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                                                                     Exhibit 4.2

                                                                    CONFIDENTIAL
                                                               EXECUTION VERSION

                            CLASS B WARRANT AGREEMENT

     This CLASS B WARRANT AGREEMENT (this "Warrant Agreement") is dated and
entered into as of February 24, 2006, by and between ORTHOLOGIC CORP., a
Delaware corporation (the "Company"), and PHARMABIO DEVELOPMENT INC., a North
Carolina corporation ("PharmaBio").

     WHEREAS, the Company and PharmaBio have entered into the Common Stock and
Warrant Purchase Agreement (the "Purchase Agreement"), and the Registration
Rights Agreement (the "Registration Rights Agreement"), each dated as of the
date hereof;

     WHEREAS, the Company and Quintiles, Inc. ("Quintiles"), an affiliate of
PharmaBio, have entered into a Master Services Agreement also dated as of the
date hereof (the "Services Agreement");

     WHEREAS, pursuant to the Purchase Agreement, the Company desires to grant
to PharmaBio the rights set forth in this Warrant Agreement;

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by the parties, the parties agree
as follows:

     1. The Warrant.

          (a) The Company hereby agrees to issue and sell to PharmaBio, its
designee or assigns (the "Holder") 80,000 shares (the "Warrant Shares") of the
Company's Common Stock, $.0005 par value per share ("Common Stock"), at an
exercise price of Six Dollars and Thirty-Nine Cents ($6.39) per share (the
"Exercise Price") (such Exercise Price was calculated as follows: the average of
the closing prices of the shares of Common Stock for the 15 trading days prior
to the date hereof, multiplied by 115%), upon the terms and conditions herein
set forth, including the vesting schedule set forth in this Section 1. The
Exercise Price and the number of Warrant Shares purchasable upon exercise of
this Warrant Agreement are subject to adjustment from time to time as provided
in Section 4 of this Warrant Agreement.

          (b) Upon **** (the "Milestone"), the Holder's right to exercise this
Warrant Agreement will vest as follows:

               (i) if ****, One Hundred Percent (100%) of the Warrant Shares
               shall vest;

               (ii) if ****, Seventy-Five (75%) of the Warrant Shares shall
               vest;

               (iii) if ****, Fifty Percent (50%) of the Warrant Shares shall
               vest;

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.

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               (iv) if ****, none of the Warrant Shares shall vest; and

               (v) any Warrant Shares not vested by **** shall expire.

          (c) In the event that the Milestone fails to be achieved, or fails to
be achievable, by ****, or by another date specified in the vesting schedule set
forth in Section 1(b) above, and such failure is not caused solely by Quintiles,
then the Joint Development Committee (as defined in the Services Agreement)
shall promptly and in good faith review the Milestone, the existing vesting
schedule, and the events and circumstances that caused or resulted in such
failure; and the Joint Development Committee shall determine a new vesting
schedule that shall extend each date within the existing vesting schedule by the
duration of the events or circumstances that caused or resulted in such failure,
up to one year; provided that the vesting schedule shall be extended pursuant to
this Section 1(c) only once. The parties hereto promptly shall enter into an
appropriate amendment to this Warrant Agreement reflecting such extension.

          (d) Notwithstanding Section 1(b), the Holder's right to exercise this
Warrant Agreement will vest upon a Change of Control. "Change of Control" means
the occurrence of any of the following: (a) any "person" or "group" (as such
terms are defined in Section 13(d) and Section 14(d) of the Securities Exchange
Act of 1934, as amended, or any successor provisions (the "Exchange Act"))
becomes the "beneficial owner" (as determined in accordance with Rule 13d-3
under the Exchange Act), directly or indirectly, of shares of voting securities
of the Company representing 50% or more of the total voting power of all
outstanding voting securities of the Company; (b) the sale, lease, license,
exchange or other transfer (in one or a series of transactions) of all or
substantially all of the assets of the Company, or all or substantially all of
the assets relating to TP508; or (c) any merger, consolidation, share exchange,
business combination or similar transaction in which the Company is not the
surviving entity or in which the holders of the outstanding shares of stock of
the Company immediately prior to such transaction hold, immediately after such
transaction, less that 51% of the total voting power of the outstanding
securities of the surviving or resulting entity in such transaction.

     2. Expiration Date. This Warrant Agreement, and the Holder's right to
purchase any of the Warrant Shares, will expire at 5:00 p.m. Eastern Time on the
tenth anniversary of the date of this Warrant Agreement (the "Expiration Date").

