<PAGE>

                                                           EXHIBIT 10.1

                                  RESEARCH AGREEMENT

     THIS RESEARCH AGREEMENT ("Agreement") is made effective as of October 1,
1998 by and between Photogen, Inc., a Tennessee corporation with offices in
Knoxville, Tennessee (hereinafter referred to as "Sponsor"), and the Center for
Imaging and Pharmaceutical Research ("CIPR") of The General Hospital
Corporation, a Massachusetts corporation (doing business as "Massachusetts
General Hospital"), with offices on Fruit St. in Boston, Massachusetts 02114
(hereinafter collectively referred to as "General") and joined into by each
person engaged by General as an Investigator to the extent indicated in Section
20 of this Agreement.  Sponsor and General are collectively referred to as the
"Parties."

                                     WITNESSETH:

     WHEREAS, the research project contemplated by this Agreement is of mutual
interest and benefit to the Sponsor and General, and will further the
instructional, medical, and research objectives of General and the research and
development objectives of the Sponsor.

     NOW THEREFORE, in consideration of the mutual covenants contained herein,
the Parties hereto agree as follows:

1.   THE PROJECT.  General, through the Principal Investigator (as defined
     below) agrees to use its best efforts to perform in a timely and
     expeditious manner one or more research projects pursuant and limited to
     one or more protocols agreed to between the Parties (the "Project").  The
     first phase of the Project will consist of research pursuant to the terms
     of the protocol dated October 1, 1998 entitled "Combination of Two-Photon
     Excitation Photodynamic Therapy (TPE-PDT) with Advanced Tumor Imaging
     Technology for the Treatment of Lung and Prostate Cancer" between the
     Sponsor and General which has been separately delivered and acknowledged by
     the Parties ("Protocol-1").  Additional phases of the Project will be
     conducted pursuant to mutually agreed upon protocols which shall be subject
     in all respects to this Agreement and shall be designated by consecutive
     numbers (e.g., Protocol-2, Protocol-3, etc.). Revised budgets shall be
     mutually agreed for such additional protocols and shall form the basis for
     an amendment to this Agreement  The Project will be conducted under the
     direction of Gerald L. Wolf, Ph.D., M.D. ("Principal Investigator").
     General shall provide personnel, working under the Principal Investigator's
     supervision, (who, together with the 

                                                                               1

<PAGE>

     Principal Investigator, are referred to as the "Investigators"), 
     facilities, and resources as required to accomplish the work necessary 
     to complete the Project in accordance with Protocol-1 and any subsequent 
     protocols agreed to between the Parties.

2.   TERM.  The term of this Agreement and the Project shall be from October 1,
     1998 through September 30, 2003, unless sooner terminated in accordance
     with the terms hereof.

3.   PAYMENT.  The total cost to the Sponsor for the work described in
     Protocol-1 will not exceed $225,000.  The cost for subsequent work pursuant
     to other protocols will be agreed upon by the Parties.  Payments during the
     first year shall be made to General by the Sponsor according to the
     following schedule:

<TABLE>
<CAPTION>
               Amount         Date
               ------         ----
               <S>       <C>
               $50,000   October 1, 1998
               $50,000   By December 1, 1998
               $50,000   By March 1, 1999
               $74,008   By June 1, 1999
</TABLE>

     Checks shall be made payable to "The General Hospital Corporation" and 
     shall be mailed to the following address:

               Financial Director, Grants and Contracts
               Research Finance
               Massachusetts General Hospital
               Thirteenth Street, Building 149, Suite 1115
               Charlestown, MA 02129

     All funds provided by Sponsor under this Agreement may be used at the
     discretion of General in support of the work for the Project.  Any changes
     to the above payment schedule must be agreed to in writing by the Parties.

                                                                               2

<PAGE>

4.   TERMINATION.  This Agreement and the Project may be terminated as set forth
     below, in which case Sponsor's payment obligations will be adjusted through
     the date of termination:

     a.   In the event that either Party defaults in the due performance of its
          respective obligations under this Agreement, or in the event that any
          representation or warranty by either Party in this Agreement or in the
          documentation or data produced through the Project proves to be
          materially false or misleading, and such default or breach is not
          cured within thirty (30) days after written notice by the other Party,
          then the non-defaulting Party may elect to terminate the Project and
          this Agreement by giving written notice to the defaulting Party, and
          this Agreement shall terminate upon the defaulting Party's receipt of
          said notice.

