Exhibit 3.58
                                     BY-LAWS

                                       OF

                   COMPREHENSIVE MEDICAL IMAGING-FAIRFAX, INC.

                                   ARTICLE I

                                     OFFICES

            SECTION 1. REGISTERED OFFICE -- The registered office of
Comprehensive Medical Imaging-Fairfax, Inc. (the "Corporation") shall be
established and maintained at the office of Corporation Service Company, 2711
Centerville Road, Suite 400, City of Wilmington, County of New Castle, State of
Delaware, and said Corporation Service Company shall be the registered agent of
the Corporation in charge thereof.

            SECTION 2. OTHER OFFICES -- The Corporation may have other offices,
either within or without the State of Delaware, at such place or places as the
Board of Directors may from time to time select or the business of the
Corporation may require.

                                   ARTICLE II

                            MEETINGS OF STOCKHOLDERS

            SECTION 1. ANNUAL MEETINGS -- Annual meetings of stockholders for
the election of directors, and for such other business as may be stated in the
notice of the meeting, shall be held at such place, either within or without the
State of Delaware, and at such time and date as the Board of Directors, by
resolution, shall determine and as set forth in the notice of the meeting. If
the Board of Directors fails so to determine the time, date and place of
meeting, the annual meeting of stockholders shall be held at the registered
office of the Corporation on the first Tuesday in April. If the date of the
annual meeting shall fall upon a legal holiday, the meeting shall be held on the
next succeeding business day. At each annual meeting, the stockholders entitled
to vote shall elect a Board of Directors and they may transact such other
corporate business as shall be stated in the notice of the meeting.

            SECTION 2. SPECIAL MEETINGS -- Special meetings of the stockholders
for any purpose or purposes may be called by the Chairman, the President or the
Secretary, or by resolution of the Board of Directors.

            SECTION 3. VOTING -- Each stockholder entitled to vote in accordance
with the terms of the Certificate of Incorporation of the Corporation and these
By-Laws may vote in person or by proxy, but no proxy shall be voted after three
years from its date unless such proxy provides for a longer period. All
elections for directors shall be decided by plurality vote; all other questions
shall be decided by majority vote except as otherwise provided by the
Certificate of Incorporation or the laws of the State of Delaware.

            A complete list of the stockholders entitled to vote at the meeting,
arranged in alphabetical order, with the address of each, and the number of
shares held by each, shall be open



to the examination of any stockholder, for any purpose germane to the meeting,
during ordinary business hours, for a period of at least ten days prior to the
meeting, either at a place within the city where the meeting is to be held,
which place shall be specified in the notice of the meeting, or, if not so
specified, at the place where the meeting is to be held. The list shall also be
produced and kept at the time and place of the meeting during the whole time
thereof, and may be inspected by any stockholder who is entitled to be present.

            SECTION 4. QUORUM -- Except as otherwise required by law, by the
Certificate of Incorporation of the Corporation or by these By-Laws, the
presence, in person or by proxy, of stockholders holding shares constituting a
majority of the voting power of the Corporation shall constitute a quorum at all
meetings of the stockholders. In case a quorum shall not be present at any
meeting, a majority in interest of the stockholders entitled to vote thereat,
present in person or by proxy, shall have the power to adjourn the meeting from
time to time, without notice other than announcement at the meeting, until the
requisite amount of stock entitled to vote shall be present. At any such
adjourned meeting at which the requisite amount of stock entitled to vote shall
be represented, any business may be transacted that might have been transacted
at the meeting as originally noticed; but only those stockholders entitled to
vote at the meeting as originally noticed shall be entitled to vote at any
adjournment or adjournments thereof.

            SECTION 5. NOTICE OF MEETINGS -- Written notice, stating the place,
date and time of the meeting, and the general nature of the business to be
considered, shall be given to each stockholder entitled to vote thereat, at his
or her address as it appears on the records of the Corporation, not less than
ten nor more than sixty days before the date of the meeting. No business other
than that stated in the notice shall be transacted at any meeting without the
unanimous consent of all the stockholders entitled to vote thereat.

            SECTION 6. ACTION WITHOUT MEETING -- Unless otherwise provided by
the Certificate of Incorporation of the Corporation, any action required or
permitted to be taken at any annual or special meeting of stockholders may be
taken without a meeting, without prior notice and without a vote, if a consent
in writing, setting forth the action so taken, shall be signed by the holders of
outstanding stock having not less than the minimum number of votes that would be
necessary to authorize or take such action at a meeting at which all shares
entitled to vote thereon were present and voted. Prompt notice of the taking of
the corporate action without a meeting by less than unanimous written consent
shall be given to those stockholders who have not consented in writing.