     3. Exercise of this Warrant Agreement. (a) The Holder may exercise this
Warrant Agreement, on any Business Day, at any time from and after the date
hereof and prior to the Expiration Date, in whole or in part, as adjusted from
time to time as provided in Section 4 of this Warrant Agreement, by: (a) the
surrender of this Warrant Agreement, with the Exercise Form substantially in the
form attached hereto as Annex A properly completed and executed, at the
principal office of the Company, and (b) upon payment by the delivery of a
certified check or official bank check or wire transfer of immediately available
funds, payable to the order of the Company in an amount equal to the aggregate
purchase price for the Warrant Shares being purchased upon such exercise. Upon
receipt thereof by the Company, the Holder will be deemed to be the holder of
record of the Warrant Shares issuable upon such exercise as of the close of
business on the date of such receipt by the Company, and the Company will
promptly execute or cause to be executed and delivered to the Holder, a
certificate or certificates representing the

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


                                        2

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aggregate number of Warrant Shares specified in the Exercise Form. If this
Warrant Agreement is exercised only in part, the Company will, at the time of
delivery of said stock certificate or certificates, deliver to the Holder a new
Warrant Agreement of like tenor evidencing the right of the Holder to purchase
the remaining Warrant Shares then covered by this Warrant Agreement. "Business
Day" shall mean any day, other than a Saturday, Sunday or legal holiday during
which banks in North Carolina, United States are open for the conduct of their
banking business.

          (b) In lieu of exercising this Warrant Agreement, the Holder may elect
to receive shares equal to the value of this Warrant Agreement (or the portion
of the Warrant Shares hereunder being cancelled or surrendered) by sending
written notice of such election to the Company, in which event the Company shall
deliver to the Holder a stock certificate representing a number of shares of
Common Stock computed using the following formula:

                                   X = Y(A-B)
                                       -----
                                         A

Where:

     X = the number of shares of Common Stock to be issued to the Holder

     Y = the number of shares of Common Stock purchasable under this Warrant
         Agreement as to which the Holder is then exercising this Warrant
         Agreement

     A = the fair market value of one share of Common Stock

     B = the Exercise Price (as adjusted to the date of such calculations)

          (c) For purposes of this Section, "fair market value" of one share of
Common Stock shall mean the closing price reported on the Nasdaq National Market
or the principal exchange on which the Common Stock is listed, or the average of
the closing bid and asked prices of the Common Stock quoted in the
Over-The-Counter market, whichever is applicable, in each such case averaged
over a period of fifteen (15) consecutive trading days immediately preceding the
date that the Exercise Form is delivered to the Company. If the Common Stock is
not traded on such market or exchange, or Over-The-Counter, the fair market
value of the Common Stock will be the price per share which the Company could
obtain from a willing buyer for shares sold by the Company from authorized but
unissued shares, as agreed upon by the Company and the Holder in good faith or,
absent such agreement, as shall be determined by arbitration instituted by
either party under the rules of the American Arbitration Association.

          (d) If this Warrant Agreement has not been exercised prior to the
Expiration Date, the Holder shall be deemed to have elected, prior to the close
of business on the Expiration Date, to receive shares pursuant to this Section
3.

     4. Certain Adjustments. The Exercise Price at which Warrant Shares may be
purchased and the number of Warrant Shares to be purchased upon exercise of this
Warrant Agreement are subject to change or adjustment from time to time as
follows:

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


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          (a) Merger, Sale of Assets, etc. If at any time while this Warrant
Agreement, or any portion hereof, is outstanding and unexpired there shall be
(i) a reorganization (other than a combination, reclassification, exchange or
subdivision of shares otherwise provided for herein), (ii) a merger or
consolidation of the Company with or into another corporation or entity in which
the Company is not the surviving entity, or a reverse triangular merger or share
exchange in which the Company is the surviving entity but the shares of the
Company's capital stock outstanding immediately prior to the merger or share
exchange are exchanged or converted by virtue of the merger or share exchange
into other property, whether in the form of securities, cash, or otherwise, or
(iii) a sale, lease, license or other transfer of all or substantially all of
the Company's properties or assets to any other person or entity, then, as a
part of such reorganization, merger, consolidation, exchange or other transfer,
lawful provision shall be made so that the Holder shall thereafter be entitled
to receive upon exercise of this Warrant Agreement, during the period specified
herein and upon payment of the Exercise Price then in effect, the number of
shares of stock or other securities or property resulting from such
reorganization, merger, consolidation, exchange or other transfer that a holder
of the shares deliverable upon exercise of this Warrant Agreement would have
been entitled to receive in such reorganization, merger, consolidation, exchange
or other transfer if this Warrant Agreement had been exercised immediately
before the record date of (or the date of, if no record date is fixed) such
reorganization, merger, consolidation, exchange or other transfer, all subject
to further adjustment as provided in this Section 4. The foregoing provisions of
this Section 4(a) shall similarly apply to successive reorganizations, mergers,
consolidations, exchanges or other transfers and to the stock or securities of
any other corporation that are at the time receivable upon the exercise of this
Warrant Agreement. If the per-share consideration payable to the Holder hereof
for shares in connection with any such transaction is in a form other than cash
or marketable securities, then the value of such consideration shall be
reasonably determined in good faith by the Company's Board of Directors. In all
events, appropriate adjustment (as reasonably determined in good faith by the
Company's Board of Directors) shall be made in the application of the provisions
of this Warrant Agreement with respect to the rights and interests of the Holder
after any of the above-referenced transactions, to the end that the provisions
of this Warrant Agreement shall be applicable after such event, as near as
reasonably may be, in relation to any shares or other property deliverable after
such event upon exercise of this Warrant Agreement.

