PROMISSORY NOTE

Exhibit 4.1

PROMISSORY NOTE

Bio-Imaging Technologies, Inc.

826 Newtown- Yardley Road

Newtown, Pennsylvania 18940

(Individually and collectively “Borrower”)

Wachovia Bank, National Association

123 South Broad Street

Philadelphia, Pennsylvania 19109

(Hereinafter referred to as “Bank”)

Borrower promises to pay to the order of Bank, in lawful money of the United States of America, at its office indicated above or wherever else Bank may specify, the sum of Five Million and No/100 Dollars ($5,000,000.00) or such sum as may be advanced and outstanding from time to time, with interest on the unpaid principal balance at the rate and on the terms provided in this Promissory Note (including all renewals, extensions or modifications hereof, this “Note”),

RENEWAL/MODIFICATION. This Promissory Note renews, extends and/or modifies that certain Promissory Note dated May 15, 2004 (the “Original Promissory Note”), evidencing an original principal amount of $5,000,000.00. This Promissory Note is not a novation.

LOAN AGREEMENT. This Note is subject to the provisions of that certain Loan Agreement between Bank and Borrower dated May 17, 2005, as modified from time to time.

LINE OF CREDIT. Borrower may borrow, repay and reborrow, and, upon the request of Borrower, Bank shall advance and readvance under this Note from time to time until the maturity hereof (each an “Advance” and together the “Advances”), so long as the total principal balance outstanding under this Note at anyone time does not exceed the principal amount stated on the face of this Note, subject to the limitations described in any loan agreement to which this Note is subject Bank’s obligation to make Advances under this Note shall terminate if Borrower is in Default As of the date of each proposed Advance, Borrower shall be deemed to represent that each representation made in the Loan Documents is true as of such date.

If Borrower subscribes to Bank’s cash management services and such services are applicable to this line of credit, the terms of such service shall control the manner in which funds are transferred between the applicable demand deposit account and the line of credit for credit or debit to the line of credit.

USE OF PROCEEDS. Borrower shall use the proceeds of the loan(s) evidenced by this Note for the commercial purposes of Borrower, as follows: for working capital.

INTEREST RATE. Interest shall accrue on the unpaid principal balance of this Note from the date hereof at the LlBOR Market Index Rate plus 2,0%, as that rate may change from day to day in accordance with changes in the LlBOR Market Index Rate (“Interest Rate”), “LIBOR Market Index Rate”, for any day, means the rate for 1 month U.S. dollar deposits as reported on Telerate page 3750 as of 11:00 a.m., London time, on such day, or if such day is not a London business day, then the immediately preceding London business day (or if not so reported, then as determined by Bank from another recognized source or interbank quotation).

DEFAULT RATE. In addition to all other rights contained in this Note, if a Default (as defined herein) occurs and as long as a Default continues, all outstanding Obligations, other than Obligations under any swap agreements (as defined in 11 U.S.C. § 101, as in effect from time to time) between Borrower and Bank or its affiliates, shall bear interest at the Interest Rate plus 3% (“Default Rate”). The Default Rate shall also apply from acceleration until the Obligations or any judgment thereon is paid in full.

INTEREST AND FEE(S) COMPUTATION (ACTUAL/360). Interest and fees, if any, shall be computed on the basis of a 360-day year for the actual number of days in the applicable period (“Actual/360 Computation”). The Actual/360 Computation determines the annual effective interest yield by taking the stated (nominal) rate for a

year’s period and then dividing said rate by 360 to determine the daily periodic rate to be applied for each day in the applicable period. Application of the Actual/360 Computation produces an annualized effective rate exceeding the nominal rate.

REPAYMENT TERMS. This Note shall be due and payable in consecutive monthly payments of accrued interest only, commencing on June 1, 2005, and continuing on the same day of each month thereafter until fully paid. In any event, all principal and accrued interest shall be due and payable on June 30, 2006.

AUTOMATIC DEBIT OF CHECKING ACCOUNT FOR LOAN PAYMENT. Borrower authorizes Bank to debit demand deposit account number 2000011294955 or any other account with Bank (routing number 031000503) designated in writing by Borrower, beginning June 1, 2005 for any payments due under this Note. Borrower further certifies that Borrower holds legitimate ownership of this account and preauthorizes this periodic debit as part of its right under said ownership.

AVAILABILITY FEE. Borrower shall pay to Bank quarterly an availability fee equal to 0.20% per annum on the difference between (i) the face amount of this Note and (ii) the outstanding principal balance of this Note, for each day during the preceding calendar quarter or portion thereof, commencing on June 1, 2005 and continuing on the same day of each quarter thereafter, with a final payment due and payable on the date that all principal and accrued interest is paid in full.

