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                                                                   Exhibit 10.42



                                 ACUSPHERE, INC.

                        INCENTIVE STOCK OPTION AGREEMENT


     Acusphere, Inc., a Delaware corporation (the "Corporation"), hereby grants
this 26th day of , 2001 to James R Fitzgerald, Jr. (the "Optionee"), an option
to purchase a maximum of 275,000 shares (the "Option Shares") of its Common
Stock, $.01 par value, at the price of $1.20 per share, on the following terms
and conditions:

     1.   GRANT UNDER 1994 STOCK PLAN. This option is granted pursuant to and is
governed by the Corporation's 1994 Stock Plan (the "Plan") and, unless the
context otherwise requires, terms used herein shall have the same meaning as in
the Plan. Determinations made in connection with this option pursuant to the
Plan shall be governed by the Plan as it exists on this date.

     2.   GRANT AS INCENTIVE STOCK OPTION; OTHER OPTIONS. This option is
intended to qualify as an incentive stock option under Section 422 of the
Internal Revenue Code of 1986, as amended (the "Code") and the Board of
Directors intends to take appropriate action, if necessary, to achieve this
result. This option is in addition to any other options heretofore or hereafter
granted to the Optionee by the Corporation, but a duplicate original of this
instrument shall not effect the grant of another option.

     3.   EXTENT OF OPTION IF BUSINESS RELATIONSHIP CONTINUES. If the Optionee
has continued to serve the Corporation or any Related Corporation in the
capacity of an employee, officer, director or consultant (such service is
described herein as maintaining or being involved in a "Business Relationship"
with the Corporation), the Optionee may exercise this option for such percentage
of the total Option Shares as is set forth opposite the applicable date as
follows:

          On September 10, 2001            -   0%

          On or after September 10, 2001   -   An additional 2.08% for each
          but prior to September 10, 2005      complete month during which the
                                               Optionee is employed by, a
                                               consultant to, or a director of
                                               the Corporation after
                                               September 10, 2001

          On or after September 10, 2005   -   100%


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The foregoing rights are cumulative and, while the Optionee continues to
maintain a Business Relationship with the Corporation or any Related
Corporation, may be exercised up to and including the date which is ten years
and one day from the date this option is granted. All of the foregoing rights
are subject to Sections 4 and 5, as appropriate, if the Optionee ceases to
maintain a Business Relationship with the Corporation or dies, becomes disabled
or undergoes dissolution while involved in a Business Relationship with the
Corporation.

     4.   TERMINATION OF BUSINESS RELATIONSHIP. If the Optionee ceases to
maintain a Business Relationship with the Corporation, other than by reason of
death or disability as defined in Section 5, no further installments of this
option shall become exercisable and this option shall terminate after the
passage of sixty (60) days from the date the Business Relationship ceases, but
in no event later than the scheduled expiration date. In such a case, the
Optionee's only rights hereunder shall be those which are properly exercised
before the termination of this option.

     5.   DEATH; DISABILITY; DISSOLUTION. If the Optionee is a natural person
who dies while involved in a Business Relationship with the Corporation, this
option may be exercised, to the extent otherwise exercisable on the date of his
death, by his estate, personal representative or beneficiary to whom this option
has been assigned pursuant to Section 10, at any time within 180 days after the
date of death, but not later than the scheduled expiration date. If the Optionee
is a natural person whose Business Relationship with the Corporation is
terminated by reason of his disability (as defined in the Plan), this option may
be exercised, to the extent otherwise exercisable on the date the Business
Relationship was terminated, at any time within 180 days after the date of such
termination, but not later than the scheduled expiration date. At the expiration
of such 180-day period or the scheduled expiration date, whichever is the
earlier, this option shall terminate and the only rights hereunder shall be
those as to which the option was properly exercised before such termination. If
the Optionee is a corporation, partnership, trust or other entity that is
dissolved, liquidated, becomes subject to a voluntary or involuntary bankruptcy
proceeding, has a receiver appointed for all or a substantial portion of its
property or enters into a merger or acquisition with respect to which such
optionee is not the surviving entity at the time when such entity is involved in
a Business Relationship with the Corporation, this Option shall immediately
terminate as of the date of such event, and the only rights hereunder shall be
those as to which this option was properly exercised before such dissolution or
other event.

