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                                                                   EXHIBIT 10.48

                                  November 10, 1998




Mr. Gerard A. Wills
Molecular Biosystems, Inc.
10070 Barnes Canyon Road
San Diego, California  92121

          RE:  TERMS OF SEPARATION FROM MBI

Dear Jerry:

     In accordance with our recent discussions, this letter agreement
("Agreement") will set forth the terms of our agreement regarding your
departure from MBI in conjunction with the Company reorganization.

     1.   DESCRIPTION.  Both parties shall regard your departure as a necessary
          reduction in force related to the present Company restructuring.

     2.   TIMING.  Your separation shall be effective as of the end of the day,
          December 31, 1998 ("Separation Date").  You will be paid all accrued
          and unpaid salary through the Separation Date.  During the time
          between November 10, 1998 and December 31, 1998, you will be
          considered a regular, full-time employee, and will be expected to work
          at least thirty (30) hours per week in order for your normal benefit
          coverage to continue.

     3.   EFFECTIVE DATE.  This Agreement shall become effective on the eighth
          day following your execution of this Agreement, unless you have
          revoked acceptance during the seven days prior thereto.  [SEE
          Paragraph 13(b)].  Regardless of when this takes place, this Agreement
          shall be deemed to have been in effect retroactive to November 13,
          1998.  This Agreement shall not become effective unless executed by
          you and MBI.

     4.   RETENTION BONUS.   In consideration of your cooperation and assistance
          in MBI's recent restructuring, you will be provided with a one-time,
          lump sum retention bonus of fifty thousand dollars ($50,000) payable
          on November 10, 1998.  At your request, MBI will withhold payroll
          taxes at the customary rate utilized for lump-sum bonus payments to
          employees, unless you choose higher withholding rates.

     5.   SEPARATION PAYMENTS.  In consideration of your undertakings in this
          Agreement, MBI shall provide you with severance benefits equivalent to
          approximately ten and one-half (10.5) month's current salary
          ($155,692.31).  This amount shall be paid to you in a lump sum on
          January 4, 1999.  In addition, you will be paid your normal payroll
          checks on November 27, December 11 and December 25, 1998.  Taxes and
          other appropriate deductions will be withheld; however, contributions
          to your 401(k), health care reimbursement account, or any other
          benefit deductions will not be allowed.  Any questions concerning the
          scope of your severance package should be directed to the Human
          Resources Department.

     6.   WELFARE AND OTHER BENEFITS.  Regular medical, dental, vision, as well
          as basic and optional life and accidental death and dismemberment
          insurance will continue through December 31, 1998.  Long-term
          disability coverage will continue through your last day worked. In
          addition:

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Mr. Gerard A. Wills
November 10, 1998
Page 2


          (a)  Medical, dental and vision insurance under MBI's policies for you
               and currently insured dependents will be extended through COBRA
               from January 1, 1999, through November 30, 1999, at MBI's expense
               (unless you obtain other coverage prior to that time, in which
               event you must notify MBI).  Thereafter, you may elect to
               continue COBRA coverage at your expense for an additional seven
               (7) months.  (Maximum COBRA coverage is eighteen (18) months.)

          (b)  You will be provided with the information needed to request the
               option of converting the group life insurance and/or accidental
               death and dismemberment insurance coverage to an individual
               policy.  You will work directly with CIGNA should you elect this
               option.  You will need to exercise this option within thirty-one
               (31) days of the benefits termination date, December 31, 1998.

          (c)  You will be provided with the information needed to request the
               option of converting the Long-Term Disability (LTD) insurance
               coverage to an individual policy.  You should work directly with
               UNUM should you elect this option.  You would need to exercise
               this option within thirty-one (31) days of the Separation Date.

          (d)  Depending upon the amount of your 401(k) plan balance, you may
               either elect to remain in the plan with no further deposits
               (balance greater than $5,000), or elect a distribution of your
               funds (balance less than $5,000).  You will notify CIGNA within
               thirty (30) days of the Separation Date as to how and to whom
               your funds should be distributed.  Information on how to initiate
               your desired option will be provided by Human Resources.

          (e)  If you are a participant in the health care reimbursement plan,
               your will have until March 31, 1999 to request reimbursement for
               charges incurred through the Separation Date.  Any such request
               should be made directly to UNUM.

          (f)  You will be paid for all earned and unused vacation hours on
               January 4, 1999.  You will not accrue any additional vacation
               following the Separation Date.

