<PAGE>   1

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                    FORM 10-Q
       QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
                              EXCHANGE ACT OF 1934


(MARK ONE)

[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934

     FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30, 1999

[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ______________________

                           COMMISSION FILE NO. 0-23311


                                RADIOLOGIX, INC.
             (Exact name of registrant as specified in its charter)


          DELAWARE                                       75-2648089
(State or other jurisdiction                          (I.R.S. Employer
     of incorporation or                               Identification)
       organization)


                                2200 ROSS AVENUE
                                3600 CHASE TOWER
                               DALLAS, TEXAS 75201
          (Address of principal executive offices, including zip code)

                                 (214) 303-2776
              (Registrant's telephone number, including area code)

                        AMERICAN PHYSICIAN PARTNERS, INC.
                   (Former name, 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 [X] No [ ]

         Indicate the number of shares outstanding of each of the issuer's
classes of common stock, as of the latest practicable date.

                Class                          Outstanding at November 15, 1999
                -----                          --------------------------------
     COMMON STOCK, $0.0001 PAR VALUE                  19,312,213  SHARES

================================================================================
<PAGE>   2


                                RADIOLOGIX, INC.

                                    FORM 10-Q

                                      INDEX

<TABLE>
<CAPTION>
FORM 10-Q ITEM                                                                                                      PAGE
                                                                                                                    ----
<S>      <C>      <C>
PART I.  FINANCIAL INFORMATION

         Item 1.  Financial Statements

                  Consolidated Balance Sheets as of September 30, 1999 (Unaudited) and December 31, 1998............  1

                  Consolidated Statements of Income (Unaudited) for the three months and nine months
                  ended September 30, 1999 and 1998.................................................................  2

                  Consolidated Statements of Cash Flows (Unaudited) for the three months and nine months
                  ended September 30, 1999 and 1998.................................................................  3

                  Notes to Consolidated Financial Statements........................................................  4

         Item 2.  Management's Discussion and Analysis of Financial Condition and Results of Operations.............  8

         Item 3.  Quantitative and Qualitative Disclosures About Market Risk ....................................... 14

PART II.  OTHER INFORMATION

         Item 1.  Legal Proceedings................................................................................. 15

         Item 2.  Changes in Securities and Use of Proceeds......................................................... 15

         Item 3.  Defaults Upon Senior Securities................................................................... 15

         Item 4.  Submission of Matters to a Vote of Security Holders............................................... 15

         Item 5.  Other Information ................................................................................ 15

         Item 6.  Exhibits and Reports on Form 8-K.................................................................. 15

SIGNATURES.......................................................................................................... 16
</TABLE>

<PAGE>   3
                        RADIOLOGIX, INC. AND SUBSIDIARIES

                           CONSOLIDATED BALANCE SHEETS
                                 (IN THOUSANDS)

                                     ASSETS

<TABLE>
<CAPTION>
                                                                                SEPTEMBER 30,    DECEMBER 31,
                                                                                   1999              1998
                                                                                -----------      -----------
                                                                                (UNAUDITED)
<S>                                                                             <C>              <C>
CURRENT ASSETS:
   Cash and cash equivalents ................................................... $     7,352      $     6,485
   Accounts receivable, net of allowances ......................................      59,969           36,789
   Due from affiliated practices ...............................................       2,586            1,412
   Other current assets ........................................................       3,413            2,835
                                                                                 -----------      -----------
      Total current assets .....................................................      73,320           47,521
PROPERTY AND EQUIPMENT, net of accumulated depreciation ........................      65,417           37,002
INVESTMENTS IN JOINT VENTURES ..................................................       6,407            5,424
INTANGIBLE ASSETS, net .........................................................      86,989           61,119
DEFERRED FINANCING COSTS, net ..................................................       4,137            3,408
OTHER ASSETS ...................................................................       1,284            2,165
                                                                                 -----------      -----------
      Total assets ............................................................. $   237,554      $   156,639
                                                                                 ===========      ===========

                                    LIABILITIES AND STOCKHOLDERS' EQUITY

CURRENT LIABILITIES:
   Accounts payable and accrued expenses ....................................... $    14,210      $    13,884
   Accrued physician retention .................................................       7,884            6,319
   Accrued salaries and benefits ...............................................       5,314            3,893
   Current portion of long-term debt ...........................................       1,221              840
   Current portion of capital lease obligations ................................       1,654            1,677
   Deferred income taxes .......................................................         617              636
   Other current liabilities ...................................................          17              894
                                                                                 -----------      -----------
      Total current liabilities ................................................      30,917           28,143
DEFERRED INCOME TAXES ..........................................................       3,077            2,406
LONG-TERM DEBT, net of current portion .........................................     143,209          113,807
CONVERTIBLE NOTES ..............................................................      20,000               --
CAPITAL LEASE OBLIGATIONS, net of current portion ..............................      19,683            3,887
OTHER LIABILITIES ..............................................................         153              243
                                                                                 -----------      -----------
      Total liabilities ........................................................     217,039          148,486

MINORITY INTERESTS IN CONSOLIDATED SUBSIDIARIES ................................       1,155            1,107

STOCKHOLDERS' EQUITY:
   Common stock ................................................................           2                2
   Additional paid-in capital ..................................................        (603)            (910)
   Retained earnings ...........................................................      19,961            7,954
                                                                                 -----------      -----------
      Total stockholders' equity ...............................................      19,360            7,046
                                                                                 -----------      -----------
      Total liabilities and stockholders' equity ............................... $   237,554      $   156,639
                                                                                 ===========      ===========
</TABLE>


See accompanying notes to unaudited condensed consolidated financial statements.

                                        1

<PAGE>   4
                        RADIOLOGIX, INC. AND SUBSIDIARIES

                        CONSOLIDATED STATEMENTS OF INCOME
                      (IN THOUSANDS, EXCEPT PER SHARE DATA)

<TABLE>
<CAPTION>
                                                  FOR THE THREE MONTHS          FOR THE NINE MONTHS
                                                  ENDED SEPTEMBER 30,           ENDED SEPTEMBER 30,
                                                  1999           1998           1999           1998
                                                ---------      ---------      ---------      ---------
                                                                      (UNAUDITED)
<S>                                             <C>            <C>            <C>            <C>
SERVICE  FEE REVENUE .......................    $  47,246      $  35,055      $ 129,192      $  98,327

COSTS AND EXPENSES:
  Field salaries and benefits ..............       13,505         10,738         38,128         30,447
  Field supplies ...........................        3,002          2,234          8,321          6,391
  Field rent and lease expenses ............        5,311          2,677         12,872          8,205
  Other field expenses .....................        8,375          7,220         22,693         18,624
  Corporate general and administrative .....        2,910          2,595          8,203          7,034
  Depreciation and amortization ............        5,093          2,976         12,949          8,355
  Interest expense, net ....................        3,383          2,054          8,296          5,142
                                                ---------      ---------      ---------      ---------
     Total costs and expenses ..............       41,579         30,494        111,462         84,198
                                                ---------      ---------      ---------      ---------

INCOME BEFORE TAXES, MINORITY
INTERESTS IN CONSOLIDATED SUBSIDIARIES
AND EQUITY IN EARNINGS OF INVESTMENTS ......        5,667          4,561         17,730         14,129

EQUITY IN EARNINGS OF INVESTMENTS ..........          925          1,096          2,481          2,342

MINORITY INTERESTS IN INCOME OF
CONSOLIDATED SUBSIDIARIES ..................         (237)          (168)          (672)          (391)
                                                ---------      ---------      ---------      ---------

INCOME BEFORE TAXES ........................        6,355          5,489         19,539         16,080

INCOME TAX EXPENSE .........................        2,520          2,081          7,532          6,208
                                                ---------      ---------      ---------      ---------

NET INCOME .................................    $   3,835      $   3,408      $  12,007      $   9,872
                                                =========      =========      =========      =========

NET INCOME PER COMMON SHARE
  Basic ....................................    $    0.20      $    0.18      $    0.62      $    0.53
  Diluted ..................................    $    0.19      $    0.18      $    0.60      $    0.51

WEIGHTED AVERAGE SHARES OUTSTANDING
  Basic ....................................       19,311         18,908         19,301         18,572
  Diluted ..................................       21,246         19,356         20,238         19,219
</TABLE>


See accompanying notes to unaudited condensed consolidated financial statements.

