<PAGE>


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                         AMENDMENT NO. 1 TO FORM 10-QSB
(Mark One)

/X/        QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
           SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended
           December 31, 1999

                                       OR

/ /        TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
           EXCHANGE ACT OF 1934

                        COMMISSION FILE NUMBER: 1097181

                                  -------------

                           MOBILE P.E.T. SYSTEMS, INC.
             (Exact name of registrant as specified in its charter)

                DELAWARE                              11-2787966
      (State or other jurisdiction                 (I.R.S. Employer
            of organization)                      Identification No.)

                         2240 SHELTER ISLAND DRIVE #205
                               SAN DIEGO, CA 92106
                    (Address of principal executive offices)

                                 (619) 226-6738
                (Issuer's telephone number, including area code)

                                 NOT APPLICABLE
      (Former name, address and fiscal year, if changed since last report)

         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.

                        YES / /                    NO /X/

         As of December 31, 1999, 13,359,658 shares of the registrant's common
stock were outstanding.


<PAGE>


                         PART I - FINANCIAL INFORMATION

Item 1.  Financial Statements  (unaudited)

         The following financial statements are furnished:

         Consolidated Balance sheet as of December 31, 1999

         Consolidated Statements of Operations for the three months and six
         months ended December 31, 1999

         Consolidated Statement of Cash Flows for the three months and six
         months ended December 31, 1999

         Consolidated Statement of Shareholders' Equity (Deficit) as of December
         31, 1999

         Notes to Unaudited Consolidated Financial Statements


                                        2
<PAGE>


                  MOBILE P.E.T. SYSTEMS, INC. AND SUBSIDIARIES
                           CONSOLIDATED BALANCE SHEET
                                   (UNAUDITED)

<TABLE>
<CAPTION>

                                                                                 December 31, 1999
                                                                                 -----------------
<S>                                                                              <C>
                                   ASSETS
CURRENT ASSETS
     Cash                                                                          $   338,094
     Due from London Radiosurgical Center, Ltd.                                        256,024
     Accounts receivable                                                               246,225
     Prepaid expenses                                                                   97,750
     Deposits and other assets                                                         487,931
                                                                                   -----------

         Total current assets                                                        1,426,024

PROPERTY AND EQUIPMENT, NET                                                            292,526

OTHER ASSETS
     Subordinated equity participation                                                 200,000
     Restricted cash                                                                   105,226
                                                                                   -----------

         Total assets                                                              $ 2,023,776
                                                                                   ===========



                    LIABILITIES AND SHAREHOLDERS' EQUITY

CURRENT LIABILITIES
     Accounts payable                                                              $   225,330
     Income taxes payable                                                                  800
     Accrued liabilities                                                               171,651
     Notes payable                                                                     106,834
                                                                                   -----------

         Total current liabilities                                                     504,615

OTHER LIABILITIES
     Deferred revenues                                                                  72,505
                                                                                   -----------

         Total liabilities                                                             577,120

SHAREHOLDERS' EQUITY
     Common stock $0.0001 par value; 20,000,000 shares authorized,
         13,359,658 shares issued and outstanding December 31, 1999                      1,336
     Additional paid in capital                                                      4,742,947
     Accumulated deficit                                                            (3,294,177)
     Foreign currency translation adjustment                                            (3,450)
                                                                                   -----------

         Total shareholders' equity                                                  1,446,656
                                                                                   -----------

         Total liabilities and shareholders' equity                                $ 2,023,776
                                                                                   ===========

</TABLE>


            See notes to unaudited consolidated financial statements.


                                        3
<PAGE>


                  MOBILE P.E.T. SYSTEMS, INC. AND SUBSIDIARIES
                      CONSOLIDATED STATEMENTS OF OPERATIONS
                                   (UNAUDITED)

<TABLE>
<CAPTION>

                                                                  Three Months Ended      Six Months Ended
                                                                  December 31, 1999       December 31, 1999
                                                                  ------------------      -----------------
<S>                                                               <C>                     <C>
Revenues                                                              $   216,925         $   296,920
Cost of service revenues                                                   69,828             126,877
                                                                  ------------------      -----------------
     Gross profit                                                         147,097             170,043

Expenses
     General and administrative                                           910,005           1,621,786
                                                                  ------------------      -----------------
                                                                          910,005           1,621,786
                                                                  ------------------      -----------------
         Loss from operations                                            (762,908)         (1,451,743)

Other income (expenses)
     Interest income                                                        2,663               9,329
     Interest expense                                                     (11,760)            (26,299)
                                                                  ------------------      -----------------
         Total other income (expense)                                      (9,097)            (16,970)
                                                                  ------------------      -----------------


     Loss before provision for income taxes                              (772,805)         (1,468,713)
     Provision for income taxes                                               800               1,600
                                                                  ------------------      -----------------
         Net loss                                                     $  (772,805)        $(1,470,313)
                                                                  ==================      =================

Basis loss per share                                                  $     (0.06)        $     (0.11)
Diluted loss per share                                                $     (0.06)        $     (0.11)

</TABLE>


            See notes to unaudited consolidated financial statements.