          (g)  MBI will repurchase from you one thousand eight hundred and
               twenty eight (1828) shares of restricted MBI stock at the price
               of eight dollars and seventy-five cents ($8.75) per share.  This
               repurchase amount ($15,995.00) will be paid to you on November
               10, 1998.

          (h)  Your voicemail and pager service will be continued and paid for
               by MBI through June 30, 1999.  Further, you will be allowed to
               retain your MBI computer equipment (laptop, monitor and keyboard)
               and cellular phone.

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Mr. Gerard A. Wills
November 10, 1998
Page 3


          Representatives of Human Resources will be available to explain
          details of the above items.

     7.   STOCK OPTIONS.

          (a)  CURRENT OPTIONS.  You have been granted stock options as
               described in the attached schedule.  As of November 10, 1998, MBI
               will accelerate the vesting of all unvested options.  MBI will
               also extend the period of exercisability of those options to the
               maximum period available under our plans.  (That is, the lapse
               dates in the charts, which are already at the maximum, will not
               be reduced on account of your ceasing to be an employee).

          (b)  Until June 30, 1999 ("Reporting Period"), you will be under the
               same constraints imposed by MBI and securities laws on MBI vice
               presidents regarding the exercise of options and the purchase and
               sale of MBI shares.  During the Reporting Period, you shall
               notify us of your intentions in this regard (including options
               exercises) and shall execute such forms, if any, as MBI and the
               U.S. securities laws require.  If you wish, you may use the
               services of MBI's Finance Department to assist you in exercising
               your options and selling your shares during the Reporting Period.
               You acknowledge that taxes and commissions will be withheld from
               any profit you make on the sale of stock following exercise and
               sale during the Reporting Period.  During the Reporting Period,
               you will be notified monthly, along with other MBI Section 16(b)
               reporting persons, as to the current trading status of MBI stock
               (i.e., "green light", "yellow light", or "red light").  At no
               time --- presently, or at any future time, during or after the
               Reporting Period --- may you trade on MBI material inside
               information.

          7.   PLACEMENT.  MBI will provide you with six (6) months'
               outplacement counseling and services through Lee Hecht Harrison
               starting January 4, 1999 and running through June 30, 1999.

          8.   COOPERATION; NO RAIDING; NON-DISPARAGEMENT.  You shall cooperate
               with MBI in any and all governmental and/or third party
               proceedings including, but not limited to, lawsuits and other
               disputes.  Following your separation, such cooperation shall be
               at MBI's expense (except that MBI cannot pay for the content of
               sworn testimony).  You shall keep MBI advised of contacts by
               governmental agencies and third parties, and shall reasonably
               cooperate with MBI in handling any response.  At your request,
               MBI shall provide counsel to you, if the parties deem counsel
               necessary or desirable, in any such proceeding. You shall not
               voluntarily cooperate with, testify for, or otherwise assist
               parties adverse to MBI in a dispute, although you may respond to
               compulsory process (i.e., a valid subpoena).

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Mr. Gerard A. Wills
November 10, 1998
Page 4


               For a period of one (1) year following the Separation Date, you
               shall not contact persons employed by MBI at the time to recruit
               them for your business or any business by which you are employed
               or with which you are affiliated, or otherwise encourage them to
               leave MBI.

               You shall not materially disparage MBI, and MBI shall not
               materially disparage you, to any third parties.

          9.   CONTACTS BY POTENTIAL EMPLOYERS.  Potential employers contacting
               MBI will be told only that your separation was as the result of a
               reduction in force (layoff); your title; your dates of
               employment; and your final salary.  MBI will provide you with
               positive references.

          10.  EMPLOYMENT BY COMPETITORS.  This Agreement does not limit your
               ability to work for competitors of MBI, provided that, for a
               period of one (1) year from the Separation Date, reasonably in
               advance of accepting any employment with the company, individual,
               or other entity engaged or planning to engage in the development,
               manufacture, or marketing of ultrasound contrast agents
               ("Competitor"), you shall notify the President or Chief Executive
               Officer of MBI.  Prior to accepting any such employment, or
               promptly following your engagement in any consulting relationship
               with a Competitor, you shall give MBI the opportunity to discuss
               your plans with you in order to explore any possible problems or
               conflicts.  While MBI shall not disparage you or attempt to
               dissuade any Competitor from employing or engaging you, you
               acknowledge that MBI may contact such Competitor informing it
               truthfully of your confidentiality obligations to MBI.  MBI shall
               have no liability to you in the event of a decision by a
               Competitor not to employ or engage you following contact by MBI.
               Failure to provide this notice to MBI during this period shall be
               deemed a material breach of this Agreement.  You remain bound by
               your confidentiality obligations to MBI even if you work for a
               Competitor.