                                       2
<PAGE>   5

                        RADIOLOGIX, INC. AND SUBSIDIARIES

                      CONSOLIDATED STATEMENTS OF CASH FLOWS
                                 (IN THOUSANDS)

<TABLE>
<CAPTION>
                                                                            FOR THE THREE MONTHS        FOR THE NINE MONTHS
                                                                            ENDED SEPTEMBER 30,         ENDED SEPTEMBER 30,
                                                                             1999          1998          1999          1998
                                                                           --------      --------      --------      --------
                                                                                               (UNAUDITED)
<S>                                                                        <C>           <C>           <C>           <C>
     CASH FLOWS FROM OPERATING ACTIVITIES:
        Net income ...................................................     $  3,835      $  3,408      $ 12,007      $  9,872
        Adjustments to reconcile net income to net cash
           provided by (used in) operating activities --
           Minority interests ........................................          237           168           672           391
           Depreciation and amortization .............................        5,093         2,976        12,949         8,355
           Equity in earnings of investments .........................         (925)       (1,096)       (2,481)       (2,342)
           Changes in assets and liabilities- net of acquisitions
               Accounts receivable, net ..............................       (8,617)       (1,769)      (20,257)       (3,776)
               Other current assets ..................................         (928)         (246)       (1,459)        1,810
               Other assets ..........................................       (1,195)         (733)          928        (1,957)
               Accounts payable and accrued expenses .................        2,680           594        (1,146)       (8,139)
               Accrued salaries and benefits .........................         (357)        1,280         1,420         2,322
               Other liabilities .....................................         (342)         (196)         (990)        3,703
                                                                           --------      --------      --------      --------
                  Net cash provided by (used in)
                  operating activities ...............................         (519)        4,386         1,643        10,239
                                                                           --------      --------      --------      --------
     CASH FLOWS FROM INVESTING ACTIVITIES:
        Purchases of property and equipment ..........................       (4,421)       (3,531)      (22,200)       (8,252)
        Cash paid for acquisitions ...................................      (18,051)      (15,924)      (24,641)      (54,905)
        Contributions to joint ventures ..............................         --            --            (115)          352
        Distributions from joint ventures ............................          495           979         1,029         1,062
                                                                           --------      --------      --------      --------
                  Net cash used in investing activities ..............      (21,977)      (18,476)      (45,927)      (61,743)
                                                                           --------      --------      --------      --------
     CASH FLOWS FROM FINANCING ACTIVITIES:
        Proceeds from issuance of long-term debt, net ................        8,116        16,716        27,830        53,988
        Proceeds from issuance of convertible notes ..................       19,400          --          19,400          --
        Payments on capital leases ...................................         (961)         (766)       (2,081)       (1,869)
        Advances to radiology practices, other .......................         --             (20)         --            (237)
        Proceeds from the exercise of options ........................            2            25             2            40
                                                                           --------      --------      --------      --------
                  Net cash provided by financing activities ..........       26,557        15,955        45,151        51,922
                                                                           --------      --------      --------      --------
     NET INCREASE IN CASH
     AND CASH EQUIVALENTS ............................................        4,061         1,865           867           418

     CASH AND CASH EQUIVALENTS, beginning of period ..................        3,291         3,125         6,485         4,572
                                                                           --------      --------      --------      --------

     CASH AND CASH EQUIVALENTS, end of period ........................     $  7,352      $  4,990      $  7,352      $  4,990
                                                                           ========      ========      ========      ========
</TABLE>


See accompanying notes to unaudited condensed consolidated financial statements.

                                       3
<PAGE>   6

                        RADIOLOGIX, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

      The accompanying consolidated unaudited financial statements have been
prepared by Radiologix, Inc., a Delaware corporation (together with its
subsidiaries, "Radiologix" or the "Company"), pursuant to the rules and
regulations of the Securities and Exchange Commission ("SEC"), and reflect all
adjustments (all of which are of a normal recurring nature) which, in the
opinion of management, are necessary for a fair statement of the results of the
interim periods presented. These financial statements do not include all
disclosures associated with the annual financial statements and, accordingly,
should be read in conjunction with the attached Management's Discussion and
Analysis of Financial Condition and Results of Operations and the consolidated
financial statements and notes thereto for the year ended December 31, 1998,
included in Radiologix's Form 10-K/A filed with the SEC on May 12, 1999.

1. DESCRIPTION OF BUSINESS:

      Radiologix develops, consolidates and manages radiology service networks.
These networks consist primarily of free-standing diagnostic imaging centers and
locations at which the Company provides radiology services that have been
outsourced by hospitals. The Company's objective is to develop and operate
networks of radiology facilities to provide a full spectrum of radiology
services and extensive geographic coverage in existing market areas and in
selected new markets. As of November 15, 1999, Radiologix owns, operates or
maintains an ownership interest in imaging equipment at 119 locations and
provides management services to ten radiology practices consisting of 290
physicians who provide professional radiology services at certain of the
Company's radiology centers and at 59 hospitals. Radiologix's radiology networks
and facilities are in geographic markets located in Arizona, California,
Colorado, Florida, Georgia, Illinois, Kansas, Maryland, Minnesota, Missouri,
Nebraska, Nevada, New Jersey, New York, Ohio, Pennsylvania, Texas, the District
of Columbia and Virginia.

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:

Basis of Presentation

      The consolidated financial statements have been prepared on the accrual
basis of accounting and include the accounts of the Company and its
majority-owned subsidiaries. All intercompany accounts and transactions have
been eliminated in consolidation.

Revenue Presentation

      The Financial Accounting Standards Board's Emerging Issues Task Force
issued its abstract, Issue 97-2, "Application of FASB Statement No. 94 and
Accounting Principles Board ("APB") Opinion No. 16 to Physician Practice
Management Entities and Certain Other Entities with Contractual Arrangements"
("EITF 97-2"). In 1998, the Company displayed physician group revenue in its
consolidated statements of income. Since the Company has not established a
"controlling financial interest" under EITF 97-2, the 1998 display has been
restated to reflect the service fees earned as revenues. This change had no
effect on the Company's financial position, results of operations, or liquidity.

      The following table sets forth the amounts of physician groups revenue
that would have been presented in the consolidated statements of income had the
Company met the provisions of EITF 97-2 (in thousands):

<TABLE>
<CAPTION>
                                                          For the Three Months Ended    For the Nine Months Ended
                                                                September 30,                  September 30,
                                                             1999           1998          1999            1998
                                                          ----------     -----------    ----------     ----------
<S>                                                       <C>            <C>            <C>            <C>
      Physician groups revenue, net .................     $  69,252      $  53,869      $ 192,630      $ 152,008
      Less: amounts retained by physician groups ....       (22,006)       (18,814)       (63,438)       (53,681)
                                                          ---------      ---------      ---------      ---------
      Service fee revenue, as reported ..............     $  47,246      $  35,055      $ 129,192      $  98,327
                                                          =========      =========      =========      =========
</TABLE>


                                       4
<PAGE>   7

Service Fee Revenue

      Service fee revenue represents radiology practices revenue less amounts
retained by radiology practices. The amounts retained by radiology practices
represent amounts paid to the radiology practices pursuant to the service
agreements between the Company and the radiology practices. Under the service
agreements, the Company provides each physician group with the facilities and
equipment used in its medical practice, assumes responsibility for the
management of the operations of the practice, and employs substantially all of
the non-physician personnel utilized by the group. Although the Company assists
in negotiating managed care contracts for the radiology practices, it assumes no
risk under these arrangements.

      The Company's service fee revenue is dependent upon the operating results
of the radiology practices. Where state law allows, service fees due under the
service agreements are derived from two distinct revenue streams: (1) a
negotiated percentage (typically 20% to 30%) of the adjusted professional
revenues as defined in the service agreement; and (2) 100% of the adjusted
technical revenues as defined in the service agreements. In states where the law
requires a flat fee structure, the Company has negotiated a base service fee,
which is equal to the fair market value of the services provided under the
service agreement and which is renegotiated each year to equal the fair market
value of the services provided under the service agreement. The fixed fee
structure results in the Company receiving substantially the same amount of
service fee as it would have received under its negotiated percentage fee
structure. Adjusted professional revenues and adjusted technical revenues are
determined by deducting certain contractually agreed-upon expenses
(non-physician salaries and benefits, rent, depreciation, insurance, interest
and other physician costs) from the radiology practices' revenue.

