Exhibit 10.15


July 21, 1998



Ronald G. Evens, M.D.
Mallinckrodt Institute of Radiology
510 South Kingshighway
St. Louis, MO  63110

Dear Dr. Evens:

This letter agreement, which supersedes all other agreements and
renewals thereto on this subject is for the purpose of stating the
terms and conditions under which you agree to serve Mallinckrodt
Inc., a Delaware corporation, (hereinafter MALLINCKRODT) in a
consulting capacity.

You agree to serve MALLINCKRODT in a consulting capacity during the
period commencing on August 1, 1998 and ending on December 31, 1999.
It is understood that you may terminate this Agreement at any time
upon thirty (30) days written notice to MALLINCKRODT and that
MALLINCKRODT may terminate this Agreement on ninety (90) days written
notice to you.

During the consulting period you shall serve as an advisor to
MALLINCKRODT and in that capacity you will review and evaluate the
research and development programs and plans of MALLINCKRODT and
provide such other advice and assistance in your general areas of
expertise as may be requested from time to time.  It is understood
and agreed that during the consulting period you will devote two (2)
four (4) hour days each month and such additional hours as may be
mutually agreed upon to the services of MALLINCKRODT.

As consideration for your services hereunder, MALLINCKRODT agrees to
pay you as follows:

     During the period August 1, 1998 through December 31,1999, at an
     annual rate of Forty Thousand Eight Dollars ($40,008.00) in
     twelve (12) monthly installments of Three Thousand Three Hundred
     Thirty-Four Dollars ($3,334.00) each.

It is understood that MALLINCKRODT may designate places and locations
where you will provide your services in a consulting capacity and
where this requires you to travel away from St. Louis, Missouri,
MALLINCKRODT will reimburse you for the reasonable travel and living
expenses incurred by you upon submission by you and approval by
MALLINCKRODT of an itemized account of the expenses for which you
seek reimbursement.

You agree to maintain in confidence and not use except for purposes
of this consulting agreement any confidential information of a
business as well as of a technical nature, disclosed to you by
MALLINCKRODT or developed by you as a result of your services to
MALLINCKRODT hereunder.  Upon termination of this Agreement or any
extensions thereof or at any other time that MALLINCKRODT so
requests, you also agree to transmit to MALLINCKRODT any written,
printed or other materials embodying such confidential information
including any copies or excerpts thereof given to you or prepared by
you in connection with your consulting services for MALLINCKRODT.  It
is understood and agreed that this obligation of confidentiality and
non-use shall continue at all times beyond the consulting period and
any extensions thereof.  This obligation of confidentiality and non-
use shall not apply to information which (1) is or later becomes
publicly known under circumstances involving no breach of this
Agreement by you; (2) was already known to you at the time of receipt
of such information from MALLINCKRODT; or (3) is legally made
available to you by a third party.  Your obligations of
confidentiality and non-use shall survive the expiration or
termination of this Agreement.

You agree that during the consulting period you will not enter into
any other consulting agreement in the radiopharmaceutical and
contrast media fields without the prior written consent of
MALLINCKRODT which consent shall not be unreasonably withheld.

It is understood and agreed that any and all inventions and
discoveries whether or not patentable which you conceive and/or make
within the consulting period and any extensions thereof and which
result from information received from MALLINCKRODT or are developed
by you pursuant to your services for MALLINCKRODT shall be the sole
and exclusive property of MALLINCKRODT and that you will upon request
by MALLINCKRODT promptly execute any and all applications,
assignments or other instruments which MALLINCKRODT shall deem
necessary or useful in order to apply for and obtain Letters Patent
in the United States and all other countries for said inventions and
discoveries and in order to assign and convey to MALLINCKRODT the
sole and exclusive right, title and interest in and to said
inventions, discoveries, patent applications and patents thereon.  It
is understood that MALLINCKRODT will bear the cost of preparation of
all such patent applications and assignments and the cost of the
prosecution of all such patent applications in the United States
Patent Office and the patent offices of other countries.

If the foregoing meets with your understanding and approval, please
so indicate by executing this letter in duplicate at the place
indicated below and returning one of the signed duplicates to me.

Very truly yours,                          ACCEPTED & AGREED TO:

MALLINCKRODT INC.                          RONALD G. EVENS, M.D.


By: /s/ C. R. Holman                       /s/ Ronald G. Evens, M.D.
    ------------------------------------   -------------------------
    C.R. Holman, Chief Executive Officer   Dated:  August 4, 1998