                                  ARTICLE III

                                    DIRECTORS

            SECTION 1. NUMBER AND TERM -- The business and affairs of the
Corporation shall be managed under the direction of a Board of Directors which
shall consist of not less than one person. The exact number of directors shall
initially be one and may thereafter be fixed from time to time by the Board of
Directors. Directors shall be elected at the annual meeting of stockholders and
each director shall be elected to serve until his or her successor shall be
elected and shall qualify. A director need not be a stockholder.

                                       2


            SECTION 2. RESIGNATIONS -- Any director may resign at any time. Such
resignation shall be made in writing, and shall take effect at the time
specified therein, and if no time be specified, at the time of its receipt by
the Chairman, the President or the Secretary. The acceptance of a resignation
shall not be necessary to make it effective.

            SECTION 3. VACANCIES -- If the office of any director becomes
vacant, the remaining directors in the office, though less than a quorum, by a
majority vote, may appoint any qualified person to fill such vacancy, who shall
hold office for the unexpired term and until his or her successor shall be duly
chosen. If the office of any director becomes vacant and there are no remaining
directors, the stockholders, by the affirmative vote of the holders of shares
constituting a majority of the voting power of the Corporation, at a special
meeting called for such purpose, may appoint any qualified person to fill such
vacancy.

            SECTION 4. REMOVAL -- Except as hereinafter provided, any director
or directors may be removed either for or without cause at any time by the
affirmative vote of the holders of a majority of the voting power entitled to
vote for the election of directors, at an annual meeting or a special meeting
called for the purpose, and the vacancy thus created may be filled, at such
meeting, by the affirmative vote of holders of shares constituting a majority of
the voting power of the Corporation.

            SECTION 5. COMMITTEES -- The Board of Directors may, by resolution
or resolutions passed by a majority of the whole Board of Directors, designate
one or more committees, each committee to consist of one or more directors of
the Corporation.

            Any such committee, to the extent provided in the resolution of the
Board of Directors, or in these By-Laws, shall have and may exercise all the
powers and authority of the Board of Directors in the management of the business
and affairs of the Corporation.

            SECTION 6. MEETINGS -- The newly elected directors may hold their
first meeting for the purpose of organization and the transaction of business,
if a quorum be present, immediately after the annual meeting of the
stockholders; or the time and place of such meeting may be fixed by consent of
all the Directors.

            Regular meetings of the Board of Directors may be held without
notice at such places and times as shall be determined from time to time by
resolution of the Board of Directors.

            Special meetings of the Board of Directors may be called by the
Chairman or the President, or by the Secretary on the written request of any
director, on at least one day's notice to each director (except that notice to
any director may be waived in writing by such director) and shall be held at
such place or places as may be determined by the Board of Directors, or as shall
be stated in the call of the meeting.

            Unless otherwise restricted by the Certificate of Incorporation of
the Corporation or these By-Laws, members of the Board of Directors, or any
committee designated by the Board of Directors, may participate in any meeting
of the Board of Directors or any committee thereof by means of a conference
telephone or similar communications equipment by means of which all

                                       3


persons participating in the meeting can hear each other, and such participation
in a meeting shall constitute presence in person at the meeting.

            SECTION 7. QUORUM -- A majority of the Directors shall constitute a
quorum for the transaction of business. If at any meeting of the Board of
Directors there shall be less than a quorum present, a majority of those present
may adjourn the meeting from time to time until a quorum is obtained, and no
further notice thereof need be given other than by announcement at the meeting
which shall be so adjourned. The vote of the majority of the Directors present
at a meeting at which a quorum is present shall be the act of the Board of
Directors unless the Certificate of Incorporation of the Corporation or these
By-Laws shall require the vote of a greater number.

            SECTION 8. COMPENSATION -- Directors shall not receive any stated
salary for their services as directors or as members of committees, but by
resolution of the Board of Directors a fixed fee and expenses of attendance may
be allowed for attendance at each meeting. Nothing herein contained shall be
construed to preclude any director from serving the Corporation in any other
capacity as an officer, agent or otherwise, and receiving compensation therefor.

            SECTION 9. ACTION WITHOUT MEETING -- Any action required or
permitted to be taken at any meeting of the Board of Directors or of any
committee thereof may be taken without a meeting if a written consent thereto is
signed by all members of the Board of Directors or of such committee, as the
case may be, and such written consent is filed with the minutes of proceedings
of the Board of Directors or such committee.