      Service fee revenue consists of the following (in thousands):

<TABLE>
<CAPTION>
                                                         For the Three Months Ended     For the Nine Months Ended
                                                                 September 30,                 September 30,
                                                            1999           1998           1999            1998
                                                         ----------      ----------     ---------      ----------
<S>                                                      <C>             <C>            <C>            <C>
      Professional component ........................     $  11,371      $   8,861      $  30,794      $  25,955
      Technical component ...........................        35,875         26,194         98,398         72,372
                                                          ---------      ---------      ---------      ---------
                                                          $  47,246      $  35,055      $ 129,192      $  98,327
                                                          =========      =========      =========      =========
</TABLE>

3.   ACQUISITIONS:

      On August 1, 1999, the Company acquired all the outstanding stock of
Questar Imaging, Inc. of Tampa, Florida ("Questar"), a private operator of
primarily MRI radiology centers. Questar currently offers magnetic resonance
imaging (MRI) and other diagnostic imaging services at 27 centers in 14 states,
and is in the process of developing 17 additional MRI centers. The total
consideration for the transaction, once completed, will be approximately
$26,825,000 in cash, plus the assumption of certain liabilities. This
transaction will be accounted for using the purchase method.

4.   EARNINGS PER SHARE:

      The Company adopted Statement of Financial Accounting Standards No. 128
("SFAS 128"), "Earnings per Share," effective December 15, 1997. SFAS 128
requires that the calculation of basic earnings per share be calculated by
dividing net income applicable to common stock by the weighted average number of
shares of common stock outstanding during the period and diluted earnings per
common share be calculated using the weighted average number of shares of common
stock and common stock equivalents outstanding during the period. As required,
the Company has reported earnings per share in accordance with SFAS 128.

      The Company has calculated diluted earnings per share based on the
conversion price of the convertible notes (the "Notes") issued on August 3,
1999, as of the date of the financial statements. The Notes have provisions that
require the Company to adjust the conversion price based on certain criteria set
forth in the promissory note. In the event the Company was required to adjust
the conversion price based on these criteria, the diluted earnings per share for
the three months and nine months ended September 30, 1999 would not have
changed. The weighted average shares outstanding used to calculate the diluted
earnings would have been approximately 21,462,000 and 20,310,000 for the three
months and nine months ended September 30, 1999, respectively.


                                       5
<PAGE>   8

5. SEGMENT REPORTING:

      The Company has five reportable segments: Mid-Atlantic Region,
Northeastern Region, Central Region, Western Region and Questar. The Company's
reportable segments are strategic business units defined by management's
division of responsibilities. Each owns and operates imaging centers and (except
for Questar) provides management services to the radiology facilities within
their respective segments.

      The accounting policies of the segments are the same as those described in
the summary of significant accounting policies except that the Company does not
allocate taxes associated with income to any of the regions. They are managed
separately because each segment operates under different contractual
arrangements, providing service to a diverse mix of patients and payors.

                  FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1999
                                 (IN THOUSANDS)

<TABLE>
<CAPTION>
                             Mid-Atlantic  Northeastern   Central       Western
                              Region (1)    Region (2)   Region (3)    Region (4)   Questar(5)     Total
                             ------------  ------------ -----------   -----------  -----------  -----------
<S>                          <C>           <C>          <C>           <C>          <C>          <C>
Service fee revenue          $    54,615   $    39,204  $    14,903   $    17,171  $     3,299  $   129,192
Total operating expenses          34,744        24,900        8,577        11,335        2,458       82,014
                             -----------   -----------  -----------   -----------  -----------  -----------
Segment contribution              19,871        14,304        6,326         5,836          841       47,178
Contribution margin                   36%           36%          42%           34%          25%          37%
Depreciation and
    amortization expense           5,120         2,295          643         1,492          447        9,997
Interest expense                     997           720          159           557          300        2,733
Segment profit                    14,934        11,289        6,170         3,788           75       36,256
Segment assets                    60,282        34,051       17,158        17,322       18,470      147,283
Expenditures for
   segment assets                 11,182         2,021        2,693         3,271           49       19,216
</TABLE>

(1) Includes the Mid-Atlantic Market.
(2) Includes the Finger Lakes and Hudson Valley Markets.
(3) Includes the South Texas, Treasure Coast and Northeast Kansas Markets.
(4) Includes the Bay Area Market.
(5) Includes 27 imaging centers purchased effective August 1, 1999.

                  FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1998
                                 (IN THOUSANDS)

<TABLE>
<CAPTION>
                             Mid-Atlantic  Northeastern   Central       Western
                                Region        Region       Region        Region       Questar       Total
                             ------------  ------------  -----------   -----------  -----------  -----------
<S>                          <C>           <C>           <C>           <C>          <C>          <C>
Service fee revenue          $    43,671   $    28,460   $    12,078   $    14,118  $        --  $    98,327
Total operating expenses          28,339        19,380         6,827         9,121           --       63,667
                             -----------   -----------   -----------   -----------  -----------  -----------
Segment contribution              15,332         9,080         5,251         4,997           --       34,660
Contribution margin                   35%           32%           43%           35%          --           35%
Depreciation and
    amortization expense           3,752         1,414           509         1,264           --        6,939
Interest expense                     560           494           136           459           --        1,649
Segment profit                    11,981         7,172         5,596         3,275           --       28,024

Segment assets                    41,029        19,481         9,370        12,987           --       82,867
Expenditures for
   segment assets                  1,997         2,797           373           910           --        6,077
</TABLE>


                                       6

<PAGE>   9

<TABLE>
<CAPTION>
Reconciliation of profits                                   1998                      1999
                                                     ------------------         -----------------
<S>                                                  <C>                        <C>
     Segment profit                                  $           28,024         $          36,256
     Unallocated amounts:
         Corporate general and administrative                    (7,035)                   (8,203)
         Corporate depreciation and amortization                 (1,416)                   (2,951)
         Corporate interest expense                              (3,493)                   (5,563)
                                                     ------------------         -----------------
     Income before taxes                             $           16,080         $          19,539
                                                     ==================         =================
</TABLE>

<TABLE>
<CAPTION>
Reconciliation of assets and expenditures                   1998                      1999
                                                     ------------------         -----------------
<S>                                                  <C>                        <C>
Assets:
     Segment amounts                                 $           82,867         $         147,283
     Corporate assets (including intangible assets)              63,400                    90,271
                                                     ------------------         -----------------
     Total assets                                    $          146,267         $         237,554
                                                     ==================         =================

Expenditures:
     Segment amounts                                 $            6,077         $          19,216
     Corporate expenditures                                       2,175                     2,984
                                                     ------------------         -----------------
     Total expenditures                              $            8,252         $          22,200
                                                     ==================         =================
</TABLE>

6. CONVERTIBLE NOTES

      On August 3, 1999, the Company issued $20,000,000 of eight-percent
convertible junior subordinated notes (the "Notes"). The Notes are convertible
into the Company's common stock at a conversion price of $8.625 per share, which
may be adjusted based on the performance of the stock prior to the second
anniversary of the issuance. The Notes were issued to DB Capital Partners, a
private equity arm and affiliate of Deutsche Bank.


                                       7
<PAGE>   10

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

      The following discussion of the results of operations and financial
condition of the Company should be read in conjunction with the Company's
consolidated financial statements and notes thereto included in the Annual
Report on Form 10-K/A for the year ended December 31, 1998, and with the
consolidated financial statements included in this Form 10-Q.

OVERVIEW

      Radiologix, Inc., a Delaware corporation (together with its subsidiaries,
"Radiologix" or the "Company"), develops, consolidates and manages radiology and
imaging center networks. The Company was incorporated in 1996, but conducted no
significant operations until November 26, 1997, when the Company consummated an
initial public offering ("IPO") and simultaneously exchanged cash and shares of
its common stock for certain assets of and liabilities associated with seven
radiology practices. These exchanges were accounted for using the historical
cost basis with the stock being valued at the historical cost of the net assets
received by the Company. Cash consideration given in these exchanges was treated
for accounting purposes as a dividend from the Company.

      Radiologix develops, consolidates and manages radiology service networks.
These networks consist primarily of free-standing diagnostic imaging centers and
locations at which the Company provides radiology services that have been
outsourced by hospitals. The Company's objective is to develop and operate
networks of radiology facilities to provide a full spectrum of radiology
services and extensive geographic coverage in existing market areas and in
selected new markets. As of November 15, 1999, Radiologix owns, operates or
maintains an ownership interest in imaging equipment at 119 locations and
provides management services to ten radiology practices consisting of 290
physicians who provide professional radiology services at certain of the
Company's radiology centers and at 59 hospitals. Radiologix's radiology networks
and facilities are in geographic markets located in Arizona, California,
Colorado, Florida, Georgia, Illinois, Kansas, Maryland, Minnesota, Missouri,
Nebraska, Nevada, New Jersey, New York, Ohio, Pennsylvania, Texas, the District
of Columbia and Virginia.