                                        4
<PAGE>


                  MOBILE P.E.T. SYSTEMS, INC. AND SUBSIDIARIES
                      CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (UNAUDITED)

<TABLE>
<CAPTION>

                                                                           Three Months Ended          Six Months Ended
                                                                           December 31, 1999           December 31, 1999
                                                                           ------------------          -----------------
<S>                                                                        <C>                         <C>
Cash flows from operating activities
      Net loss                                                                  $(772,805)                 $(1,470,313)
      Adjustments to reconcile net loss to net cash used in
         operating activities
         Depreciation                                                              57,470                       95,516
         (Increase) decrease in restricted cash                                    (1,186)                     147,146
         Increase in note from London Radiosurgical Center, Ltd.                  (44,006)                    (226,053)
         Increase in accounts receivables                                        (108,110)                    (246,225)
         Increase in prepaid expenses                                             (76,198)                     (79,759)
         Increase in deposits and other assets                                     98,910                       64,000
         Increase in accounts payable                                             170,515                      143,462
         Increase in accrued interest                                               6,172                       14,672
         Increase in accrued liabilities                                           55,776                       68,228
         Increase in deferred revenue                                              72,505                       72,505
                                                                           ------------------          -----------------
                  Net cash used in operating activities                          (540,957)                  (1,416,821)
Cash Flows from investing activities
      Purchase of fixed assets                                                   (312,266)                  (1,247,703)
      Proceeds from sale of fixed assets                                        1,551,890                    1,551,890
                                                                           ------------------          -----------------
         Net cash used in investing activities                                  1,239,624                      304,187
Cash flows from financing activities
      Proceeds from loan                                                          106,834                      106,834
      Payments on loan                                                           (637,500)                    (637,500)
      Common stock issued                                                              --                      197,000
                                                                           ------------------          -----------------
         Net cash provided by financing activities                               (530,666)                    (333,666)
                                                                           ------------------          -----------------
      Effect of exchange rate changes on cash                                           4                            4
         Net increase (decrease) in cash                                          168,005                   (1,446,296)
      Cash - beginning of period                                                  170,089                    1,784,390
                                                                           ------------------          -----------------
      Cash - end of period                                                      $ 338,094                  $   338,094
                                                                           ==================          =================
Supplement Disclosures
      Interest paid                                                             $  11,760                  $    26,299
      Income taxes paid                                                         $     800                  $     1,600

</TABLE>


            See notes to unaudited consolidated financial statements


                                        5
<PAGE>


                  MOBILE P.E.T. SYSTEMS, INC. AND SUBSIDIARIES
            CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (DEFICIT)
                                   (UNAUDITED)

<TABLE>
<CAPTION>

                                                                                                     Foreign
                                                                        Additional                  Currency         Total
                                                                         Paid In     Accumulated   Translation    Shareholders'
                                                   Shares      Amount    Capital       Deficit      Adjustment       Equity
                                                 ----------    ------   ----------   -----------   -----------    ------------
<S>                                              <C>           <C>     <C>           <C>           <C>            <C>
Balance - June 30, 1999                          12,844,658    $1,285  $4,545,998    $(1,823,864)   $   --          $2,723,419

Common stock issued in private placement,
         net of offering                            515,000        51     196,949                       --             197,000

Net loss - July 1, 1999 to September 30, 1999                                           (697,508)       --            (697,508)
                                                 ----------    ------  ----------    -----------   -----------      ----------

      Balance - September 30, 1999               13,359,658     1,336   4,742,947     (2,521,372)       --           2,222,911
                                                 ----------    ------  ----------    -----------   -----------      ----------

Net loss - October 1, 1999 to December 31, 1999                                         (772,805)       --            (772,805)
Foreign currency translation adjustment                                                              (3,450)            (3,450)
                                                 ----------    ------  ----------    -----------   -----------      ----------

      Balance - December 31, 1999                13,359,658    $1,336  $4,742,947    $(3,294,177)   $(3,450)        $1,446,656
                                                 ==========    ======  ==========    ===========   ===========      ==========

</TABLE>


            See notes to unaudited consolidated financial statements.