     6.   PARTIAL EXERCISE. Exercise of this option up to the extent above
stated may be made in part at any time and from time to time within the above
limits, except that this option may not be exercised for a fraction of a share
unless such exercise is with respect to the final installment of stock subject
to this option and a fractional share (or cash in lieu thereof) must be issued
to permit the Optionee to exercise completely such final installment. Any
fractional share with respect to which an installment of this option cannot be
exercised because of the limitation contained in the preceding sentence shall


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remain subject to this option and shall be available for later purchase by the
Optionee in accordance with the terms hereof.

     7.   PAYMENT OF PRICE. The option price is payable in United States dollars
and may be paid:

          (a) in cash or by check, or any combination of the foregoing, equal in
amount to the option price; or

          (b) in the discretion of the Corporation's Board of Directors, in
cash, by check, by delivery of shares of the Corporation's Common Stock having a
fair market value (as determined by the Board of Directors) equal as of the date
of exercise to the option price, or by any combination of the foregoing, equal
in amount to the option price.

     Notwithstanding the foregoing, the Employee may not pay any part of the
exercise price hereof by transferring Common Stock to the Corporation if such
Common Stock is both subject to a substantial risk of forfeiture and not
transferable within the meaning of Section 83 of the Code.

     8.   METHOD OF EXERCISING OPTION. Subject to the terms and conditions of
this Agreement, this option may be exercised by written notice to the
Corporation, at the principal executive office of the Corporation, or to such
transfer agent as the Corporation shall designate. Such notice shall state the
election to exercise this option and the number of shares for which it is being
exercised and shall be signed by the person or persons so exercising this
option. Such notice shall be accompanied by payment of the full purchase price
of such shares, and the Corporation shall deliver a certificate or certificates
representing such shares as soon as practicable after the notice shall be
received. Such certificate or certificates shall be registered in the name of
the person or persons so exercising this option (or, if this option shall be
exercised by the Optionee and if the Optionee shall so request in the notice
exercising this option, shall be registered in the name of the Optionee and
another person jointly, with right of survivorship) and shall be delivered as
provided above to or upon the written order of the person or persons exercising
this option. In the event this option shall be exercised, pursuant to Section 5
hereof, by any person or persons other than the Optionee, such notice shall be
accompanied by appropriate proof of the right of such person or persons to
exercise this option. All shares that shall be purchased upon the exercise of
this option as provided herein shall be fully paid and non-assessable.

     9.   RESTRICTIONS ON TRANSFER. Option Shares may not be transferred without
the Corporation's written consent, except by will, by the laws of descent and
distribution, or in accordance with the provisions of Section 16, if applicable.
Option Shares will be of an illiquid nature and will be deemed to be "restricted
securities" for purposes of the Securities Act of 1933, as amended. Accordingly,
such shares must be sold in compliance with the registration requirements of
such Act or an exemption therefrom.


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     10.  OPTION NOT TRANSFERABLE. This option is not transferable or assignable
except by the laws of descent and distribution. Only the Optionee or his estate
can exercise this option.

     11.  NO OBLIGATION TO EXERCISE OPTION. The grant and acceptance of this
option imposes no obligation on the Optionee to exercise it.

     12.  NO OBLIGATION TO CONTINUE BUSINESS RELATIONSHIP. The Corporation and
any Related Corporations are not by the Plan or this option obligated to
continue to maintain a business relationship with the Optionee.

     13.  NO RIGHTS AS STOCKHOLDER UNTIL EXERCISE. The Optionee shall have no
rights as a stockholder with respect to the Option Shares until a stock
certificate therefor has been issued to the Optionee and is fully paid for in
accordance with Section 7. Except as is expressly provided in the Plan with
respect to certain changes in the capitalization of the Corporation, no
adjustment shall be made for dividends or similar rights for which the record
date is prior to the date such stock certificate is issued.

     14.  CAPITAL CHANGES AND BUSINESS SUCCESSIONS.

     (a) It is the purpose of this option to encourage the Optionee to work for
the best interests of the Corporation and its stockholders. Since, for example,
that might require the issuance of a stock dividend or a merger with another
corporation, the purpose of this option would not be served if such a stock
dividend, merger or similar occurrence would cause the Optionee's rights
hereunder to be diluted or terminated and thus be contrary to the Optionee's
interest. The Plan contains extensive provisions designed to preserve options at
full value in a number of contingencies. Therefore, except as specifically set
forth in paragraph (b) below, provisions in the Plan for adjustment with respect
to stock subject to options and the related provisions with respect to
successors to the business of the Corporation are hereby made applicable
hereunder and are incorporated herein by reference.