                                   ARTICLE IV

                                    OFFICERS

            SECTION 1. OFFICERS -- The officers of the Corporation shall be a
Chairman, a President, one or more Vice Presidents, a Treasurer and a Secretary,
all of whom shall be elected by the Board of Directors and shall hold office
until their successors are duly elected and qualified. In addition, the Board of
Directors may elect such Assistant Secretaries and Assistant Treasurers as they
may deem proper. The Board of Directors may appoint such other officers and
agents as it may deem advisable, who shall hold their offices for such terms and
shall exercise such powers and perform such duties as shall be determined from
time to time by the Board of Directors.

            SECTION 2. CHAIRMAN -- The Chairman shall be the Chief Executive
Officer of the Corporation. The Chairman shall have the power to execute bonds,
mortgages and other contracts on behalf of the Corporation.

            SECTION 3. PRESIDENT -- The President shall be the Chief Operating
Officer of the Corporation. He or she shall have the general powers and duties
of supervision and management usually vested in the office of President of a
corporation. The President shall have the power to execute bonds, mortgages and
other contracts on behalf of the Corporation.

                                       4


            SECTION 4. VICE PRESIDENTS -- Each Vice President shall have such
powers and shall perform such duties as shall be assigned to him or her by the
Board of Directors.

            SECTION 5. TREASURER -- The Treasurer shall be the Chief Financial
Officer of the Corporation. He or she shall have the custody of the Corporate
funds and securities and shall keep full and accurate account of receipts and
disbursements in books belonging to the Corporation. He or she shall deposit all
moneys and other valuables in the name and to the credit of the Corporation in
such deposit and as may be designated by the Board of Directors. He or she shall
disburse the funds of the Corporation as may be ordered by the Board of
Directors, the Chairman, or the President, taking proper vouchers for such
disbursements. He or she shall render to the Chairman, the President and Board
of Directors at the regular meetings of the Board of Directors, or whenever they
may request it, an account of all his or her transactions as Treasurer and of
the financial condition of the Corporation. If required by the Board of
Directors, he or she shall give the Corporation a bond for the faithful
discharge of his or her duties in such amount and with such surety as the Board
of Directors shall prescribe.

            SECTION 6. SECRETARY -- The Secretary shall give, or cause to be
given, notice of all meetings of stockholders and of the Board of Directors and
all other notices required by law or by these By-Laws, and in case of his or her
absence or refusal or neglect so to do, any such notice may be given by any
person thereunto directed by the Chairman or the President, or by the Board of
Directors, upon whose request the meeting is called as provided in these
By-Laws. He or she shall record all the proceedings of the meetings of the Board
of Directors, any committees thereof and the stockholders of the Corporation in
a book to be kept for that purpose, and shall perform such other duties as may
be assigned to him or her by the Board of Directors, the Chairman or the
President.

            SECTION 7. ASSISTANT TREASURERS AND ASSISTANT SECRETARIES --
Assistant Treasurers and Assistant Secretaries, if any, shall be elected and
shall have such powers and shall perform such duties as shall be assigned to
them, respectively, by the Board of Directors.

                                   ARTICLE V

                                  MISCELLANEOUS

            SECTION 1. CERTIFICATES OF STOCK -- A certificate of stock shall be
issued to each stockholder certifying the number of shares owned by such
stockholder in the Corporation. Certificates of stock of the Corporation shall
be of such form and device as the Board of Directors may from time to time
determine.

            SECTION 2. LOST CERTIFICATES -- A new certificate of stock may be
issued in the place of any certificate theretofore issued by the Corporation,
alleged to have been lost or destroyed, and the Board of Directors may, in its
discretion, require the owner of the lost or destroyed certificate, or such
owner's legal representatives, to give the Corporation a bond, in such sum as
they may direct, not exceeding double the value of the stock, to indemnify the

                                       5

Corporation  against  any claim  that  maybe  made  against it on account of the
alleged  loss  of  any  such  certificate,  or the  issuance  of  any  such  new
certificate.

            SECTION 3. TRANSFER OF SHARES -- The shares of stock of the
Corporation shall be transferable only upon its books by the holders thereof in
person or by their duly authorized attorneys or legal representatives, and upon
such transfer the old certificates shall be surrendered to the Corporation by
the delivery thereof to the person in charge of the stock and transfer books and
ledgers, or to such other person as the Board of Directors may designate, by
whom they shall be cancelled, and new certificates shall thereupon be issued. A
record shall be made of each transfer and whenever a transfer shall be made for
collateral security, and not absolutely, it shall be so expressed in the entry
of the transfer.