     b.   General shall promptly advise Sponsor if for any reason Dr. Wolf
          cannot be available as the Principal Investigator.  If the Parties
          cannot agree on a qualified scientist as a replacement, Sponsor may
          terminate the Project and this Agreement on the 30th day after
          delivery of written notice to General.

     c.   Notwithstanding anything in this Agreement to the contrary, either
          Party may terminate this Agreement, with or without cause and without
          liability, on 90 days' prior written notice to the other Party; in
          which event this Agreement and the Project shall terminate on the 90th
          day after delivery of such notice. In the event of such termination,
          Sponsor shall have an obligation to continue for up to four (4) months
          beyond such written notification, salary support at the pretermination
          level of all Ph.D. or M.D. personnel who have been committed to the
          Project on half-time or greater basis, provided General uses
          reasonable efforts to reduce such costs to Sponsor.

     d.   The Parties recognize that the results of any particular research
          project cannot be guaranteed even through the use of General's best
          efforts; therefore, it is specifically agreed that the failure of
          General to achieve specific research results or to reach specific
          research milestones shall not constitute a default or breach of this
          Agreement.  Further, the Parties agree that obligations under Sections
          5, 6, 7, 9, 10, 12, 13, 14 and 19 survive any termination of this
          Agreement or the Project.

                                                                              3

<PAGE>

5.   EQUIPMENT.  Title to any equipment purchased or manufactured by General in
     the course of the research conducted under this Agreement or with the use
     of funds provided by Sponsor shall vest in General.

6.   PROPRIETARY INFORMATION OF THE PARTIES.

     a.   General and Sponsor recognize that the conduct of the Project may
          involve the exchange and/or development or discovery of proprietary
          information, including Inventions (as defined in Section 13.a below)
          and other confidential business, technical and scientific information
          or Trade Secrets (defined below).  Accordingly, it is agreed that each
          Party shall use reasonable efforts, no less than those used for its
          own information of similar nature, to retain in confidence all
          proprietary information of the other Party identified as confidential
          at the time of disclosure  and not disclose such information to any
          other person or entity, nor use such information without written
          permission of the Party owning such information, except in accordance
          with the terms of this Agreement. The obligations of this paragraph
          shall be binding upon the parties for a period of 5 years from the
          Effective Date of this Agreement.

     b.   The term "proprietary information" as used herein shall not include
          any information which the recipient clearly shows by appropriate
          documentation:

          (1)  Was at the time of receipt both lawfully and independently known
               to the receiving Party, its agents, or employees;

          (2)  Without breach of this Agreement by the receiving Party has been
               published or is otherwise within the public knowledge or is
               generally known to the public at the time of disclosure;

          (3)  Becomes known or available to the receiving Party without
               restriction from a source other than the disclosing Party,
               provided that such source has an unqualified right to disclose
               such information without restriction;

          (4)  Becomes a part of the public domain after disclosure without
               breach of this Agreement by the receiving Party; or

                                                                              4

<PAGE>

          (5)  Is required by law to be disclosed, in which case the receiving
               Party will give the disclosing Party prompt written notice of the
               required disclosure.  The disclosing Party may, in good faith and
               at its own expense, contest disclosure or seek confidential
               treatment and the receiving Party shall cooperate with the
               disclosing Party in all reasonable respects.

7.   PUBLICATION.

     a.   The Project studies may be worthy of written or oral publication in
          scholarly journals or at meetings.  Such presentation or publication
          shall be jointly authored by the Principal Investigator and Sponsor's
          scientists in accordance with their respective scientific
          contributions to the Project, if applicable (otherwise, by the
          originating person).  Prior to publication, each Party will give the
          other the opportunity to review and comment on any intended public
          disclosure covering the Project, but in no event shall publication be
          permitted without the express written approval of the Party from which
          the results originated in accordance with prevailing academic
          practice.

     b.   In order to give Sponsor an opportunity to protect against loss of
          confidentiality or patent rights as a result of publication, the
          Principal Investigator and/or General shall submit copies of drafts of
          any article, abstract or presentation on the research conducted in the
          Project written by any Investigator to Sponsor for review and comment
          at least thirty (30) days prior to the anticipated date of submission
          for publication or presentation.  In the absence of Sponsor's notice
          to the contrary, General shall be free to submit such drafts for
          publication or presentation. If Sponsor notifies General in writing
          within such 30 day period that it needs additional time to seek patent
          protection for the information, then General and the Investigators, as
          the case may be, agree to defer the submission for publication until
          such patent application has been filed, or an additional 60 days,
          whichever is sooner.  The person seeking to publish the material shall
          make appropriate changes in such material to reflect the Parties'
          reasonable comments concerning patent protection and non-disclosure of
          Sponsor's Trade Secrets (defined below).