     (b) Upon the consummation of an Acquisition (as defined below): (x) this
Agreement shall remain the obligation of the Corporation or be assumed by the
surviving or acquiring entity, and there shall be automatically substituted for
the shares of Common Stock then subject to this Agreement the consideration
payable with respect to the outstanding shares of Common Stock in connection
with the Acquisition and (y) this Option shall become immediately exercisable in
full for all outstanding Option Shares. For purposes of this Agreement,
"Acquisition" shall mean: (x) the sale of the Corporation by merger in which the
shareholders of the Corporation in their capacity as such no longer own a
majority of the outstanding equity securities of the Corporation (or its
successor); or (y) the sale of the Corporation (in any single transaction or
series of related transactions) by any sale of all or substantially all of the
assets or 50% or more of the voting capital stock of the Corporation (other than
in a spin-off or similar transaction effected through a distribution of assets
to the Corporation's stockholders) or (z) any other acquisition of the business
of the Corporation, as determined by the Board.

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     15.  WITHHOLDING TAXES. If the Corporation or any related corporation in
its discretion determines that it is obligated to withhold any tax in connection
with the exercise of this option, or in connection with the transfer of, or the
lapse of restrictions on, any Common Stock or other property acquired pursuant
to this option, the Optionee hereby agrees that the Corporation or related
corporation may withhold from the Optionee's wages or other remuneration the
appropriate amount of tax. At the discretion of the Corporation or related
corporation, the amount required to be withheld may be withheld in cash from
such wages or other remuneration, or in kind from the Common Stock otherwise
deliverable to the Optionee on exercise of this option. The Optionee further
agrees that, if the Corporation or related corporation does not withhold an
amount from the Optionee's wages or other remuneration sufficient to satisfy the
withholding obligation of the Corporation or related corporation, the Optionee
will reimburse the Corporation or related corporation on demand, in cash, for
the amount underwithheld.

     16.  CORPORATION'S RIGHT OF FIRST REFUSAL.

          (a) EXERCISE OF RIGHT: If the Optionee or the Optionee's legal
representative (the "Transferor") desires to transfer all or any part of the
Option Shares to any person other than the Corporation (an "Offeror"), the
Transferor shall: (i) obtain in writing an irrevocable and unconditional bona
fide offer (the "Offer") for the purchase thereof from the Offeror; and (ii)
give written notice (the "Option Notice") to the Corporation setting forth the
Optionee's desire to transfer such shares, which Option Notice shall be
accompanied by a photocopy of the Offer and shall set forth at least the name
and address of the Offeror and the price and terms of the bona fide offer. Upon
receipt of the Option Notice, the Corporation shall have an assignable option to
purchase any or all of such shares (the "Corporation Option Shares") specified
in the Option Notice, such option to be exercisable by giving, within 30 days
after receipt of the Option Notice, a written counter-notice to the Transferor.
If the Corporation elects to purchase any or all of such Corporation Option
Shares, it shall be obligated to purchase, and the Optionee shall be obligated
to sell to the Corporation, such Corporation Option Shares at the price and
terms indicated in the Offer within 30 days from the date of delivery by the
Corporation of such counter-notice.

          (b) SALE OF OPTION SHARES TO OFFEROR: The Transferor may, for 60 days
after the expiration of the 30-day period during which the Corporation may give
the counter-notice, sell, pursuant to the terms of the Offer, any or all of such
Corporation Option Shares not purchased or agreed to be purchased by the
Corporation or its assignee; provided, however, that the Transferor shall not
sell such Corporation Option Shares to the Offeror if the Offeror is a
competitor of the Corporation and the Corporation gives written notice to the
Transferor, within 30 days of its receipt of the Option Notice, stating that the
Transferor shall not sell such Corporation Option Shares to such Offeror; and
provided, further, that prior to the sale of such Corporation Option Shares to
the Offeror, the Offeror shall execute an agreement with the Corporation
pursuant to which the Offeror agrees to be subject to the restrictions set forth
in this Section 16. If any or all of


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such Corporation Option Shares are not sold pursuant to an Offer within the time
permitted above, the unsold Corporation Option Shares shall remain subject to
the terms of this Section 16.

          (c) ADJUSTMENTS FOR CHANGES IN CAPITAL STRUCTURE: If there shall be
any change in the Common Stock of the Corporation through merger, consolidation,
reorganization, recapitalization, stock dividend, stock split, combination or
exchange of shares, or the like, the restrictions contained in this Section 16
shall apply with equal force to additional and/or substitute securities, if any,
received by the Optionee in exchange for, or by virtue of his or her ownership
of, Corporation Option Shares.