          11.  CONFIDENTIALITY.  You will not remove any MBI information,
               documents, or other property from its premises, and you will
               return any MBI information currently in your possession or
               control off MBI's premises.  In addition:

               (a)  You acknowledge that in the course of your employment with
                    MBI you have had and will have access to and familiarity
                    with information of substantial value to MBI which is not
                    old or generally known to the public and which gives MBI an
                    advantage over its competitors who do not know or use it
                    including, but not limited to, strategies, business plans,
                    research, formulas and formulations, techniques, designs,
                    drawings, processes, inventions, developments, equipment,
                    prototypes, sales and customer information, and financial
                    information, relating to the business, products, and
                    practices of MBI (hereinafter referred to as "Confidential
                    Informa-

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Mr. Gerard A. Wills
November 10, 1998
Page 5


                    tion").  You agree at all times following your
                    termination to regard and preserve as confidential such
                    Confidential Information, and to refrain from publishing
                    or disclosing any part of such Confidential Information
                    and from using it except on behalf of MBI.  You further
                    agree at all times to refrain from any other acts or
                    omissions that would reduce the value of such
                    Confidential Information to MBI and to take all
                    reasonably necessary and desirable precautions to prevent
                    such Confidential Information from being disseminated to
                    any third parties.

               (b)  You acknowledge that a breach of the terms of this paragraph
                    would threaten MBI with immediate and irreparable harm not
                    readily compensable in money damages, and that MBI would be
                    entitled to injunctive and declaratory relief to stop or
                    prevent any such breach.

               Nothing in this paragraph shall be construed to prevent you from
               using or disclosing your general knowledge of the imaging
               industry (as opposed to MBI-specific information) acquired at any
               time prior to or during the course of your employment.

          12.  GENERAL RELEASE.  In consideration for the payments and other
               consideration described in this Agreement, you hereby
               unconditionally, irrevocably, and absolutely release and
               discharge MBI, its employees, officers, directors, agents,
               stockholders, independent contractors, attorneys, consultants,
               predecessors, successors and assigns from any and all claims
               related in any way to any acts, transactions, or occurrences
               between you and MBI to date, including but not limited to all
               losses, liabilities, claims, charges, demands and causes of
               action, known or unknown, suspected or unsuspected, arising
               directly or indirectly out of, or in any way connected with, your
               employment with or termination from MBI. This includes, but is
               not limited to, any claim of employment discrimination arising
               under federal, state or local law, including the Age
               Discrimination in Employment Act of 1967, as amended, the
               Americans with Disabilities Act, the California Fair Employment
               and Housing Act, any other statutory cause of action, and any
               tort or contract claims.

          WAIVER OF ADDITIONAL CLAIMS.  Section 1542 of the Civil Code of the
          State of California provides as follows:

          A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE CREDITOR DOES
          NOT KNOW OR SUSPECT TO EXIST IN HIS FAVOR AT THE TIME OF EXECUTING THE
          RELEASE, WHICH IF KNOWN BY HIM MUST HAVE MATERIALLY AFFECTED HIS
          SETTLEMENT WITH THE DEBTOR.

          You waive and relinquish any right or benefit which you may have under
          this section or any other provision of the statutory or nonstatutory
          law or any other jurisdiction to the full extent that you may lawfully
          waive all such rights and benefits.  In connection with such

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Mr. Gerard A. Wills
November 10, 1998
Page 6


          waiver and relinquishment, you acknowledge that you are aware that
          you, your attorneys or agents may hereafter discover claims or
          facts in addition to or different from those which they now know or
          believe to exist, but that it is your intention thereby fully,
          finally, and forever to release all claims, disputes, and
          differences, known or unknown, suspected or unsuspected, which now
          exist, may exist, or have existed between the parties, their
          employees, agents, assigns, and other privies.  Unless this
          provision shall have been procured by fraud, the releases given
          herein shall be effective regardless of the discovery or existence
          of any such claim or fact.

          13.  ACKNOWLEDGEMENTS.  You hereby further acknowledge and agree as
               follows:

               (a)  NO PRE-EXISTING OBLIGATION.  You acknowledge that but for
                    the entry by you and MBI into this Agreement, you are not
                    entitled to the additional payments and other consideration
                    provided for in these agreements (with the exception of
                    federal rights such as COBRA).

