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                                                                   EXHIBIT 10.20

                              CONSULTING AGREEMENT

            This Consulting Agreement ("Agreement") is entered into on April 11,
2005 by Greg Cobb ("Cobb") and ImaRx Therapeutics, Inc. ("ImaRx" or the
"Company").

                                    RECITALS

            A. ImaRx has offered and Cobb has accepted the position of Chief
Financial Officer of ImaRx.

            B. Cobb is scheduled to begin his assignment as CFO on April 27,
2005 (the "Start Date").

            C. ImaRx wishes to retain Cobb as a consultant until the Start Date
to assist with analysis of various financing options among other finance related
tasks in preparation for Cobb's transition to the CFO position.

                                   AGREEMENTS

            In consideration of the mutual releases and promises set forth below
and other valuable consideration, the sufficiency of which is hereby
acknowledged, the parties agree as follows:

      1.    Scope of Services

            Cobb agrees to help analyze various financing options for ImaRx as
well as other finance related tasks in preparation for Cobb's transition to the
CFO position (the "Services"). The scope of these Services shall include:

      2.    Location of Services

            Services shall be provided at locations deemed appropriate by the
parties. If Services are to be provided at ImaRx's place of business, ImaRx
shall supply Cobb with suitable office or meeting space, telephone service, and
support services as reasonable and necessary to the performance of Services.

      3.    Compensation

            A. Consulting Fees. ImaRx shall pay Cobb a consulting fee of $70.00
per hour for each hour expended performing the Services ("Consulting Fees").
During the Term of this Agreement, Cobb shall be responsible for all payroll and
other employment taxes related to consulting fees.

      4.    Expenses

            ImaRx shall reimburse Cobb for its reasonable out-of-pocket expenses
incurred in the performance of this Agreement, including but not limited to
airfare, ground transportation,

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parking, lodging, meals, long distance telephone, postage, overnight mail, and
the like ("Expenses").

      5.    Payment

            Invoices for Consulting Fees and Expenses, inclusive of reasonable
supporting documentation, shall be remitted by Cobb monthly and shall be payable
within 10 days.

      6.    Limitation of Liability

            In no event shall Cobb be liable to ImaRx or any third party for any
indirect, special, incidental, or consequential damages, including but not
limited to loss of profits, loss of data, or loss of good will, even if such
party has been informed of the possibility of such damages. This limitation of
liability shall survive the expiration or any termination of this agreement. In
no event will Cobb be liable to ImaRx for damages, whether based in contract,
tort, negligence, strict liability or otherwise, exceeding the amount payable
hereunder for the Services giving rise to such liability, or $5,000, whichever
is less.

      7.    Indemnification

            If Cobb becomes involved in any action, proceeding or investigation
(other than an action between Cobb and ImaRx) regarding any matter in this
Agreement, ImaRx will indemnify Cobb against any claims, liabilities or expenses
to which Cobb may become subject (including reasonable legal and other expenses)
unless such claims, liabilities or damages resulted from Cobb's gross
negligence, recklessness, bad faith or willful misconduct as finally determined
by a court of competent jurisdiction. ImaRx agrees that this indemnification
shall apply whether or not Cobb is a formal party to such actions, claims or
proceedings and that Cobb is entitled to separate counsel at ImaRx's expense in
connection with any of these matters. The parties further agree that Cobb shall
have indemnification rights under the ImaRx's Directors and Officers Insurance
Coverage and/or Articles of Incorporation.

      8.    Confidentiality and Nondisclosure

            Both parties acknowledge that each may gain access to confidential
and proprietary information of the other which is not publicly known and which
is designated as confidential or proprietary at the time of disclosure
("Proprietary Information"). ImaRx and Cobb agree that a party receiving
Proprietary Information ("Receiving Party") from the other party ("Disclosing
Party") will maintain same in confidence and not use such Proprietary
Information for any purpose outside the scope of this Agreement during the term
of this Agreement and for a period of two (2) years following expiration or
termination of this Agreement for any reason. The Receiving Party agrees to use
at least the same degree of care with Proprietary Information of the Disclosing
Party as it uses with its own. For purposes of this Agreement, Proprietary
Information does not include Information which: (a) is known to the Receiving
Party on a non-confidential basis prior to disclosure by the Disclosing Party;
(b) is or hereafter becomes publicly known without breach of this Agreement or
fault of the Receiving Party; (c) is disclosed to the Receiving Party by a third
party without restriction on disclosure and without breach of any nondisclosure
obligation; (d) is independently developed by Receiving

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Party without use of Proprietary Information of the Disclosing Party; or (e) is
received by the Receiving Party after the effective date of termination of this
Agreement.

      9.    Term

            The term of this Agreement shall commence on the above date and
expire upon the earlier of (a) written notice of either party or (b) the Start
Date (the "Term"). The Term may be extended by mutual agreement of the parties
in writing.

      10.   Severability

            In the event that any portion of this Agreement is found to be
unenforceable for any reason whatsoever, the unenforceable provision shall be
considered to be severable, and the remainder of this Agreement shall continue
in full force and effect.

      11.   Subsequent Modifications

            The terms of this Agreement may be altered or amended, in whole or
in part, only upon the written consent of all parties to this Agreement. No oral
agreement may modify any term of this Agreement.

      12.   Binding Effect

            This Agreement shall be binding upon and operate to the benefit of
the parties to this Agreement, the Released Parties and their successors and
assigns.

      13.   Entire Agreement

            This Agreement constitutes the sole and entire agreement of the
parties with respect to the subject matter hereof, and supersedes any and all
prior and contemporaneous agreements, promises, representations, negotiations,
and understandings of the parties, whether written or oral.

      14.   Governing Law

            This Agreement shall be governed by and construed in accordance with
the laws of the State of Arizona.

      15.   Waiver

            No waiver of any of the terms of this Agreement shall constitute a
waiver of any other terms, whether or not similar, nor shall any waiver be a
continuing waiver. No waiver shall be binding unless executed in writing by the
party making the waiver. Any party may waive any provision of this Agreement
intended for its benefit, but such waiver shall in no way excuse the other party
from the performance of any of its obligations under this Agreement.

      16.   Attorneys' Fees

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            In the event of litigation involving this Agreement, the
unsuccessful party agrees to pay the prevailing party's reasonable attorneys'
fees and costs.

IN WITNESS WHEREOF, the parties have entered into this Consulting Services
Agreement as of the Effective Date above written.

IMARX                                       COBB
ImaRx Therapeutics, Inc.

By:  /s/ Evan Unger                         By:    /s/ Greg Cobb
    ------------------------------              -----------------------------

Name: Evan Unger                            Name: Greg Cobb

Title: CEO

Date: 04-11-05                              Date: 4/11/05

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