                                                                              5

<PAGE>

8.   INDEPENDENT CONTRACTOR.  The Parties' relationship to one another in the
     performance of this Agreement is  that of independent contractors.  The
     Parties are not employees or agents of one another.  Neither Party shall
     have the authority to bind or incur liability for the other except as may
     be expressly authorized in writing.

9.   INDEMNIFICATION.

     a.   Sponsor shall be responsible and shall hold General harmless for any
          injury to persons or damage to property to the extent that such injury
          or damage is caused by the negligence or willful misconduct of
          Sponsor, its employees or staff in carrying out the Project. Sponsor
          will defend, indemnify, and hold harmless General and its trustees,
          employees and staff against any and all actions, suits, claims,
          demands or prosecutions that may be brought or instituted against
          General and/or its trustees, employees and staff based on or arising
          out of the manufacture, use, sale or other distribution of any product
          of Sponsor (or its affiliates or licensees) resulting from the
          Project, except to the extent any such action, suit, claim, demand or
          prosecution is based on the negligence or willful misconduct of
          General and/or its trustees, employees or staff.

     b.   General will defend, indemnify and hold harmless Sponsor and its
          directors, employees and representatives from and against all actions,
          suits, claims, demands or prosecutions that may be brought or
          instituted against any of them to the extent based on the negligence
          or willful misconduct of General and/or its trustees, employees or
          staff.

10.  NEGATION OF WARRANTIES BY GENERAL. Although General will use its best
     efforts in connection with the Project as set forth in Section 1 of this
     Agreement, General makes no warranties, either expressed or implied, as to
     the result of such research or the merchantability or fitness for a
     particular purpose of the research or any product arising out of the
     Project.  General shall not be liable for any direct, consequential, or
     other damages suffered by the Sponsor or others which may result from the
     use of any product arising out of the Project (except to the extent set
     forth in Section 9, above).

                                                                              6

<PAGE>

11.  KEY PERSONNEL.  Gerald L. Wolf, Ph.D., M.D., Principal Investigator, is
     considered to be essential to the Project.  Substitutions for or
     substantial changes in his level effort or participation will not be made
     without the prior written approval of Sponsor.  Each Party will obtain
     agreements from those of its employees, independent contractors,
     consultants and similar persons involved in the Project (in the case of
     General, all Investigators) causing such third parties to be bound by the
     provisions of Sections 6, 7, 12 and 13 hereof.

12.  INTELLECTUAL PROPERTY RIGHTS OF THE PARTIES.  Neither Party shall have any
     claim by virtue of this Agreement or the Project to any right, title or
     interest in any Invention, Trade Secret or Patent Rights (defined below) or
     any other intellectual property rights (a) issued to, owned or controlled
     by the other Party prior to the date hereof, or (b) after the date hereof
     except any new Inventions, Trade Secrets or Patent Rights conceived and
     reduced to practice, constructively or actually in the performance of the
     Project and as specifically set forth in Section 13 below.

13.  INVENTIONS AND PATENT RIGHTS.

     a.   The term "Invention" means a patentable discovery or invention
          conceived and reduced to practice, constructively or actually in the
          performance of the Project, including any novel process, method,
          formula, machine, manufacture, composition of matter and technology.
          The term "Sponsor Trade Secret" means non-patented know-how,
          compositions, protocols, formulas, processes and techniques,
          discoveries, machines, ideas, compilations of information, computer
          programs (including software and data used in all such programs),
          drawings, specifications and technical information owned or developed
          by Sponsor or its employees.  The term "Patent Rights" means patent
          applications and patent disclosures claiming an Invention, together
          with all letters patent, reissuances, continuations, divisionals,
          those claims in any continuations-in-part of any patent application
          which claim an Invention described in said patent application,
          revisions, extensions, and reexaminations thereof.

     b.   Inventions, Patent Rights and Sponsor Trade Secrets arising out of
          the Project during the term of this Agreement and for a period of 12
          months thereafter shall be owned as follows:

                                                                              7

<PAGE>

          (1)  General will own all such Inventions it, the Principal
               Investigator or any other General Investigator independently
               conceives (a "General Invention") and all corresponding Patent
               Rights, subject to the license if Sponsor exercises its option
               described in paragraph 13.f below;

          (2)  General and Sponsor will jointly own all such Inventions jointly
               conceived by General, the Principal Investigator or any other
               Investigator together with Sponsor (a "Joint Invention") and all
               corresponding Patent Rights, subject to the license if Sponsor
               exercises its option described in paragraph 13.f below; and

          (3)  Sponsor will own all Inventions and Sponsor Trade Secrets Sponsor
               independently conceives or owns and all corresponding Patent
               Rights.

     c.   With respect to General Inventions, General will use reasonable
          efforts, consistent with the practices of the Office of Technology
          Affairs to cause all Investigators to report such Invention and assign
          all of their right, title and interest therein to General; and with
          respect to Joint Inventions, the Sponsor will cause its personnel and
          General will use reasonable efforts to cause each Investigator to
          report such Invention and assign all of their right, title and
          interest therein to Sponsor and General jointly.  Sponsor and General
          shall promptly advise the other in writing of each General Invention
          or Joint Invention and shall cause their Investigators and personnel,
          as applicable, to maintain current and reasonably detailed records (in
          accordance with customary academic research practice) as to possible
          General and Joint Inventions, which shall be open to inspection by the
          other Party with reasonable advance notice.  The Parties shall discuss
          for up to 90 days after the date an Invention is disclosed by one
          Party to the other Party whether patent applications pertaining to
          such General or Joint Invention should be filed and in which
          countries.  All of the foregoing shall constitute proprietary
          information subject to Section 6, above.

     d.   If both Parties agree that patent applications should be filed, patent
          applications relating to General Inventions shall be filed by General
          and patent applications relating to Joint Inventions shall be filed as
          agreed by the Parties.  If within such 90-day period one Party states
          in writing that it 

                                                                              8

<PAGE>

          is not interested in filing patent applications on either a General 
          Invention or a Joint Invention (a "declining Party") and the other 
          Party (a "prosecuting Party") is interested in filing such 
          applications, the prosecuting Party shall be free, at its own 
          expense, to file such applications in the name(s) of the parties to 
          whom the Inventors would be obliged to assign and the declining 
          Party shall render the prosecuting party, at the prosecuting 
          Party's expense, all necessary assistance in order to facilitate 
          filing of such Joint Inventions..  All prosecution costs pertaining 
          to patent applications covering a General or Joint Invention that 
          are filed by mutual agreement of the Parties (including 
          preparation, filing, prosecution, issuance and maintenance costs) 
          shall be borne by Sponsor. General shall select counsel for such 
          General or Joint Inventions, subject to the approval of the 
          Sponsor, which approval shall not be unreasonably withheld. General 
          agrees to cause Patent counsel selected by it to promptly provide 
          Sponsor with copies of all documents relating to the patent 
          application, to be available to Sponsor for consultation and 
          suggestions and for Sponsor to be otherwise fully informed 
          regarding all matters relating to the patent application and its 
          prosecution.

     e.   The Parties agree to cooperate and work together in good faith to
          effect the provisions of this Section 13.  Each Party agrees to
          execute and deliver (or cause to be executed and delivered) all
          assignments and other instruments of transfer necessary to effect the
          provisions of this Section 13.

     f.   As to all Patent Rights relating to a General Invention or a Joint
          Invention, General hereby grants Sponsor for the twelve (12) months
          next following the first filing of patent applications in any
          jurisdiction relating to such Invention the irrevocable first option
          to obtain a license granting Sponsor the following rights and
          containing the following terms:

          (1)  Sponsor shall for the life of all patent rights, unless sooner
               terminated by either party in accordance with the terms of such a
               license agreement, have a world-wide, exclusive (subject only to
               paragraph (h) below), royalty-bearing license granting Sponsor
               the right to use the Invention, to design, make, have made,
               market lease, offer for sale, sell and/or distribute products
               embodying or produced through the use of the Invention, itself or
               through third parties by way of sublicense, and in all other
               respects to use, sublicense, and commercialize the Invention and
               any such product 

                                                                              9

<PAGE>

               under all Patent Rights.  Pursuant to such license, Sponsor 
               shall use reasonable efforts to commercialize such products in 
               accordance with time limits and objectives consistent with the 
               market potential of the Invention and the capacity and 
               resources of the Sponsor.  Sponsor will be free to design the 
               products, and select pricing and marketing methods in its 
               discretion.