RESULTS OF OPERATIONS

Three Months Ended September 30, 1999

Service Fee Revenue

      Service fee revenue increased $12,191,000 or 34.8% in the third quarter of
1999 to $47,246,000 from $35,055,000 in the third quarter of 1998. Of the
increase from 1998 to 1999, $6,568,000 resulted from increased business within
existing facilities (19.3% same store increase), $4,313,000 resulted from
facilities acquired and developed in 1998, and $1,310,000 resulted from
"tuck-in" acquisitions of imaging centers since the end of the third quarter
1998.

Field Salaries and Benefits

      Salaries and benefits increased $2,767,000 or 25.8% in the third quarter
of 1999 to $13,505,000 from $10,738,000 in the third quarter of 1998. Of the
increase from 1998 to 1999, $1,636,000 resulted from existing facilities
representing a 15.5% same store increase, consistent with the revenue growth of
those centers. An increase of $750,000 resulted from facilities acquired and
developed in the latter half of 1998 and the remaining $381,000 resulted from
"tuck-in" acquisitions of imaging centers in 1998 and 1999. As a percentage of
service fee revenue, these costs were 28.6% and 30.6% in 1999 and 1998,
respectively.

Field Supplies

       Supplies increased $768,000 or 34.4% in the third quarter of 1999 to
$3,002,000 from $2,234,000 in the third quarter of 1998. Of the increase from
1998 to 1999, $9,000 resulted from existing facilities representing a 0.5% same
store increase. Supply expense has remained consistent on a same store basis as
a result of increasing purchasing power. An increase of $273,000 resulted from
facilities acquired and developed in the latter half of 1998 and the remaining
$486,000 resulted from


                                       8
<PAGE>   11

"tuck-in" acquisitions of imaging centers in 1998 and 1999. As a percentage of
service fee revenue, these costs were 6.4% in 1999 and 1998.

Field Rent and Lease Expense

       Rent and lease expense increased $2,634,000 or 98.4% in the third quarter
of 1999 to $5,311,000 from $2,677,000 in the third quarter of 1998. Of the
increase from 1998 to 1999, $1,519,000 resulted from existing facilities
representing a 58.1% same store increase. This increase is attributable to
several MRI leases in the Northeast region that are based on a per scan basis.
As volume increases, which is evident in the increased same store revenue
numbers, equipment lease expense increases due to per scan payment arrangements
increased. An increase of $936,000 resulted from facilities acquired and
developed in the latter half of 1998 and the remaining $179,000 resulted from
"tuck-in" acquisitions of imaging centers in 1998 and 1999. As a percentage of
service fee revenue, these costs were 11.2% and 7.6% in 1999 and 1998,
respectively.

Other Field Expenses

      Other expenses increased $1,155,000 or 16.0% in the third quarter of 1999
to $8,375,000 from $7,220,000 in the third quarter of 1998. Of the increase from
1998 to 1999, $186,000 resulted from existing facilities representing a 2.6%
same store increase. An increase of $813,000 resulted from facilities acquired
and developed in 1998, and $156,000 resulted from "tuck-in" acquisitions of
imaging centers in 1998 and 1999. As a percentage of service fee revenue, these
costs were 17.7% and 20.6% in 1999 and 1998, respectively.

Corporate General and Administrative

      Corporate general and administrative expenses increased $315,000 or 12.1%
in the third quarter of 1999 to $2,910,000 from $2,595,000 in the third quarter
of 1998. This increase was principally due to the continued development of the
Company's infrastructure and the addition of staff related to the Questar
Imaging, Inc. transaction (see Note 3 to the Consolidated Financial Statements).
As a percentage of service fee revenue, these costs were 6.2% and 7.4% in 1999
and 1998, respectively.

Depreciation and Amortization

      Depreciation and amortization increased $2,117,000 or 71.1% in the third
quarter of 1999 to $5,093,000 from $2,976,000 in the third quarter of 1998. This
increase was principally due to amortization of intangible assets resulting from
the Company's acquisition of additional facilities and practices. In addition,
the Company has continued to buy new equipment to replace older equipment and
this upgrade of equipment resulted in increased depreciation expense. As a
percentage of service fee revenue, these costs were 10.8% and 8.5% in 1999 and
1998, respectively.

Interest Expense, net

      Interest expense, net increased $1,329,000 or 64.7% in the third quarter
of 1999 to $3,383,000 from $2,054,000 in the third quarter of 1998. As a
percentage of service fee revenue, these costs were 7.2% and 5.9% in 1999 and
1998, respectively. The increase (as a percentage of service fee revenue) is a
result of the Company's acquisitions throughout 1999, an increase in days sales
outstanding and the issuance of $20,000,000 of convertible notes to fund the
Questar Imaging, Inc. transaction, all of which resulted in the Company carrying
higher debt levels.

Income Taxes

      The Company's effective tax rates for the third quarters of 1999 and 1998
were 40.0% and 38.0%, respectively. The increase in the effective tax rate is
primarily attributed to acquisitions in which the Company has acquired the stock
of the target. In a stock purchase, the goodwill associated with the transaction
is not deductible for tax purposes and, therefore, increases the effective tax
rate. The Company has not recognized any income tax benefit for operating losses
incurred in 1997 and 1996. The Company will continue to carry the losses with a
fully reserved valuation allowance. The Company will recognize the tax benefit
at such time as it is deemed reasonably certain of realization.


                                       9
<PAGE>   12

Net Income

      As a result of the foregoing factors, the Company generated net income of
$3,835,000 for the three months ended September 30, 1999, or diluted income per
share of $0.19 on 21,246,000 shares outstanding, compared to net income of
$3,408,000 for the three months ended September 30, 1998, or diluted income per
share of $0.18 on 19,356,000 shares outstanding.

Nine Months Ended September 30, 1999

Service Fee Revenue

      Service fee revenue increased $30,865,000 or 31.4% in the first nine
months of 1999 to $129,192,000 from $98,327,000 in the first nine months of
1998. Of the increase from 1998 to 1999, $17,988,000 resulted from increased
business within existing facilities (19.1% same store increase), $4,773,000
resulted from facilities acquired and developed in 1998, and $8,104,000 resulted
from "tuck-in" acquisitions of imaging centers in 1998 and 1999.

Field Salaries and Benefits

      Salaries and benefits increased $7,681,000 or 25.2% in the first nine
months of 1999 to $38,128,000 from $30,447,000 in the first nine months of 1998.
Of the increase from 1998 to 1999, $4,985,000 resulted from existing facilities
representing a 16.7% same store increase, consistent with the revenue growth of
those centers. An increase of $1,134,000 resulted from facilities acquired and
developed in 1998 and the remaining $1,562,000 increase resulted from "tuck-in"
acquisitions of imaging centers in 1998 and 1999. As a percentage of service fee
revenue, these costs were 29.5% and 31.0% in 1999 and 1998, respectively.

Field Supplies

       Supplies increased $1,930,000 or 30.2% in the first nine months of 1999
to $8,321,000 from $6,391,000 in the first nine months of 1998. Of the increase
from 1998 to 1999, $291,000 resulted from facilities acquired and developed in
1998 and $1,704,000 resulted from "tuck-in" acquisitions of imaging centers in
1998 and 1999, offset by a $65,000 decrease in same store expenses. As a
percentage of service fee revenue, these costs were 6.4% and 6.5% in 1999 and
1998, respectively.

Field Rent and Lease Expense

       Rent and lease expense increased $4,667,000 or 56.9% in the first nine
months of 1999 to $12,872,000 from $8,205,000 in the first nine months of 1998.
Of the increase from 1998 to 1999, $2,889,000 resulted from existing facilities
representing a 36.2% same store increase. This increase is attributable to
several MRI leases in the Northeast region that are based on a per scan basis.
As volume increases, which is evident in the increased same store revenue
numbers, equipment lease expense increases due to per scan payment arrangement
associated with these higher end modalities. An increase of $897,000 resulted
from facilities acquired and developed in 1998 and the remaining $881,000
resulted from "tuck-in" acquisitions of imaging centers in 1998 and 1999. As a
percentage of service fee revenue, these costs were 10.0% and 8.3% in 1999 and
1998, respectively.