          (b) Reclassification, etc. If the Company, at any time while this
Warrant Agreement, or any portion hereof, remains outstanding and unexpired, by
reclassification of securities or otherwise, shall change any of the securities
as to which purchase rights under this Warrant Agreement exist into the same or
a different number of securities of any other class or classes, this Warrant
Agreement shall thereafter represent the right to acquire such number and kind
of securities as the Holder would have received if this Warrant Agreement had
been exercised in full immediately prior to such reclassification or other
change or immediately prior to the record date with respect thereto and the
Exercise Price therefor shall be appropriately adjusted, all subject to further
adjustment as provided in this Section 4. The foregoing provisions of this
Section 4(b) shall similarly apply to successive reclassifications or other
changes.

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


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          (c) Split, Subdivision or Combination of Shares. If the Company, at
any time while this Warrant Agreement, or any portion hereof, remains
outstanding and unexpired, shall split, subdivide or combine the securities as
to which purchase rights under this Warrant Agreement exist, into a different
number of securities of the same class, the Exercise Price for such securities
shall be proportionately decreased in the case of a split or subdivision or
proportionately increased in the case of a combination. Upon each adjustment in
the Exercise Price pursuant to this subsection, the number of shares of such
securities purchasable hereunder shall be adjusted, to the nearest whole share,
to the product obtained by multiplying the number of shares purchasable
immediately prior to such adjustment in the Exercise Price by a fraction, the
numerator of which shall be the Exercise Price immediately prior to such
adjustment and the denominator of which shall be the Exercise Price immediately
thereafter.

          (d) Certificate as to Adjustments. Upon the occurrence of each
adjustment pursuant to this Section 4, the Company at its expense shall promptly
compute such adjustment in accordance with the terms hereof and furnish to any
Holder of this Warrant Agreement a certificate signed by its Chief Financial
Officer setting forth such adjustment and showing in detail the event requiring
the adjustment, the amount of such adjustment, the method by which such
adjustment was calculated, the Exercise Price at the time in effect, and the
number of shares and the amount, if any, of the property that at the time would
be received upon the exercise of this Warrant Agreement, together with the facts
upon which such adjustment is based. The Company shall, upon the written
request, at any time, of any Holder, promptly furnish or cause to be furnished
to such Holder a like certificate setting forth: (i) all such previous
adjustments; (ii) the Exercise Price at the time in effect; and (iii) the number
of shares and the amount, if any, of other property that at the time would be
received upon the exercise of this Warrant Agreement.

          (e) No Dilution or Impairment. The Company will not, by amendment of
its certificate of incorporation or through any reorganization,
recapitalization, reclassification, transfer of assets, consolidation, merger,
business combination, or dissolution, avoid or seek to avoid the intent of this
Section 4 or the observance or performance of any of the terms to be observed or
performed by the Company under this Warrant Agreement, but will at all times in
good faith assist in the carrying out of all the provisions of this Section 4
and in the taking of all such action as may be necessary or appropriate in order
to protect the rights of the holder of this Warrant Agreement against
impairment.

          (f) Conformity with Warrant Agreement. In the event that at any time,
as a result of any adjustment made pursuant to this Section 4, the Holder
thereafter shall become entitled to receive any shares of capital stock of the
Company other than Common Stock, thereafter the number of such other shares so
receivable upon exercise of the Warrant Agreement shall be subject to adjustment
from time to time in a manner and on terms as nearly equivalent as practicable
to the provisions with respect to the Common Stock contained in this Section 4.