          (d) FAILURE TO DELIVER CORPORATION OPTION SHARES: If the Transferor
fails or refuses to deliver on a timely basis duly endorsed certificates
representing Corporation Option Shares to be sold to the Corporation or its
assignee pursuant to this Section 16, the Corporation shall have the right to
deposit the purchase price for such Corporation Option Shares in a special
account with any bank or trust company in the Commonwealth of Massachusetts or
State of Delaware, giving notice of such deposit to the Transferor, whereupon
such Corporation Option Shares shall be deemed to have been purchased by the
Corporation. All such monies shall be held by the bank or trust company for the
benefit of the Transferor. All monies deposited with the bank or trust company
remaining unclaimed for two years after the date of deposit shall be repaid by
the bank or trust company to the Corporation on demand, and the Transferor shall
thereafter look only to the Corporation for payment. The Corporation may place a
legend on any stock certificate delivered to the Transferor reflecting the
restrictions on transfer provided in Section 9 hereof and this Section 16.

          (e) EXPIRATION OF CORPORATION'S RIGHT OF FIRST REFUSAL: The first
refusal rights of the Corporation set forth above shall remain in effect until
such time, if ever, as a distribution to the public is made of shares of the
Corporation's Common Stock pursuant to a registration statement filed under the
Securities Act of 1933, as amended (the "Act") or a successor statute, at which
time the first refusal rights of the Corporation set forth herein will
automatically expire.

     17.  PROVISION OF DOCUMENTATION TO OPTIONEE. By signing this Agreement the
Optionee acknowledges receipt of a copy of this Agreement and a copy of the
Plan.

     18.  MARKET "STAND-OFF" AGREEMENT. The Optionee hereby agrees that, during
the period of duration (not to exceed one hundred eighty (180) days) specified
by the Corporation and an underwriter of Common Stock or other securities of the
Corporation, following the effective date of a registration statement of the
Corporation filed under the Act, such Optionee shall not, to the extent
requested by the Corporation and such underwriter, directly or indirectly sell,
offer to sell, contract to sell (including, without limitation, any short sale),
grant any option to purchase or otherwise transfer or dispose of (other than to
donees who agree to be similarly bound) any securities of the Corporation held
by the Optionee at any time during such period except Common Stock

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included in such registration; provided however, that (i) such agreement shall
be applicable only with respect to an initial public offering of the
Corporation's securities and (ii) all officers and directors of the Corporation
and all other persons with registration rights enter into similar agreements.

     19.  MISCELLANEOUS.

          (a) NOTICES: All notices hereunder shall be in writing and shall be
deemed given when sent by certified or registered mail, postage prepaid, return
receipt requested, to the address set forth below. The addresses for such
notices may be changed from time to time by written notice given in the manner
provided for herein.

         (b) ENTIRE AGREEMENT; MODIFICATION: This Agreement constitutes the
entire agreement between the parties relative to the subject matter hereof, and,
except for Optionee's right to cancel outstanding options in exchange for
payment of $315,000 upon the occurrence of certain events as more particularly
described in the offer letter to Optionee dated as of September 10, 2001,
supersedes all proposals, written or oral, and all other communications between
the parties relating to the subject matter of this Agreement. This Agreement may
be modified, amended or rescinded only by a written agreement executed by both
parties.

          (c) SEVERABILITY: The invalidity, illegality or unenforceability of
any provision of this Agreement shall in no way affect the validity, legality or
enforceability of any other provision.

          (d) SUCCESSORS AND ASSIGNS: This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
assigns, subject to the limitations set forth in Section 10 hereof.

          (e) GOVERNING LAW: This Agreement shall be governed by and interpreted
in accordance with the laws of the state of Delaware without giving effect to
the principles of the conflicts of laws thereof. The preceding choice of law
provision shall apply to all claims, under any theory whatsoever, arising out of
the relationship of the parties contemplated herein.

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     IN WITNESS WHEREOF the Corporation and the Optionee have caused this
instrument to be executed, and the Optionee whose signature appears below
acknowledges receipt of a copy of the Plan and acceptance of an original copy of
this Agreement.

                                       ACUSPHERE, INC.



                                       By: /s/ Sherri C. Oberg
                                           --------------------------------

                                       Title: President

                                       Address: 38 Sidney Street
                                                Cambridge, MA 02139



                                       /s/ James R. Fitzgerald, Jr.
                                       ------------------------------------
                                       James R. Fitzgerald, Jr.

                                       Address:  44 Blueberry Hill Lane
                                                 Sudbury, MA 01776