<PAGE>   1
                                                                   Exhibit 10.33





November 21, 2000


Mr. Leon Maraist
Executive Vice President & Chief Operating Officer
250 S. Australian Avenue, 9th Floor
West Palm Beach, Florida 33401

RE:   PROPOSED EMPLOYMENT AGREEMENT

Dear Leon:

US Diagnostic Inc. ("Company") wishes to outline the basic terms of its
understanding with you regarding changes to your employment arrangement.

The following represents an outline of those terms and, by executing a copy of
this letter, you agree that the parties may enter into a separate employment
agreement which would encompass these terms and conditions if so required by the
Company:

1.   TITLE - You will be named to the Board of Directors at the October Board
     meeting and will assume the title of President of the Company on January 5,
     2001.

2.   COMPENSATION - Your current compensation including car allowance and
     benefits will remain the same. You will continue to be eligible for bonuses
     at the discretion of the Company's Board of Directors.

3.   TERM - The term of this arrangement will be one year from the effective
     date of January 5, 2001.

4.   TERMINATION/RETENTION PAYMENT - In the event the Company terminates your
     employment (including the planned one year term), other than for cause as
     defined in your current employment agreement, the Company will pay to you
     an amount equal to six (6) months of your current base compensation of
     $200,000 per year, or a total payment of $100,000. In the event such
     termination is prior to the term, you will be entitled to both the
     termination payment and the remaining balance of your employment agreement
     payable on or before January 5, 2002.

5.   SPECIAL TERMINATION - In the event any entity, other than the Company with
     which USD currently is having discussions, merges with or becomes owner of
     the Company after March 1, 2001, you will be eligible for the provision set
     forth in #4 of this Letter Agreement (Termination/Retention Payment). In
     such event, you will be entitled to both the termination payment and
     remaining balance of your employment regardless of whether or not there is
     an offer of employment.


<PAGE>   2


6.   TRAVEL - You will be entitled to travel first class airfare or business
     trips whenever practical as determined by you.

7.   EXISTING AGREEMENT. The above terms and conditions are not intended to
     alter the current employment agreement that presently exists and all
     obligations the Company presently has as outlined in the Proxy Statement,
     as well as the memorandum to the Board regarding retention bonus payments,
     will not be affected. Your existing employment agreement dated October 20,
     1997 is extended until January 5, 2002, and the provisions of this letter
     agreement are incorporated therein except the following paragraphs of the
     employment agreement are deleted: 3(b), and 5(c).

We look forward to working together with you in completing the strategic plan of
the Company.

Very truly yours,


US DIAGNOSTIC INC.



By: /s/ Joseph A. Paul
   ---------------------
   Joseph A. Paul
   President

AGREED TO AND ACKNOWLEDGED BY:

/s/ Leon Maraist
------------------------
Leon Maraist
Vice President & Chief Operating Officer