               (b)  TIME FOR REVIEW; EFFECTIVE DATE.  You acknowledge that you
                    have been given twenty-one (21) days to consider the terms
                    of this Agreement.  In addition, both parties acknowledge
                    that you may revoke your acceptance of this Agreement within
                    seven (7) days following your signature (which may occur
                    during the twenty-one (21) day period), and that at your
                    option, you may elect not to use the full twenty-one (21)
                    day period;

               (c)  ADVICE OF COUNSEL AND OTHER PROFESSIONAL ADVISORS.  You
                    acknowledge that you have been advised in writing to consult
                    with an attorney and an accountant or tax advisor before
                    entering into these agreements.  You acknowledge either that
                    you have done so and received counseling to your
                    satisfaction, or that you have declined to do so and
                    voluntarily executed this Agreement without fraud or undue
                    influence.

               (d)  EFFECTIVE DATE.  This Agreement shall not become effective
                    or enforceable until seven (7) days after you sign this
                    Agreement.  In other words, you may revoke your acceptance
                    of this Agreement within seven (7) days after you sign it.
                    Your revocation must be in writing and received by Laura
                    Gross within the seven (7) day period in order to be
                    effective.  If you do not revoke acceptance within the seven
                    (7) day period, Your acceptance of this Letter Agreement
                    shall become binding and enforceable.

          14.  CONSEQUENCES OF BREACH.  If you breach this Agreement, MBI may
               terminate it, cease providing payments and benefits hereunder and
               recover all payments and benefits already paid, in addition to
               any other remedies it may have.

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Mr. Gerard A. Wills
November 10, 1998
Page 7


          15.  OTHER MATTERS.  You will receive materials prepared by Human
               Resources describing various rights and duties, including
               optional benefits, which will come into effect following your
               termination. You will also receive instruments as are customarily
               submitted to terminated employees.  You will cooperate fully in
               these separation meetings and execute or complete such
               instruments at the time of your termination.

          16.  PROHIBITION AGAINST ASSIGNMENT.  You shall not assign this
               Agreement or any of the rights, interests and benefits hereunder.
               However, you may provide for the assignment, gift, bequest, or
               transfer of such benefits under this Agreement to your
               survivor(s), or to a trust for their benefit, on your death, or
               in the event that you suffer a major disability.

          17.  ENTIRE AGREEMENT.  This Agreement between the parties dated
               November 13, 1998, constitutes the entire agreement between the
               parties hereto and contains all of the agreements between the
               parties with respect to its subject matter.  This Agreement
               supersedes any and all other agreements, either oral or in
               writing, between the parties hereto with respect to their subject
               matter.

          18.  BINDING EFFECT.  This Agreement shall be binding upon and inure
               to the benefit of both parties and their respective heirs, legal
               representatives, executors, administrators, and successors.

          19.  GOVERNING LAW.  This Agreement shall be subject to and governed
               by the laws of the State of California irrespective of the fact
               that you may become a resident of a different state.

          20.  AMENDMENT OF AGREEMENT.  No change or modification of this
               Agreement shall be valid unless the same is in writing and signed
               by both parties.  No waiver of any provision of this Agreement
               shall be valid unless in writing and signed by the person or
               party to be charged.

          21.  SEVERABILITY.  If any portion or portions of this Agreement shall
               be, for any reason, deemed to be invalid or unenforceable, the
               remaining portion or portions shall nevertheless be valid,
               enforceable and carried into effect, unless to do so would
               clearly violate the present legal and valid intention of the
               parties hereto.

          22.  HEADINGS.  The headings of this Agreement are inserted for
               convenience only and are not to be considered in construction of
               the provisions hereof.

          23.  WAIVER OF BREACH.  The waiver by either of the parties hereto of
               any breach of any provision hereof shall not be construed to be a
               waiver of any succeeding breach of that provision or a waiver of
               any other provision of this Agreement.

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Mr. Gerard A. Wills
November 10, 1998
Page 8


          24.  INDEMNIFICATION.  With respect to any claim against you arising
               out of your work for MBI as an officer or employee, you shall
               have rights of indemnification against MBI under MBI's
               certificate of incorporation and bylaws equivalent to those of an
               MBI officer.


                                      * * * *

     If you are in agreement with these items, please execute the duplicate
originals of this Agreement and return them to Laura Gross.

     Let me take this opportunity to thank you for your services to MBI over
the past several years.  We all wish you every success in your future
endeavors.

                                       Sincerely,




                                       Bobba Venkatadri
                                       President and Chief Executive Officer

AGREED TO BY:



--------------------------------------
Gerard A. Wills

Date:
      --------------------------------




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Mr. Gerard A. Wills
November 10, 1998
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                                    ATTACHMENT