          (2)  Sponsor shall pay General a reasonable royalty of an amount
               equal to the greater of $10,000 per year  or up to 5% of
               Sponsor's annual net sales revenues for such Invention (gross
               revenues actually received by Sponsor from sales of the specific
               product which results from the General or Joint Invention, net of
               customary cash and trade discounts, returns and allowances);
               provided, that Sponsor will pay the minimum $10,000 annual
               royalty beginning in the fifth year after the license is executed
               or sooner if Sponsor has net sales revenues before the fifth
               year. The applicable royalty rate shall be agreed upon by the
               parties within 30 days of Sponsor's exercise of the option.

          (3)  Sponsor will use all reasonable efforts to defend all challenges
               to Patent Rights, including alleged infringements, and General
               will cooperate with Sponsor in that regard.

          (4)  Sponsor may abandon the license at any time by express written
               notice to General, in which case all rights will revert back to
               General and all license and royalty obligations on Sponsor shall
               terminate.

          (5)  Product liability indemnification and insurance requirements
               which are reasonably acceptable to General's liability insurance
               carrier.

          (6)  In addition to the foregoing, any other commercially reasonable
               terms standard for agreements between universities and industry
               not inconsistent with the foregoing.

          Sponsor may exercise this option by giving written notice of exercise
          to General during said twelve-month period.  Thereafter, General and
          Sponsor each agree to negotiate in good faith and to enter into a
          license agreement incorporating the foregoing terms within six (6)
          months after 

                                                                              10

<PAGE>

          notice of exercise.  If Sponsor elects not to give written notice 
          of exercise during such 12-month period, General may grant a 
          license to such Invention and Patent Rights to any other person or 
          entity.

     g.   General represents and warrants to Sponsor that, to the best of its
          knowledge, based on a diligent review of its documents, as of the
          effective date hereof, General is not prohibited or prevented from
          granting such a license to Sponsor.  General agrees, during the term
          of the Project hereunder, not to enter into an agreement with any
          third party to fund Principal Investigator to conduct the Project and
          to use reasonable care not to enter into an agreement with a third
          party under terms that will prevent General from granting to the
          Sponsor the license contemplated under subsection (f) above.  General
          will monitor the activities of the Principal Investigator in order to
          avoid conflicting activities that would prevent General from granting
          such a License.

     h.   It is understood that General will reserve the right to use any
          General Invention or Joint Invention only for research, clinical and
          educational purposes, and that if federal funding supports the
          Invention, Sponsor's license will be subject to the rights, conditions
          and limitations imposed by U.S. law including without limitation the
          royalty-free non-exclusive license granted to the U.S. government (see
          35 USC sec. 202 et. seq. and regulations pertaining thereto). General
          represents, warrants and agrees with Sponsor that no federal funds
          will be used to support the Project as of the date of this Agreement
          and, if any such funds will be used in the future, General will give
          Sponsor at least 120 days' prior written notice of General's
          acceptance of federal funds..

14.  DATA.  The original data generated as a result of the Project shall be
     provided to Sponsor promptly, and Sponsor may use such data as it deems
     advisable, including for purposes of publication, presentation to the
     scientific community, seeking regulatory approvals or for any other
     purposes, except to the extent that such use infringes a patent owned or
     controlled by General not licensed to Sponsor. However, this provision
     shall not be interpreted to restrict General's publication rights under
     Section 7 of this Agreement.  The Principal Investigator shall report to
     the Sponsor every 90 days on the status and results of the Project. The
     Principal Investigator shall keep reasonable and customary records of the
     Project and related data sufficient for Sponsor's regulatory approval
     activities and shall make such records available to Sponsor on reasonable
     request.

                                                                              11

<PAGE>

15.  PUBLICITY.  Neither Party shall use the name of the other Party or of any
     Investigator in any advertising or promotional material without the prior
     written approval of the other Party.  The foregoing notwithstanding, (a)
     General and the Principal Investigator shall acknowledge Sponsor's support
     of the Project in their respective reports and publications, (b) Sponsor
     may disclose the existence and describe the terms of, and may file a copy
     of this Agreement (redacted to the extent Sponsor deems appropriate to
     ensure confidentiality) as an exhibit to its press releases, reports and
     governmental filings, including reports and filings with the U.S.
     Securities and Exchange Commission and relevant foreign government
     authorities; and (c) Sponsor may make reference to technical publications
     by the Principal Investigator or his co-authors.  Any publicity or
     governmental filings of this Agreement pursuant to this Section 15 shall
     describe the relationship of the Parties accurately and appropriately,
     including the fact that CIPR is a division of Massachusetts General
     Hospital and the same are affiliated with Harvard Medical School.

