rights of conversion under Convertible Securities
expire without having been exercised. In the case of Convertible Securities or
Options for common stock, the Warrant Price shall be recomputed as if the only
Additional Common Shares Issued were the shares of common stock actually Issued
upon the exercise of such securities, if any, and as if the only consideration
received therefor was the consideration actually received upon the Issue,
exercise or conversion of the Options or Convertible Securities. In the case of
Options for Convertible Securities, the Warrant Price shall be recomputed as if
the only Convertible Securities Issued were the Convertible Securities actually
Issued upon the exercise thereof, if any, and as if the only consideration
received therefor was the consideration actually received by the Company
(determined pursuant to Section 9), if any, upon the Issue of the Options for
the Convertible Securities.

                  7. Limit on Readjustments. No readjustment of the Warrant
Price pursuant to Sections 5 or 6 shall increase the Warrant Price more than the
amount of any decrease made in respect of the Issue of any Options or
Convertible Securities.

                  8. 30 Day Options. In the case of any Options that expire by
their terms not more than 30 days after the date of Issue thereof, no adjustment
of the Warrant Price shall be made until the exercise of all such Options.

                  9. Computation of Consideration. The consideration received by
the Company for the Issue of any Additional Common Shares shall be computed as
follows:

         (a) Cash. Cash shall be valued at the amount of cash received by the
Corporation, excluding amounts paid or payable for accrued interest or accrued
dividends.

         (b) Property. Property, other than cash, shall be computed at the fair
market value thereof at the time of the Issue as determined in good faith by the
Board of Directors of the Company.

         (c) Mixed Consideration. The consideration for Additional Common Shares
Issued together with other property of the Company for consideration that covers
both shall be determined in good faith by the Board of Directors.

         (d) Options and Convertible Securities. The consideration per
Additional Common Share for Options and Convertible Securities shall be
determined by dividing:


                                       12
<PAGE>   13
                  (i) the total amount, if any, received or receivable by the
Company for the Issue of the Options or Convertible Securities, plus the minimum
amount of additional consideration (as set forth in the instruments relating
thereto, without regard to any provision contained therein for a subsequent
adjustment of such consideration) payable to the Company upon exercise of the
Options or conversion of the Convertible Securities, by

                  (ii) the maximum amount of common stock (as set forth in the
instruments relating thereto, without regard to any provision contained therein
for a subsequent adjustment of such number) ultimately Issuable upon the
exercise of such Options or the conversion of such Convertible Securities.

                  10. General.

                  10.1 Governing Law. This Antidilution Agreement shall be
governed in all respects by the laws of the State of California as such laws are
applied to agreements between California residents entered into and to be
performed entirely within California.

                  10.2 Successors and Assigns. Except as otherwise expressly
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.

                  10.3 Entire Agreement. Except as set forth below, this
Antidilution Agreement and the other documents delivered pursuant hereto
constitute the full and entire understanding and agreement between the parties
with regard to the subjects hereof and thereof.

                  10.4 Notices, etc. All notices and other communications
required or permitted hereunder shall be in writing and shall be mailed by first
class mail, postage prepaid, certified or registered mail, return receipt
requested, addressed (a) if to Purchaser at Purchaser's address as set forth
below, or at such other address as Purchaser shall have furnished to the Company
in writing, or (b) if to the Company, at the Company's address set forth below,
or at such other address as the Company shall have furnished to the Purchaser in
writing.

                  10.5 Severability. In case any provision of this Antidilution
Agreement shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions of this Antidilution Agreement shall
not in any way be affected or impaired thereby.

                  10.6 Titles and Subtitles. The titles of the sections and
subsections of this Agreement are for convenience of reference only and are not
to be considered in construing this Antidilution Agreement.

                  10.7 Counterparts. This Antidilution Agreement may be executed
in any number of counterparts, each of which shall be an original, but all of
which together shall constitute one instrument.


                                       13
<PAGE>   14
PURCHASER                               ISSUER

IMPERIAL BANCORP                        ALLIANCE MEDICAL CORPORATION

By:                                     By:
    ---------------------------             ---------------------------

Name:                                   Name:

Title:                                  Title:

Address:                                Address:




                                       14
<PAGE>   15
                                    EXHIBIT C

                               Registration Rights

         The Shares shall be deemed "registrable securities" or otherwise
entitled to "piggy back" registration rights in accordance with the terms of the
following agreement (the "Agreement") between the Company and its investor(s):

         Registration Rights Agreement, dated as of April __, 2000, by and
         between Imperial Bank and Alliance Medical Corporation

         The Company agrees that no amendments will be made to the Agreement
which would have an adverse impact on Holder's registration thereunder without
the consent of Holder. By acceptance of the Warrant to which this Exhibit C is
attached, Holder shall not be deemed to be a party to the Agreement, but solely
entitled to the registration rights created thereby.

         If no Agreement exists, then the Company and the Holder shall enter
into Holder's standard form of Registration Rights Agreement as in effect on the
Issue Date of the Warrant.




                                       15