                                        6
<PAGE>


                           MOBILE P.E.T. SYSTEMS, INC.
              NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS


1.       THE COMPANY

         Mobile PET Systems, Inc. was incorporated in the State of Nevada on
December 1, 1998. On December 22, 1998, the Company's shareholders exchanged
all of their shares of common stock for shares of common stock in Colony
International Incorporated, prior to that named American Coin and Stamp
Ventures Inc., incorporated in the State of Delaware on August 21, 1985 and
its wholly-owned subsidiary Colony International Incorporated, incorporated
in the State of Nevada on April 25, 1995. Mobile PET Systems, Inc. was merged
into Colony International Incorporated on December 22, 1998 and Colony
International Incorporated changed its name to Mobile PET Systems, Inc. (the
"Company"), the surviving corporation. On December 10, 1999, The London PET
Centre Ltd. and Mobile PET Leasing Ltd. were incorporated as wholly owned
foreign subsidiaries of the Company.

2.       BASIS OF PRESENTATION

         The consolidated financial statements included herein have been
prepared without audit pursuant to the rules and regulations of the
Securities and Exchange Commission ("SEC" or "Commission"). The consolidated
financial statements include the accounts of the Company and its subsidiaries
as mentioned in note 1. Certain information and footnote disclosures normally
included in financial statements prepared in accordance with generally
accepted accounting principles have been condensed or omitted pursuant to
such rules and regulations. The accompanying financial statements reflect all
adjustments that are, in the opinion of management, necessary to a fair
statement of the results for the interim periods presented. Such adjustments
are of a normal recurring nature.

         Assets and liabilities of foreign subsidiaries are translated at
current exchange rates with the related translation adjustments reported as a
separate component of stockholders' equity.  Income statement accounts are
translated at the average exchange rate during the period.  Non-monetary
assets and liabilities are translated at historical exchange rates.

         The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities, the
disclosure of contingent assets and liabilities, and the reported amounts of
revenues and expenses during the period. Actual results could differ from those
estimates.

         The consolidated financial statements should be read in conjunction
with the audited financial statements and the notes thereto included in the
registrant's amended Form-10B for the year ended June 30, 1999. The results for
the three months ended December 31, 1999 and the six months ended December 31,
1999 are not necessarily indicative of the results that may be expected for the
year ended June 30, 2000.

3.       CERTAIN TRANSACTIONS

         In July 1999, the Company purchased a second mobile PET system for
$1,556,890 with cash in the amount of $919,390 and a note in the amount of
$637,500. In December 1999, the Company completed a sale/leaseback
transaction on the mobile PET system for $1,537,025 with a leasing company.
In the sale/leaseback transaction, the Company received cash of $899,525;
repaid the note; and entered into a five-year lease for the equipment.

         On December 10, 1999, the Company converted working capital advances
into 100% of the capital stock of a newly formed limited company named The
London PET Centre, Ltd.  Also on December 10, 1999, the Company formed Mobile
PET Leasing Ltd., a 100% owned subsidiary of the Company.  Foreign currency
translation adjustments of $(3,450) attributable to these activities have
been reported as a separate component of shareholders' equity.

4.       NOTES PAYABLE

         The Company entered into an oral agreement for a bridge loan in the
amount of $50,000 from Northwest Capital Partners, LLC, related through a
common shareholder and board membership.  The loan is non-interest bearing
and is payable not later than six months from the date of the agreement,
December 20, 1999.  The Company entered into an insurance premium finance
agreement with AFCO Acceptance Corp. in the amount of $56,834, bearing
interest of 9.002%, payable in 8 monthly installments commencing February 9,
2000.

5.       SHAREHOLDERS' EQUITY

         In July 1999, the Company issued 515,000 shares of common stock,
completing a private placement. The Company received cash in the amount of
$1,572,000, net of offering costs prior to July 1, 1999, and an additional
$300,000 in July 1999 for a total of $1,872,000. In connection with the
placement, the Company issued to the investors 51,500 warrants to purchase
shares of common stock at an exercise price of $4.00 per share. The warrants
expire on June 30, 2002.