16.  APPROVALS.  General represents and warrants to Sponsor that this Agreement
     and the Project have received the required approvals within Massachusetts
     General Hospital and that no other approvals are required to authorize the
     execution and effectiveness of this Agreement.  Sponsor represents and
     warrants to General that this Agreement and the Project have been approved
     by its Board of Directors.

17.  MODIFICATION.  This Agreement and the Protocol constitute the sole, full,
     and complete agreement by and between the Parties concerning the subject
     matter hereof and supersedes and replaces all prior agreements, discussions
     and representations (including the July 9, 1998 and July 10, 1998
     correspondence between the Parties and the Memorandum of Understanding
     referred to therein).  No amendments of any provision of this Agreement
     shall be valid unless reduced in writing and signed by the Parties and all
     waivers must be in writing and signed by the Party against which the waiver
     is to be enforced.

18.  NOTICES AND OTHER COMMUNICATIONS. With the exception of Sponsor's payments
     under Section 3, all notices and other communications between the Parties
     in connection with this Agreement shall be in writing and deemed
     sufficiently given when delivered by messenger or overnight courier
     providing for receipted delivery, transmitted by fax with confirmation of

                                                                              12

<PAGE>

     transmission or sent by prepaid United States mail or other recognized
     carrier, addressed as follows:

     a.   If to Sponsor:

          John Smolik
          President, CEO
          Photogen, Inc.
          7327 Oak Ridge highway
          Knoxville, TN 37931
          Fax number:  (423) 769-4013

     b.   If to General:

          Director, Office of Technology Affairs
          Massachusetts General Hospital
          13th Street, Building 149
          Suite 1101
          Charleston, MA  02129
          Fax number:  (617) 726-1668

     Either Party may change its address by written notice given to the other
     Party. It is specifically provided that this notice provision shall not be
     construed in such a manner as to abrogate the provisions of Section 16
     regarding modification of this Agreement.

19.  GOVERNING LAW; CHOICE OF FORUM. This Agreement is made and entered into the
     State of Massachusetts and its validity and interpretation and the legal
     relations of the Parties shall be governed by the internal laws of the
     State of Massachusetts without regard to its provisions on conflict of
     laws.  Each Party submits to the exclusive jurisdiction of any state or
     federal court sitting in Chicago, Illinois in any action or proceeding
     relating to this Agreement and each Party agrees that all claims in respect
     of the action or proceeding may be heard and determined only in any such
     court.  Each of such Parties waives any defense of inconvenient forum to
     the maintenance of any action or proceeding so brought and waives any bond,
     surety, or other security that might be required of any other Party with
     respect thereto.

                                                                              13

<PAGE>

20.   INVESTIGATORS JOIN INTO AGREEMENT.  Each person engaged by General as an
     Investigator hereby joins into this Agreement and agrees to become bound to
     all terms applicable to him or her and in particular, Sections as 1, 7(b)
     and 13.

THIS AGREEMENT shall not be considered accepted, approved, or otherwise
effective until the signature of each Party is affixed in the space provided
below.

IN WITNESS WHEREOF, signifying their acceptance of and agreement to be bound by
the terms and conditions of this Agreement, the signatures of the Parties are
affixed hereto:

PHOTOGEN, INC.                     THE GENERAL HOSPITAL CORPORATION,
                                   doing business as MASSACHUSETTS
                                   GENERAL HOSPITAL


By: /s/John Smolik                 By: /s/David J. Glass
    ----------------------             ---------------------
       John Smolik                     David J. Glass, Ph.D.
       President, CEO                  Associate Director for Patents
       Photogen, Inc.                  Office of Technology Affairs



Date: 10/12/98                     Date: 10/6/98
      --------------------               --------------------


                     JOINED INTO BY THE FOLLOWING INVESTIGATORS:

                                   Name(s)

Date:        10/7/98                   Gerald L. Wolf
       -----------------------     --------------------------------
Date:
       -----------------------     --------------------------------
Date:
       -----------------------     --------------------------------