Other Field Expenses

      Other expenses increased $4,069,000 or 21.9% in the first nine months of
1999 to $22,693,000 from $18,624,000 in the first nine months of 1998. Of the
increase from 1998 to 1999, $1,925,000 resulted from existing facilities
representing a 10.9% same store increase. An increase of $1,010,000 resulted
from facilities acquired and developed in 1998, and the remaining $1,134,000
resulted from "tuck-in" acquisitions of imaging centers in 1998 and 1999. As a
percentage of service fee revenue, these costs were 17.6% and 18.9% in 1999 and
1998, respectively.


                                       10
<PAGE>   13

Corporate General and Administrative

      Corporate general and administrative increased $1,169,000 or 16.6% in the
first nine months of 1999 to $8,203,000 from $7,034,000 in the first nine months
of 1998. This increase was principally due to the continued development of the
Company's infrastructure and the addition of staff related to the Questar
Imaging, Inc. transaction (see Note 3 to the Consolidated Financial Statements).
As a percentage of service fee revenue, these costs were 6.4% and 7.2% in 1999
and 1998, respectively.

Depreciation and Amortization

      Depreciation and amortization increased $4,594,000 or 55.0% in the first
nine months of 1999 to $12,949,000 from $8,355,000 in the first nine months of
1998. This increase was principally due to amortization of goodwill resulting
from the Company's acquisition of additional facilities and practices. In
addition, the Company has continued to buy new equipment to replace older
equipment and this upgrade of equipment resulted in increased depreciation
expense. As a percentage of service fee revenue, these costs were 10.0% and 8.5%
in 1999 and 1998, respectively.

Interest Expense, Net

      Interest expense, net increased $3,154,000 or 61.3% in the first nine
months of 1999 to $8,296,000 from $5,142,000 in the first nine months of 1998.
As a percentage of service fee revenue, these costs were 6.4% and 5.2% in 1999
and 1998, respectively. The increase as a percentage of service fee revenue is a
result of the Company's acquisitions throughout 1999, resulting in higher debt
levels.

Income Taxes

      The Company's effective tax rates for the first nine months of 1999 and
1998 were 38.5% and 38.6%, respectively. The Company has not recognized any
income tax benefit for operating losses incurred in 1997 and 1996. The Company
will continue to carry the losses with a fully reserved valuation allowance. The
Company will recognize the tax benefit at such time as it is deemed reasonably
certain of realization.

Net Income

      As a result of the foregoing factors, the Company generated net income of
$12,007,000 for the nine months ended September 30, 1999, or diluted income per
share of $0.60 on 20,238,000 shares outstanding, compared to net income of
$9,872,000 for the nine months ended September 30, 1998, or diluted income per
share of $0.51 on 19,219,000 shares outstanding.

Liquidity and Capital Resources

      At September 30, 1999, the Company had $42,403,000 in working capital, an
increase of $23,025,000 from December 31, 1998. The Company's principal sources
of liquidity consist of: (i) cash and cash equivalents aggregating $7,352,000;
(ii) net accounts receivable of $59,969,000; and (iii) approximately $18,000,000
in borrowing capacity under the Company's bank credit facility (the "Credit
Facility").

      For the nine months ended September 30, 1999, $1,643,000 was provided by
operations. Cash of $45,927,000 was used in investing activities in the first
nine months of 1999, $24,641,000 of which was related to certain acquisitions,
$22,200,000 related to the purchase of property and equipment and $914,000 net
was received from joint ventures. Cash of $45,151,000 was provided by financing
activities in the first nine months of 1999, $20,000,000 of which resulted from
the issuance of convertible notes at the beginning of August 1999.

      For the nine months ended September 30, 1998, $10,239,000 was provided by
operations. Cash provided by operations decreased $8,596,000 in the first nine
months of 1999 from the first nine months of 1998 primarily due to an increase
in accounts receivable during the first nine months of 1999. Cash of $61,743,000
was used in investing activities, primarily related to certain acquisitions.
Cash of $51,922,000 was provided by financing activities, primarily through
borrowings under the Credit Facility.


                                       11
<PAGE>   14

      On November 26, 1997, the Company entered into the Credit Facility. The
Credit Facility was amended August 3, 1999. The loan agreement provides for
revolving loans of up to $160,000,000 to be used by the Company for acquisitions
and general working capital needs. The Company may borrow, repay and reborrow
amounts during the first three years of the Credit Facility. Amounts outstanding
under the Credit Facility at the end of three years are required to be repaid in
quarterly installments of varying amounts commencing September 30, 2000. The
Credit Facility expires and all loans thereunder mature on the sixth anniversary
of the closing date of the Credit Facility. Borrowings under the Credit Facility
at any time may not exceed the lesser of $160,000,000 or 3.25 times the
consolidated EBITDA of the Company, giving pro forma effect to acquisitions made
with such borrowings. In accordance with the Credit Facility, the Company's
senior debt under all senior credit arrangements could not exceed $187,109,000
at September 30, 1999. As of September 30, 1999, the Company had outstanding
borrowings of $142,000,000 under the Credit Facility and an additional
$23,767,000 outstanding under other senior credit arrangements. At the Company's
option, the interest rate under the Credit Facility is (i) an adjusted LIBOR
rate, plus an applicable margin which can vary from 1.5% to 2.5% dependent on
certain financial ratios or (ii) the prime rate, plus an applicable margin which
can vary from 0.5% to 1.5%. In each case, the applicable margin varies based on
financial ratios maintained by the Company. The Credit Facility includes certain
restrictive covenants including prohibitions on the payment of dividends and the
maintenance of certain financial ratios (including minimum debt-service coverage
and maximum debt-to-EBITDA coverage, as defined). Borrowings under the Credit
Facility are secured by all service agreements to which the Company is, or
becomes a party to, and a pledge of the stock of the Company's subsidiaries.

      On August 3, 1999, the Company issued $20,000,000 of eight-percent (8%)
convertible junior subordinated notes (the "Notes"). The Notes are convertible
into the Company's common stock at a conversion price of $8.625 per share, which
may be adjusted based on the performance of the stock prior to the second
anniversary of the issuance. The Notes were issued to DB Capital Partners, a
private equity arm and affiliate of Deutsche Bank.

       The Company may source other debt or equity financing to facilitate its
growth strategy. In the event the Company is unsuccessful in obtaining
additional financing, the Company anticipates that funds generated from
operations, cash and cash equivalents, and funds available under the Credit
Facility will be sufficient to meet the Company's working capital requirements
and debt obligations and to finance any necessary capital expenditures through
the end of 1999.


YEAR 2000 ISSUE

Impact of Year 2000

      The Year 2000 issue (the "Year 2000 Issue") exists because many computer
systems and applications currently use two-digit date fields to designate a
year. As the century date occurs, computer programs, computers and embedded
microprocessors controlling equipment with date-sensitive systems may recognize
the Year 2000 as 1900, or not at all. This inability to recognize or properly
treat the Year 2000 date fields may result in computer system failures or
miscalculations of critical financial and operational information, as well as
failures of equipment controlling date-sensitive microprocessors. In addition,
Year 2000 is a leap year and this too could lead to miscalculations or failures
at the end of February, 2000.

State of Readiness

      The Company started to formulate a plan to address the Year 2000 Issue in
the third quarter of 1998. The Company's Year 2000 Plan ("Year 2000 Plan")
focuses on: (i) diagnostic imaging equipment utilized in its imaging operations;
(ii) internal information technology systems, including all types of systems
used by the Company in its operations, finance, materials management and human
resources departments; and (iii) information systems of its customers, payors
and vendors. The Year 2000 Plan for each of these areas involves the following
phases: awareness, assessment, renovation, testing and implementation. The
Company has completed the awareness and assessment phases and has made
significant progress in renovating noncompliant systems. In addition, the
Company has established a timeline for the testing and implementation phases.
The aforementioned areas are securing Year 2000 compliant certificates and
statements for documentation/cataloging purposes. In general, the Company's goal
is to complete all phases of the Year 2000 Plan by November 30, 1999, although
complications arising from vendor delays may cause some delay.