         During the period July 1, 1999 to October 8, 1999, the Company issued
options to purchase 609,000 shares of common stock at an exercise price of the
average price per share of the Company's common stock during the calendar year
1999 which was between $1.00 to $4.00 per share. These stock options expire
between June 30, 2002 and 2005 and vest over periods ranging from zero to four
years.

6.       RELATED PARTIES

         DUE FROM LONDON RADIOSURGICAL CENTRE LTD ("LRC")

         During the period July 1, 1999 to December 31, 1999, the Company
advanced without interest, $226,053 to LRC. At December 31, 1999, the balance
due from LRC was $256,024.

         SUBORDINATED EQUITY PARTICIPATION

         The Company carries an 8% interest in a subordinated equity
participation in London Radiosurgical Centre Ltd. (LRC), a foreign
corporation with a common shareholder, officer and director. The subordinated
equity participation is recorded at cost in the amount of $200,000. The
agreement provides first for a distribution of cash to investors, if any, up
to the amount of their investments, after which distribution of 60% of net
income. According to the terms of the participation agreement, net income for
distribution is equal to net income less equipment financing payments,
operating expenses, reserve capital and taxes.

7.       COMMITMENTS

         In December 1999, the Company guaranteed a 6 year lease of Mobile
P.E.T. Leasing Ltd. (a newly formed wholly-owned subsidiary of the Company)
with IGE Medical Systems for 1.1 Million Pounds($1.7 million) for a GE Advance
PET System.

8.       SUBSEQUENT EVENTS


                                        7
<PAGE>


         In January 2000, the Company conducted a private placement to
accredited investors of 550,000 shares of common stock at $1.75 per share,
the proceeds from which was $962,458.

         Pursuant to an action by written consent of the majority of the
shareholders of the Company, effective January 28, 2000, the Company amended
and restated its Certificate of Incorporation to increase the number of
authorized shares from 20,000,000 shares to 100,000,000 shares, of which
90,000,000 shares are designated as common stock and 10,000,000 shares are
designated as preferred stock. The shares of preferred stock may be issued by
the Company's board of directors in such series and with such rights,
privileges and preferences as they may determine.

         In March 2000, the Company completed a private placement of 60
shares of Series A Convertible Preferred Stock to York, LLC, raising proceeds
of $3,000,000.  Concurrently with this private placement, the Company filed a
Certificate of Designation to its Certificate of Incorporation setting forth
the rights, privileges, preferences and other terms of the Series A
Convertible Preferred Stock.

ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
         OF OPERATIONS

OVERVIEW

         For the period from our inception through September 30, 1999, we had
minimal revenues and our operating activities related primarily to
establishing the management and operating infrastructure to provide PET
systems and services to hospitals and other health care providers on a
mobile, shared user basis. During the six-month period ended December 31,
1999, we commenced accruing revenues from the first PET unit placed in
operation in July of 1999. We placed a second unit into operation in December
1999.

         Since forming the Company, operating activities have been focused on
establishing a national sales force, creating and executing a sales and
marketing strategy directed to key potential hospital and health care providers;
securing a $10 million lease financing package; establishing key equipment
vendor relationships; promoting our service brand strategy; and building a
management and operations infrastructure to effectively and efficiently manage
future operating growth opportunities.

         Our PET services include the provision of high technology imaging
systems, technologists to operate the imaging systems, the management of
day-to-day operations and educational and marketing support. Our services
enable leading as well as small to mid-size hospitals to gain access to
advanced diagnostic imaging technology and related value-added services
without making a substantial investment in equipment and personal.

         Our future revenues will principally be a function of the number of
mobile units in service, scan volumes and fees per scan. We generate
substantially all of our revenues from exclusive five-year contracts with
hospitals and health care providers. Our contracts offer tiered pricing which
may include lower fees per scan on incremental scans, allowing hospitals and
other health care customers to benefit from increased scan volumes and
provide us with the opportunity to benefit from operating leverage that may
be associated with increased scan volumes.

         The principal component of our operating costs include salaries paid to
technologists and drivers, annual system maintenance costs, insurance and
transportation costs.

         Since inception, we have incurred significant losses and, as of
December 31, 1999, had incurred cumulative net losses of $3,294,177. We
expect to experience operating losses and negative cash flow for the
foreseeable future. We anticipate our losses will increase significantly from
current levels as we expect to incur additional costs and expenses related to
staffing, infrastructure development, marketing and sales activities and
other capital expenditures. As a result, we will need to generate significant
revenues to achieve and maintain profitability.