     5. Fractional Shares. Fractional shares will not be issued upon the
exercise of this Warrant Agreement, but in any case where the Holder would,
except for the provisions of this Section, be entitled under the terms of this
Warrant Agreement to receive a fractional share upon the exercise of this
Warrant Agreement, the Company will, upon the exercise of this Warrant

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


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Agreement for the largest number of whole shares then called for, pay a sum in
cash equal to the excess of the fair market value of such fractional share
(determined in such reasonable manner as may be prescribed by the Board of
Directors of the Company in its discretion) over the proportional part of the
per share purchase price represented by such fractional share.

     6. Notices of Certain Events. In case:

          (a) the Company shall take a record of the holders of its Common Stock
(or other stock or securities at the time receivable upon the exercise of this
Warrant Agreement) for the purpose of entitling them to receive any dividend or
other distribution, or stock subdivision or combination, or any right to
subscribe for or purchase any shares of stock of any class or any other
securities, or to receive any other right, or

          (b) of any reorganization or recapitalization of the Company, any
reclassification of the capital stock of the Company, any consolidation, merger,
share exchange or other business combination of the Company with or into another
corporation or entity, or any sale, lease, license or other transfer of all or
substantially all of the assets of the Company to another corporation or entity,
or

          (c) of any voluntary dissolution, liquidation or winding-up of the
Company, then, and in each such case, the Company will cause written notice
thereof to be delivered to the Holder specifying, as the case may be, (i) the
date on which a record is to be taken for the purpose of such dividend,
distribution or right, and stating the amount and character of such dividend,
distribution or right or (ii) the date on which such reorganization,
recapitalization, reclassification, consolidation, merger, share exchange,
business combination, transfer, dissolution, liquidation or winding-up is to
take place, and the time, if any is to be fixed, as of which the holders of
record of Common Stock (or such stock or securities at the time receivable upon
the exercise of this Warrant Agreement) shall be entitled to exchange their
shares of Common Stock (or such other stock or securities) for securities or
other property deliverable upon such reorganization, reclassification,
recapitalization, consolidation, merger, share exchange, business combination,
transfer, dissolution, liquidation or winding-up. Such notice shall be delivered
at least ten (10) Business Days prior to the date required to be specified
therein pursuant to this Section 6.

     7. No Rights as Stockholder; Limitation of Liability. This Warrant
Agreement, as distinct from the shares for which this Warrant Agreement is
exercisable, will not entitle the Holder to any of the rights of a stockholder
of the Company. No provision of this Warrant Agreement, prior to the exercise of
this Warrant Agreement, and no mere enumeration herein of the rights or
privileges of the Holder, will give rise to any liability of the Holder for the
purchase price or as a stockholder of the Company, whether such liability is
asserted by the Company or by creditors of the Company.

     8. Miscellaneous.

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


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          (a) Successors and Assigns. This Warrant Agreement shall be binding on
and inure to the benefit of the Holder and the Company and their respective
successors and assigns.

          (b) Amendments and Waivers. This Warrant Agreement and any provision
hereof may be amended, changed, waived, discharged or terminated only by an
instrument in writing signed by both parties hereto.

          (c) Loss, Theft, Destruction or Mutilation. Upon receipt by the
Company of evidence reasonably satisfactory to it that this Warrant Agreement
has been lost, stolen, destroyed or mutilated, and in the case of any lost,
stolen or destroyed Warrant Agreement, an indemnity reasonably satisfactory to
the Company, or in the case of a mutilated Warrant Agreement, upon surrender and
cancellation hereof, the Company will execute and deliver in the name of the
registered holder of this Warrant Agreement, in exchange and substitution for
the Warrant Agreement so lost, stolen, destroyed or mutilated, a new Warrant
Agreement of like tenor and amount.

          (d) Warrant Exchangeable for Different Denominations. This Warrant
Agreement is exchangeable, upon the surrender hereof by the Holder at the
principal office of the Company for new Warrant Agreements of like tenor
representing in the aggregate the right to purchase the number of shares which
may be purchased hereunder, each of such new Warrant Agreements to represent the
right to purchase such number of Warrant Shares as shall be designated by said
Holder hereof at the time of such surrender.

          (e) Law Governing. This Warrant Agreement will be governed by, and
construed and enforced in accordance with, the laws of the State of North
Carolina, without regard to conflicts-of-laws principles that would require the
application of any other law.