                                       12
<PAGE>   15

      Most of the Company's diagnostic imaging equipment used to provide imaging
services in the Company's imaging centers have computer systems and
applications, and in some cases, embedded microprocessors, that could be
affected by Year 2000 Issues. The Company assessed the impact on its diagnostic
imaging equipment by contacting the vendors of such equipment to determine their
state of readiness in relation to each piece of equipment. The vendors with
respect to 99% of imaging equipment used by the Company have informed the
Company that the imaging equipment is either now Year 2000 compliant or will be
Year 2000 compliant with updates planned for installation before November 30,
1999. The vendors with respect to the remaining one percent (1%) of imaging
equipment have informed the Company that: (i) they have developed software to
ensure Year 2000 compliance with respect to the balance of their non-compliant
imaging equipment; (ii) renovation will be made during future regular
maintenance visits; or (iii) they have developed functional work arounds to
ensure there are no Year 2000 problems. The Company expects that renovation will
be completed by November 30, 1999, and that, as of October 31, 1999, 90% of its
diagnostic imaging equipment was Year 2000 compliant.

      The Company's information systems technology are known to be 85%
compliant. These systems include those that have been modified including
modifying and upgrading software and developing and purchasing new software. The
Company continues to renovate and test the remaining portions of such systems
and to assess the potential for Year 2000 problems with the embedded
microprocessors in its other equipment, facilities and corporate and regional
offices, including telecommunications systems, utilities, dictation systems,
security systems and HVACS. The Company expects to complete the renovation and
testing phases for such systems by November 30, 1999.

      During the third quarter of 1999, the Company implemented a plan to assess
the potential for Year 2000 problems with the information systems of its
customers, payors and vendors. The Company prepared and sent questionnaires to
its customers, vendors and other third parties with which the Company has a
material relationship. The Company recently completed its assessment with
respect to such parties. While the Company has received preliminary information
concerning the Year 2000 readiness of many of its customers, vendors and other
third parties with which the Company has material relationships, the Company
does not have sufficient information to provide an estimated timetable for
completion of renovation and testing that such third parties with which the
Company has a material relationship may undertake. As a result, the Company is
unable to estimate the costs that it may incur to remedy the Year 2000 issues
relating to such parties. The Company expects to engage in discussions with the
noncompliant parties in an attempt to determine the extent to which the Company
is vulnerable to those parties' possible failure to become Year 2000 compliant.

Costs to Address Year 2000 Issue

       The Company estimates, on a preliminary basis, that the cost of
assessment, renovation, testing and implementation of its internal systems will
range from approximately $500,000 to $750,000. The major components of these
costs are consultants, additional personnel costs, programming, new software and
hardware, software upgrades and travel expenses. The Company expects that such
costs will be funded through operating cash flows. This estimate, based on
currently available information, will be updated as the Company continues its
assessment and proceeds with renovation, testing and implementation, and may be
adjusted upon receipt of more information from the Company's vendors, customers
and other third parties and upon the design and implementation of the Company's
contingency plan. In addition, the availability and cost of consultants and
other personnel trained in this area and unanticipated acquisitions might
materially affect the estimated costs. The effects of the aforementioned costs
have had no material impact on the Company's progress as it relates to other
information system projects and implementation.

Risks to the Company

      The Company's Year 2000 Issue involves significant risks. There can be no
assurance that the Company will succeed in implementing all of its Year 2000
Plan. The following describes the Company's most reasonably likely worst-case
scenario, given current uncertainties. If the Company's renovated or replaced
internal information technology systems fail the testing phase, or any software
application or embedded microprocessors central to the Company's operations are
overlooked in the assessment or implementation phases, significant problems,
including delays, may be incurred in billing the Company's major customers
(Medicare, HMOs or private insurance carriers) for services performed. If its
major customers' systems do not become Year 2000 compliant on a timely basis,
the Company will have problems and incur delays in receiving and processing
correct reimbursements. If the computer systems of third parties (including
hospitals) with which the Company's systems exchange data do not become Year
2000 compliant, both on a timely basis and in a manner compatible with continued
data exchange with the Company's information technology systems, significant
problems may be incurred in billing and


                                       13
<PAGE>   16

reimbursement. If the systems on the diagnostic imaging equipment utilized by
the Company are not Year 2000 compliant, the Company may not be able to provide
imaging services to patients. If the Company's vendors or suppliers of the
Company's necessary power, telecommunications, transportation and financial
services fail to provide the Company with equipment and services, the Company
will be unable to provide services to its customers. If any of these
uncertainties were to occur, the Company's business, financial condition and
results of operations would be adversely affected. The Company is unable to
assess the likelihood of such events occurring or the extent of the effect on
the Company.

Forward-Looking Statements

      This report contains or may contain forward-looking statements within the
meaning of Section 21E of the Securities Exchange Act of 1934 including
statements of the Company's and management's expectations, intentions, plans and
beliefs, including those contained in or implied by "Management's Discussion and
Analysis of Financial Condition and Results of Operations." These
forward-looking statements, as defined in Section 21E of the Securities Exchange
Act of 1934, are dependent on certain events, risks and uncertainties that may
be outside of the Company's control. These forward-looking statements may
include statements of management's plans and objectives for the Company's future
operations and statements of future economic performance; the Company's capital
budget and future capital requirements, and the Company's meeting its future
capital needs; and the assumptions described in this report underlying such
forward-looking statements. Actual results and developments could differ
materially from those expressed in or implied by such statements due to a number
of factors, including, without limitation, those described in the context of
such forward-looking statements.


ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

      The Company's exposure to market risk for changes in interest rates
relates primarily to the Company's cash equivalents, Credit Facility, and its
convertible notes.


                                       14
<PAGE>   17

                           PART II: OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

      From time to time the Company is subject to certain legal proceedings and
claims which arise in the normal course of its business. Pending matters include
claims relating to professional services provided by a founding affiliated
practice. There can be no assurances that additional claims will not be asserted
against the Company in the future. The Company became subject to certain of the
pending claims as the result of successor liability in connection with the
acquisition of the founding affiliated practices; however, the Company believes
that the ultimate resolution of such claims net of applicable indemnification
and available insurance will not have a material adverse effect on the business,
financial condition or results of operations of the Company.

      There can be no assurance that the Company will not subsequently be named
as a defendant in additional lawsuits. Each existing radiology practice has
retained responsibility for, and agreed to indemnify the Company in full
against, the liabilities associated with certain lawsuits. In the event the
Company is named or subsequently added as a party to these lawsuits, or a
monetary judgment is entered against the Company and indemnification is
unavailable for any reason, the Company's business, financial condition and
results of operations could be materially adversely affected.

ITEM 2. CHANGES IN SECURITIES AND USE OF PROCEEDS

      Not Applicable

ITEM 3. DEFAULTS UPON SENIOR SECURITIES

      Not Applicable

ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

      Not Applicable

ITEM 5. OTHER INFORMATION

      Not Applicable

ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K

      (a) Exhibits. See Index to Exhibits following signatures.

      (b) Reports on Form 8-K

      On Form 8-K dated August 18, 1999, Radiologix, Inc. announced that it had
acquired all the outstanding stock of Questar Imaging, Inc. of Tampa, Florida
("Questar"). The Questar purchase price was financed through the issuance of $20
million in principal amount of junior convertible subordinated notes that
initially bear interest at a rate of eight percent, which may be adjusted in
certain circumstances, to BT Capital Partners SBIC, L.P., a private equity arm
and affiliate of Deutsche Bank, in a private transaction. The notes are
convertible into common stock of the Company at an initial conversion price of
$8.625, which may be adjusted in certain circumstances.

      On Form 8-K dated September 24, 1999, the Company announced the change of
its corporate name from American Physician Partners, Inc. to Radiologix, Inc.
pursuant to a merger with a wholly-owned subsidiary effected under Delaware law.


                                       15
<PAGE>   18

                                   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 thereunto duly authorized.


                                           RADIOLOGIX, INC.