         We have a limited operating history on which to base an evaluation of
our business and prospects. You must consider our prospects in light of the
risks, expenses and difficulties frequently encountered by companies in their
early stage of development. To address these risks, we must establish, maintain
and expand our customer base, implement and successfully execute our business
and marketing strategy, provide superior customer service, anticipate and
respond to competitive developments and attract, retain and motivate qualified
personnel. We cannot assure you that we will be successful in addressing these
risks, and our failure to do so could have a negative impact on our business,
operating results and financial condition.


                                        8
<PAGE>


RESULTS OF OPERATIONS

         FOR THE THREE MONTHS ENDED DECEMBER 31, 1999

         The net loss totaled $772,805 or $ .06 per share for the three months
ended December 31, 1999.

         The revenues totaled $216,925 for the three months ended December
31, 1999. The majority of our service revenues were generated from our first
unit placed into service in our first quarter of 1999. Our second unit was
placed in operation in late December and accrued minimum revenues.

         The costs of service revenues represent salaries paid to technologists
and drivers, annual system maintenance costs, insurance, transportation costs
and the lease payment on our mobile PET system. In the three months ended
December 31, 1999, cost of service revenues totaled $69,828 or 32.2% of
revenues. In the three months ended December 31, 1999, we hired additional
technologists and drivers in anticipation of future mobile PET route growth.

         General and administrative expenses for the three months ended December
31, 1999 totaled $910,005.

         FOR THE SIX MONTHS ENDED DECEMBER 31, 1999

         The net loss totaled $1,470,313 or $ .11 per share for the six months
ended December 31, 1999.

         Our service revenues totaled $296,920 for the six months ended December
31, 1999. The majority of our service revenues were generated in the six month
period reflecting the initial operation of two mobile PET systems.

         The costs of service revenues represent salaries paid to technologists
and drivers, annual system maintenance costs, insurance, transportation costs
and the lease payment on our mobile PET system. Cost of service revenues for the
six months ended December 31, 1999 was $126,877 or 42.7% of total service
revenues.

         General and administrative expenses for the six months ended December
31, 1999 totaled $1,621,786. In the six month period ended December 31, 1999, we
incurred increased general and administrative expenses due primarily to the
growth in staff and related expenses incurred in building our infrastructure,
and increase advertising and marketing costs related to the introduction of our
mobile PET services.

LIQUIDITY AND CAPITAL RESOURCES

         At December 31, 1999, our total assets were $2,023,776, compared to
$2,894,837 at June 30, 1999. Current assets at December 31, 1999 totaled
$1,426,024 and current liabilities were $504,615. Stockholders' equity at
December 31, 1999 decreased to $1,446,656 from $2,723,419 at June 30, 1999,
due primarily to the net loss of $1,470,313 incurred in the six month period
ended December 31, 1999. We issued common stock in the six month period ended
December 31, 1999 that totaled $197,000.

         In July 1999, we purchased our second mobile PET system for
$1,556,890 with cash of $919,390 and the issuance of a note in the amount of
$637,500. In December 1999, we completed a sale/leaseback transaction on this
mobile PET system for $1,537,025 with a leasing company. In the
sale/leaseback transaction, the Company received cash of $899,525; repaid the
note; and entered into a five-year lease for the equipment. At the date of the
sale/leaseback transaction, the net book value was $1,459,520.

         Net cash used by financing activities for the six months ended
December 31, 1999 was $333,666, resulting principally from the repayment of
the $637,500 note mentioned above, the issuance of common stock for cash in
the amount of $197,000 and the proceeds from a $50,000 bridge loan and a
$56,834 insurance premium finance agreement.

         We have experienced a substantial increase in our capital expenditures
since our inception, consistent with our growth in operations and staffing, and
we anticipate that this will continue for the foreseeable future. Additionally,
we continue to evaluate possible expenditures and investments in businesses,
geographic service expansion and service offerings. We cannot be certain that
the underlying assumed levels of revenues and expenses will prove to be
accurate.


                                        9
<PAGE>

PART II. OTHER INFORMATION

ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K

        (a) Exhibit 10

            Sale/Leaseback Contracts
            Securities Purchase Agreement

            Exhibit 27.

            Financial Data Schedule

        (b) Reports on Form 8-K

            None


                                       10
<PAGE>


                                    SIGNATURE



         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 thereunto duly authorized.


                                 MOBILE P.E.T. SYSTEMS, INC.


Date: March 16, 2000              By: /s/ Thomas G. Brown
                                    --------------------------------------------
                                    Thomas G. Brown, Chief Financial Officer




                                       11