          (f) Entire Agreement. This Warrant Agreement, together with the
Purchase Agreement, the Registration Rights Agreement, and the other transaction
documents referred to therein or contemplated thereby, constitutes the full and
entire understanding and agreement among the parties with regard to the subject
matter of this Warrant Agreement, and supersedes all prior agreements,
understandings, inducements or conditions, express or implied, oral or written,
with respect to the subject matter of this Warrant Agreement.

          (g) Notices. Unless otherwise provided herein, all notices, requests,
demands and other communications required or permitted under this Warrant
Agreement shall be in writing and will be deemed to have been duly made and
received: (i) upon personal delivery; (ii) three (3) Business Days after deposit
with the United States Post Office, by registered or certified mail or by first
class mail, postage prepaid, addressed as set forth below; or (iii) one (1)
Business Day after deposit with a nationally recognized, overnight courier (for
next business day delivery), shipping prepaid, addressed as set forth below:

     If to Company:        OrthoLogic Corp.
                           1275 West Washington Street
                           Tempe, Arizona 85281
                           Attn: James M. Pusey, M.D.

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


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                           Facsimile: (602) 470-7080

     With a copy to
     (which shall not
     constitute notice):   Quarles & Brady Streich Lang LLP
                           One Renaissance Square
                           Two North Central Avenue
                           Phoenix, Arizona 85004
                           Attn: Steven P. Emerick
                           Facsimile: (602) 417-2980

     If to Purchaser:      PharmaBio Development Inc.
                           4709 Creekstone Drive
                           Suite 200 Riverbirch Building
                           Durham, NC 27703
                           Attn: President
                           Facsimile: (919) 998-2090

     With a copy to
     (which shall not
     constitute notice):   Smith, Anderson, Blount, Dorsett
                           Mitchell & Jernigan, L.L.P.
                           2500 Wachovia Capitol Center
                           Raleigh, NC 27601
                           Attn: Christopher B. Capel
                           Facsimile: (919) 821-6800

Either party may change the address to which communications are to be sent by
giving five (5) Business Days' advance notice of such change of address to the
other party in conformity with the provisions of this Section.

          (h) Execution; Counterparts. This Warrant Agreement and any amendment
hereto may be executed in counterparts, each of which when executed and
delivered shall be deemed to be an original and all of which counterparts taken
together shall constitute but one and the same instrument. The exchange of
copies of this Warrant Agreement or amendments thereto and of signature pages by
facsimile transmission or by email transmission in portable digital format, or
similar format, shall constitute effective execution and delivery of such
instrument(s) as to the parties and may be used in lieu of the original Warrant
Agreement or amendment for all purposes. Signatures of the parties transmitted
by facsimile or by email transmission in portable digital format, or similar
format, shall be deemed to be their original signatures for all purposes.

                            [signature page follows]

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.


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                  [Signature Page to Class B Warrant Agreement]

     IN WITNESS WHEREOF, the parties have caused this Warrant Agreement to be
duly executed and delivered as of the day and year first written above.

                                        ORTHOLOGIC CORP.


                                        By: /s/ Les M. Taeger
                                        Name: Les M. Taeger
                                        Title: CFO


                                        PHARMABIO DEVELOPMENT INC.

                                        By:  /s/ Patrick B. Jordan
                                        Name: Patrick B. Jordan
                                        Title: Vice President,
                                               Corporate Development


**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.

<PAGE>

                                                                         ANNEX A

                                  EXERCISE FORM

                     TO BE EXECUTED BY THE REGISTERED HOLDER
              TO EXERCISE THE ATTACHED CLASS B WARRANT AGREEMENT OF

                                ORTHOLOGIC CORP.

     The undersigned, [________________], pursuant to the provisions of the
Class B Warrant Agreement between OrthoLogic Corp. (the "Company") and PharmaBio
Development Inc. dated as of February 24, 2006 (the "Warrant Agreement"), hereby
elects to exercise the Warrant Agreement by agreeing to subscribe for and
purchase [_______________] shares (the "Warrant Shares") of Common Stock, $.0005
par value per share, of the Company, and hereby makes payment of $[___________]
by certified or official bank check or wire transfer of immediately available
funds payable to the order of the Company in payment of the exercise price
therefor.

     The undersigned acknowledges that the sale, transfer, assignment or
hypothecation of the Warrant Shares to be issued upon exercise of this Warrant
Agreement is subject to the terms and conditions of the Warrant Agreement.

                                        PharmaBio Development Inc.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        Address: 4709 Creekstone Drive
                                                 Suite 200 Riverbirch Building
                                                 Durham, NC 27703

Dated:           ,
       ----------  -----

**** Text has been omitted pursuant to a confidentiality request. Omitted text
     has been filed with the Securities and Exchange Commission.