            SECTION 4. STOCKHOLDERS RECORD DATE -- In order that the Corporation
may determine the stockholders entitled to notice of or to vote at any meeting
of stockholders or any adjournment thereof, or to express consent to corporate
action in writing without a meeting, or entitled to receive payment of any
dividend or other distribution or allotment of any rights, or entitled to
exercise any rights in respect of any change, conversion or exchange of stock or
for the purpose of any other lawful action, the Board of Directors may fix a
record date, which record date shall not precede the date upon which the
resolution fixing the record date is adopted by the Board of Directors and which
record date: (1) in the case of determination of stockholders entitled to vote
at any meeting of stockholders or adjournment thereof, shall, unless otherwise
required by law, not be more than sixty nor less than ten days before the date
of such meeting; (2) in the case of determination of stockholders entitled to
express consent to corporate action in writing without a meeting, shall not be
more than ten days from the date upon which the resolution fixing the record
date is adopted by the Board of Directors; and (3) in the case of any other
action, shall not be more than sixty days prior to such other action. If no
record date is fixed: (1) the record date for determining stockholders entitled
to notice of or to vote at a meeting of stockholders shall be at the close of
business on the day next preceding the day on which notice is given, or, if
notice is waived, at the close of business on the day next preceding the day on
which the meeting is held; (2) the record date for determining stockholders
entitled to express consent to corporate action in writing without a meeting
when no prior action of the Board of Directors is required by law, shall be the
first day on which a signed written consent setting forth the action taken or
proposed to be taken is delivered to the Corporation in accordance with
applicable law, or, if prior action by the Board of Directors is required by
law, shall be at the close of business on the day on which the Board of
Directors adopts the resolution taking such prior action; and (3) the record
date for determining stockholders for any other purpose shall be at the close of
business on the day on which the Board of Directors adopts the resolution
relating thereto. A determination of stockholders of record entitled to notice
of or to vote at a meeting of stockholders shall apply to any adjournment of the
meeting; provided, however, that the Board of Directors may fix a new record
date for the adjourned meeting.

            SECTION 5. DIVIDENDS -- Subject to the provisions of the Certificate
of Incorporation of the Corporation, the Board of Directors may, out of funds
legally available therefor at any regular or special meeting, declare dividends
upon stock of the Corporation as and when they deem appropriate. Before
declaring any dividend there may be set apart out of any funds of the
Corporation available for dividends, such sum or sums as the Board of Directors

                                       6


from time to time in their discretion deem proper for working capital or as a
reserve fund to meet contingencies or for equalizing dividends or for such other
purposes as the Board of Directors shall deem conducive to the interests of the
Corporation.

            SECTION 6. FISCAL YEAR -- The fiscal year of the Corporation shall
be determined by resolution of the Board of Directors.

            SECTION 7. CHECKS -- All checks, drafts or other orders for the
payment of money, notes or other evidences of indebtedness issued in the name of
the Corporation shall be signed by such officer or officers, or agent or agents,
of the Corporation, and in such manner as shall be determined from time to time
by resolution of the Board of Directors.

            SECTION 8. NOTICE AND WAIVER OF NOTICE -- Whenever any notice is
required to be given under these By-Laws, personal notice is not required unless
expressly so stated, and any notice so required shall be deemed to be sufficient
if given by depositing the same in the United States mail, postage prepaid,
addressed to the person entitled thereto at his or her address as it appears on
the records of the Corporation, and such notice shall be deemed to have been
given on the day of such mailing. Stockholders not entitled to vote shall not be
entitled to receive notice of any meetings except as otherwise provided by law.
Whenever any notice is required to be given under the provisions of any law, or
under the provisions of the Certificate of Incorporation of the Corporation or
of these By-Laws, a waiver thereof, in writing and signed by the person or
persons entitled to said notice, whether before or after the time stated
therein, shall be deemed equivalent to such required notice.

                                   ARTICLE VI

                                   AMENDMENTS

            These By-Laws may be altered, amended or repealed at any annual
meeting of the stockholders (or at any special meeting thereof if notice of such
proposed alteration, amendment or repeal to be considered is contained in the
notice of such special meeting) by the affirmative vote of the holders of shares
constituting a majority of the voting power of the Corporation. Except as
otherwise provided in the Certificate of Incorporation of the Corporation, the
Board of Directors may by majority vote of those present at any meeting at which
a quorum is present, alter, amend or repeal these By-Laws, or enact such other
By-Laws as in their judgment may be advisable for the regulation and conduct of
the affairs of the Corporation.

                                       7