Date: November 15, 1999                    /s/ MARK L. WAGAR
                                           -------------------------------------
                                           Mark L. Wagar
                                           Chairman of the Board,
                                           President and Chief Executive Officer
                                           (Principal Executive Officer)

Date: November 15, 1999                    /s/ SAMI S. ABBASI
                                           -------------------------------------
                                           Sami S. Abbasi
                                           Senior Vice President and
                                           Chief Financial Officer
                                           (Principal Financial Officer)


Date: November 15, 1999                    /s/ DAVID W. YOUNG
                                           -------------------------------------
                                           David W. Young
                                           Treasurer and Controller
                                           (Principal Accounting Officer)



                                       16
<PAGE>   19

                                INDEX TO EXHIBITS

<TABLE>
<CAPTION>
  EXHIBIT
   NUMBER                          DESCRIPTION
  -------                          -----------
  <S>       <C>
      2.1   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and among American Physician Partners, Inc., Carroll Imaging
            Associates, P.A., Diagnostic Imaging Associates, P.A., Drs.
            Copeland, Hyman and Shackman, P.A., Drs. Decarlo, Lyon, Hearn &
            Pazourek, P.A., Drs. Thomas, Wallop, Kim & Lewis, P.A., Harbor
            Radiologists, P.A., and Perilla, Syndler & Associates, P.A. **

      2.2   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., Radiology and
            Nuclear Medicine, A Professional Association. **

      2.3   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Mid Rockland
            Imaging Associates, P.C.**

      2.4   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Rockland
            Radiological Group, P.C.**

      2.5   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Advanced
            Imaging of Orange County, P.C. **

      2.6   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Central
            Imaging Associates, P.C. **

      2.7   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Nyack Magnetic
            Resonance Imaging, P.C. **

      2.8   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Pelham Imaging
            Associates, P.C. **

      2.9   Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Women's
            Imaging Consultants, P.C. **

      2.10  Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Pacific
            Imaging Consultants, A Medical Group, Inc. **

      2.11  Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Total Medical
            Imaging, Inc.**

      2.12  Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and Valley
            Radiologists Medical Group, Inc. **

      2.13  Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and The Ide Group,
            P.C. **

      2.14  Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and M&S X-Ray
            Associates, P.A. **

      2.15  Agreement and Plan of Reorganization and Merger, dated June 27, 1997
            by and between American Physician Partners, Inc., and South Texas
            MR, Inc. **

      2.16  Agreement and Plan of Exchange, dated June 27, 1997 by and between
            American Physician Partners, Inc., and San Antonio MR, Inc. **

      2.17  Agreement and Plan of Exchange, dated June 27, 1997 by and among
            American Physician Partners, Inc., Lexington MR, Ltd. and the
            Sellers. **

      2.18  Agreement and Plan of Exchange, dated June 27, 1997 by and among
            American Physician Partners, Inc., Madison Square Joint Venture and
            the Sellers. **

      2.19  Agreement and Plan of Exchange, dated June 27, 1997 by and among
            American Physician Partners, Inc., South Texas No. 1 MRI Limited
            Partnership, a Texas limited partnership, and the Sellers. **

      2.20  Agreement and Plan of Exchange, dated June 27, 1997 by and among
            American Physician Partners, Inc., San Antonio MRI Partnership No. 2
            Ltd., a Texas limited partnership, and the Sellers**

      2.21  Agreement and Plan of Exchange, dated June 27, 1997 by and between
            American Physician Partners, Inc., and the Sellers **
</TABLE>


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<PAGE>   20

<TABLE>
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      2.22  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and among American
            Physician Partners, Inc., Carroll Imaging Associates, P.A.,
            Diagnostic Imaging Associates, P.A., Drs. Thomas, Wallop, Kim &
            Lewis, P.A., Drs. Copeland, Hyman & Shackman, P.A., Drs. DeCarlo,
            Lyon, Hearn & Pazourek, P.A., Harbor Radiologists, P.A., and
            Perilla, Sindler & Associates, P.A.**

      2.23  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Radiology and Nuclear Medicine, A
            Professional Association.**

      2.24  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Mid Rockland Imaging Associates,
            P.C.**

      2.25  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Rockland Radiological Group, P.C.**

      2.26  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Advanced Imaging of Orange County,
            P.C.**

      2.27  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Central Imaging Associates, P.C.**

      2.28  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Nyack Magnetic Resonance Imaging,
            P.C.**

      2.29  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Pelham Imaging Associates, P.C.**

      2.30  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Women's Imaging Consultants, P.C.**

      2.31  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Pacific Imaging Consultants, A Medical
            Group, Inc.**

      2.32  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Total Medical Imaging, Inc.**

      2.33  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and Valley Radiologists Medical Group,
            Inc.**

      2.34  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and The Ide Group, P.C.**

      2.35  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and M & S X-Ray Associates, P.A.**

      2.36  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and South Texas MR, Inc.**

      2.37  Amendment No. 1 to the Agreement and Plan of Reorganization and
            Merger, dated as of September 30, 1997, by and between American
            Physician Partners, Inc., and San Antonio MR, Inc.**

      2.38  Amendment No. 1 to the Agreement and Plan of Exchange, dated
            September 30, 1997, by and between American Physician Partners,
            Inc., and Lexington MR, Ltd.**

      2.39  Amendment No. 1 to the Agreement and Plan of Exchange, dated
            September 30, 1997, by and between American Physician Partners,
            Inc., and Madison Square Joint Venture.**

      2.40  Amendment No. 1 to the Agreement and Plan of Exchange, dated
            September 30, 1997, by and between American Physician Partners,
            Inc., and South Texas No. 1 MRI Limited Partnership.**

      2.41  Amendment No. 1 to the Agreement and Plan of Exchange, dated
            September 30, 1997, by and between American Physician Partners,
            Inc., and San Antonio MRI Partnership No. 2, Ltd.**

      2.42  Asset Purchase Agreement, dated as of January 1, 1998, by and among
            American Physician Partners, Inc., Community Radiology Associates,
            Inc., Drs. Korsower and Pion Radiology, P.A., and the Principal
            Stockholders ****
</TABLE>



                                       18
<PAGE>   21
<TABLE>
  <S>       <C>
      2.43  Asset Purchase Agreement, dated as of January 12, 1998, by and among
            American Physician Partners, Inc., Valley Imaging Partners, Inc.,
            Questar Imaging, Inc. and Questar Imaging VR, Inc. ****

      2.44  Asset Purchase Agreement, dated as of January 23, 1998, by and among
            American Physician Partners, Inc., Valley Imaging Partners, Inc.,
            PAL Imaging Corp. and the Principal Stockholders ****

      2.45  Asset Purchase Agreement, dated as of April 1, 1998, by and among
            American Physician Partners, Inc., Treasure Coast Imaging Partners,
            Inc. and Radiology Imaging Associates, Basilico, Gallagher and
            Raffa, M.D., P.A. and Robert F. Basilico, M.D., Edward Gallagher,
            M.D., R.J. Raffa, M.D., Joseph T. Charles, M.D., Alex N. Vennos,
            M.D., and Robin J. Connolly, M.D.*****

      2.46  Asset Purchase Agreement, dated as of April 1, 1998, by and among
            American Physician Partners, Inc., Treasure Coast Imaging Partners,
            Inc. and St. Lucie Imaging and Breast Center, Inc. and Robert F.
            Basilico, M.D., Edward Gallagher, M.D., R.J. Raffa, M.D., Joseph T.
            Charles, M.D., Alex N. Vennos, M.D., and Robin J. Connolly,
            M.D.*****

      2.47  Asset Purchase Agreement, dated as of April 28, 1998, by and among
            American Physician Partners, Inc., Valley Imaging Partners, Inc.,
            LXL, Ltd. and the Partners of LXL, Ltd.*****

      2.48  Asset Purchase Agreement, dated as of June 1, 1998, by and among
            American Physician Partners, Inc., Mid Rockland Imaging Partners,
            Inc., Empire State Imaging Partners, Inc., RF Management Corp. and
            Modern Medical Modalities Corporation*****

      2.49  Asset Purchase Agreement, dated as of June 23, 1998, by and among
            American Physician Partners, Inc., Valley Imaging Partners, Inc.,
            Brewster Imaging Center, Inc. and Each Principal Stockholder*****

      2.50  Asset Purchase Agreement, dated as of June 29, 1998, by and among
            American Physician Partners, Inc., Valley Imaging Partners, Inc. and
            Bryan M. Shieman, M.D., a sole proprietorship d/b/a El Camino Center
            for Osteoporosis and/or ECOO II*****

      2.51  Stock Purchase Agreement, dated September 1, 1998, by and among
            American Physician Partners, Inc., WB&A Imaging Partners, Inc. and
            Vimla Bhooshan, M.D., John B. DeGrazia, M.D., Edwin Goldstein, M.D.,
            Paul T. Lubar, M.D., Calvin D. Neithamer, M.D., William P. O'Grady,
            M.D., Robert A. Olshaker, M.D., Stanley M. Perl, M.D., Michael S.
            Usher, M.D., Alan B. Kronthal, M.D., Steven A. Meyers, M.D., Victor
            A. Bracey, M.D. and Larry W. Busching ******

      2.52  Asset Purchase Agreement, dated September 1, 1998, by and among
            American Physician Partners, Inc., Ormond Imaging Partners, Inc.,
            Magnetic Resonance Imaging Associates Limited Partnership and Paul
            T. Lubar, Stanley M. Perl, Michael S. Usher, John B. DeGrazia, Larry
            W. Busching, Vimla Bhooshan, William P. O'Grady, Robert A. Olshaker,
            and Calvin D. Neithamer ******

      2.53  Asset Purchase Agreement, dated September 1, 1998, by and among
            American Physician Partners, Inc., Ormond Imaging Partners, Inc.,
            Duke Associates Limited Partnership and Paul T. Lubar, Stanley M.
            Perl, Michael S. Usher, John B. DeGrazia, Larry W. Busching, Vimla
            Bhooshan, William P. O'Grady, Edwin Goldstein, Robert A. Olshaker,
            Calvin D. Neithamer and Alan J. Kronthal ******

      2.54  Stock Purchase Agreement effective as of August 1, 1999 by and among
            American Physician Partners, Inc., Questar Imaging, Inc. and the
            shareholders of Questar Imaging, Inc. ********

      3.1   Restated Certificate of Incorporation of American Physician
            Partners, Inc.***

      3.2   Amended and Restated Bylaws of American Physician Partners, Inc.***

      3.3   Amendment to Restated Certificate of Incorporation of American
            Physician Partners, Inc. *********

      3.4   Amendment to Restated Bylaws of American Physician Partners, Inc.
            *********

      4.1   Form of certificate evidencing ownership of Common Stock of American
            Physician Partners, Inc.***

      4.2   Form of Convertible Promissory Note of American Physician Partners,
            Inc.**

      4.3   Securities Purchase Agreement dated as of August 3, 1999 by and
            between American Physician Partners, Inc. and BT Capital Partners
            SBIC, L.P. ********

      4.4   Convertible Junior Subordinated Promissory Note dated August 1, 1999
            issued to BT Capital Partners SBIC, L.P. ********

      10.1  American Physician Partners, Inc. 1996 Stock Option Plan.**

      10.2  Employment Agreement between American Physician Partners, Inc. and
            Gregory L. Solomon.**

      10.3  Employment Agreement between American Physician Partners, Inc. and
            Mark S. Martin.**

      10.4  Employment Agreement between American Physician Partners, Inc. and
            Sami S. Abbasi.**

      10.5  Employment Agreement between American Physician Partners, Inc. and
            Paul M. Jolas.**

      10.6  Form of Indemnification Agreement for certain Directors and
            Officers.***
</TABLE>


                                       19
<PAGE>   22

<TABLE>
  <S>       <C>
      10.7  Form of Registration Rights Agreement.**

      10.8  Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., APPI-Advanced Radiology, Inc. and Carroll
            Imaging Associates, P.A., Diagnostic Imaging Associates, P.A., Drs.
            Thomas, Wallop, Kim & Lewis, P.A., Drs. Copeland, Hyman and
            Shackman, P.A., Drs. Decarlo, Lyon, Hearn & Pazourek, P.A., Harbor
            Radiologists, P.A., Perilla, Sindler & Associates, P.A.**

      10.9  Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Ide Admin Corp. and Ide Imaging Group,
            P.C.**

      10.10 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., M & S X-Ray Associates, P.A. and M&S
            Imaging Associates, P.A.**

      10.11 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Rockland Radiological Group, P.C. and The
            Greater Rockland Radiological Group, P.C.**

      10.12 Service Agreement dated November , by and among American Physician
            Partners, Inc., Advanced Imaging of Orange County, P.C. and The
            Greater Rockland Radiological Group, P.C.**

      10.13 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Central Imaging Associates, P.C. and The
            Greater Rockland Radiological Group, P.C.**

      10.14 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Nyack Magnetic Resonance Imaging, P.C. and
            The Greater Rockland Radiological Group, P.C.**

      10.15 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Pelham Imaging Associates, P.C. and The
            Greater Rockland Radiological Group, P.C.**

      10.16 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Women's Imaging Consultants, P.C. and The
            Greater Rockland Radiological Group, P.C.**

      10.17 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., APPI-Pacific Imaging Inc. and PIC Medical
            Group, Inc.**

      10.18 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., Radiology and Nuclear Medicine, a
            Professional Association and RNM L.L.C.**

      10.19 Service Agreement dated November 26, 1997, by and among American
            Physician Partners, Inc., APPI-Valley Radiology, Inc. and Valley
            Radiology Medical Associates, Inc.**

      10.20 Consulting Agreement between American Physician Partners, Inc. and
            Michael L. Sherman, M.D.***

      10.21 Office Building Lease Agreement between Dallas Main Center Limited
            Partnership and American Physician Partners, Inc.***

      10.22 First Amendment to Office Building Lease Agreement between Dallas
            Main Center Limited Partnership and American Physician Partners,
            Inc.***

      10.23 Credit Agreement by and among American Physician Partners, Inc., GE
            Capital Corporation and the other credit parties signatory
            thereto.***

      10.24 Consulting Agreement between American Physician Partners, Inc. and
            Lawrence R. Muroff, M.D.***

      10.25 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Lawrence Muroff, M.D.***

      10.26 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Mark Martin.***

      10.27 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Sami Abbasi.***

      10.28 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Gregory L. Solomon.***

      10.29 First Amendment to Consulting Agreement between American Physician
            Partners, Inc. and Lawrence R. Muroff, M.D.***

      10.30 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Michael Sherman, M.D.***

      10.31 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Paul M. Jolas.***

      10.32 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Derace Schaffer, M.D.***

      10.33 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and John Pappajohn.***

      10.34 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Mary Pappajohn.***
</TABLE>


                                       20
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      10.35 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Thebes Ltd.***

      10.36 Side Letter dated November 12, 1997 by and between American
            Physician Partners, Inc. and Halkis Ltd.***

      10.37 Service Agreement dated January 1, 1998, by and among American
            Physician Partners, Inc., Community Imaging Partners, Inc.,
            Community Radiology Associates, Inc. and Drs. Korsower and Pion
            Radiology, P.A.****

      10.38 Service Agreement dated April 1, 1998, by and among American
            Physician Partners, Inc., Treasure Coast Imaging Partners, Inc. and
            Radiology Imaging Associates - Basilico, Gallagher & Raffa, M.D.,
            P.A. *****

      10.39 First Amendment to Credit Agreement and Consent dated May 19, 1998,
            by and among American Physician Partners, Inc., General Electric
            Capital Corporation and the other credit parties signatory
            thereto*****

      10.40 Employment Agreement between American Physician Partners, Inc. and
            Mark L. Wagar*****

      10.41 Service Agreement dated September 1, 1998, by and among American
            Physician Partners, Inc., WB&A Imaging Partners, Inc. and WB&A
            Imaging, P.C. ******

      10.42 Office Building Lease Agreement between The Equitable-Nissei Dallas
            Company and Fibreboard Corporation ******

      10.43 Office Building Sublease Agreement by and between Fibreboard
            Corporation and American Physician Partners, Inc. ******

      10.44 First Amendment to Employment Agreement between American Physician
            Partners, Inc. and Mark L. Wagar *******

      10.45 First Amendment to Employment Agreement between American Physician
            Partners, Inc. and Mark S. Martin *******

      10.46 First Amendment to Employment Agreement between American Physician
            Partners, Inc. and Sami S. Abbasi *******

      10.47 First Amendment to Employment Agreement between American Physician
            Partners, Inc. and Paul M. Jolas *******

      10.48 Amendment No. 1 to American Physician Partners, Inc. 1996 Stock
            Option Plan ********

      11.1  Earnings Per Share *

      27    Financial Data Schedule *

      99.1  Press Release issued by Radiologix, Inc. on September 24, 1999
            announcing its change of corporate name from American Physician
            Partners, Inc. **********

      99.2  Certificate of Ownership and Merger of Radiologix, Inc. with and
            into American Physician Partners, Inc. **********
</TABLE>

--------------
*          Filed herewith.

**         Incorporated by reference to the corresponding Exhibit number to the
           registrant's Registration Statement No. 333-31611 on Form S-4.

***        Incorporated by reference to the corresponding Exhibit number to the
           registrant's Registration Statement No. 333-30205 on Form S-1.

****       Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 10-Q filed on May 15, 1998.

*****      Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 10-Q filed on August 14, 1998.

******     Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 10-Q filed on November 13, 1998.

*******    Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 10-Q filed on May 17, 1999.


                                       21
<PAGE>   24


********   Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 8-K filed on August 3, 1999.

*********  Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 10-Q filed on August 16, 1999

********** Incorporated by reference to the corresponding Exhibit number to the
           registrant's Form 8-K filed on September 24, 1999.


                                       22