APPLICATION OF PAYMENTS. Monies received by Bank from any source for application toward payment of the Obligations shall be applied to accrued interest and then to principal. If a Default occurs, monies may be applied to the Obligations in any manner or order deemed appropriate by Bank.

If any payment received by Bank under this Note or other Loan Documents is rescinded, avoided or for any reason returned by Bank because of any adverse claim or threatened action, the returned payment shall remain payable as an obligation of all persons liable under this Note or other Loan Documents as though such payment had not been made.

DEFINITIONS. Loan Documents. The term “Loan Documents”, as used in this Note and the other Loan Documents refers to all documents executed in connection with or related to the loan evidenced by this Note and any prior notes which evidence all or any portion of the loan evidenced by this Note, and any letters of credit issued pursuant to any loan agreement to which this Note is subject, any applications for such letters of credit and any other documents executed in connection therewith or related thereto, and may include, without limitation, a commitment letter that survives closing, a loan agreement, this Note, guaranty agreements, security agreements, security instruments, financing statements, mortgage instruments, any renewals or modifications, whenever any of the foregoing are executed, but does not include swap agreements (as defined in 11 U.S.C. § 101, as in effect from time to time). Obligations. The term “Obligations”, as used in this Note and the other Loan Documents, refers to any and all indebtedness and other obligations under this Note, all other obligations under any other Loan Document(s), and all obligations under any swap agreements (as defined in 11 U.S.C. § 101, as. in effect from time to time) between Borrower and Bank, or its affiliates, whenever executed. Certain Other Terms. All terms that are used but not otherwise defined in any of the Loan Documents shall have the definitions provided in the Uniform Commercial Code.

LATE CHARGE. If any payments are not timely made, Borrower shall also pay to Bank a late charge equal to 5% of each payment past due for 10 or more days. This late charge shall not apply to payments due at maturity or by acceleration hereof, unless such late payment is in an amount not greater than the highest periodic payment due hereunder.

Acceptance by Bank of any late payment without an accompanying late charge shall not be deemed a waiver of Bank’s right to collect such late charge or to collect a late charge for any subsequent late payment received.

ATTORNEYS’ FEES AND OTHER COLLECTION COSTS. Borrower shall pay all of Bank’s reasonable expenses incurred to enforce or collect any of the Obligations including, without limitation, reasonable arbitration, paralegals’, attorneys’ and experts’ fees and expenses, whether incurred without the commencement of a suit, in any trial, arbitration, or administrative proceeding, or in any appellate or bankruptcy proceeding.

USURY. If at any time the effective interest rate under this Note would, but for this paragraph, exceed the maximum lawful rate, the effective interest rate under this Note shall be the maximum lawful rate, and any amount received by Bank in excess of such rate shall be applied to principal and then to fees and expenses, or, if no such amounts are owing, returned to Borrower.

DEFAULT. If any of the following occurs, a default (“Default”) under this Note shall exist: Nonpayment; Nonperformance. The failure of timely payment or performance of the Obligations or default, however denominated, under this Note or any other Loan Documents. False Warranty. A warranty or representation made or deemed made in the Loan Documents or furnished Bank in connection with the loan evidenced by this Note proves materially false, or if of a continuing nature, becomes materially false. Cross Default. At Bank’s option, any default in payment or performance of any obligation under any other loans, contracts or agreements of Borrower, any Subsidiary or Affiliate of Borrower, any general partner of or the holder(s) of the majority ownership interests of Borrower with Bank or its affiliates (“Affiliate” shall have the meaning as defined in 11 U.S.C. § 101, as in effect from time to time, except that the term “Borrower” shall be substituted for the term “Debtor” therein; “Subsidiary” shall mean any business in which Borrower holds, directly or indirectly, a controlling interest). Cessation; Bankruptcy. The death of, appointment of a guardian for, dissolution of, termination of existence of, loss of good standing status by, appointment of a receiver for, assignment for the benefit of creditors of, or commencement of any bankruptcy or insolvency proceeding by or against Borrower, its Subsidiaries or Affiliates, if any, or any general partner of or the holder(s) of the majority ownership interests of Borrower, or any party to the Loan Documents. Material Capital Structure or Business Alteration. Without prior written consent of Bank, (i) a material alteration in the kind or type of Borrower’s business or that of Borrower’s Subsidiaries or Affiliates, if any; (ii) the sale of substantially all of the business or assets of Borrower, any of Borrower’s Subsidiaries or Affiliates or any guarantor, or a material portion (10% or more) of such business or assets if such a sale is outside the ordinary course of business of Borrower, or any of Borrower’s Subsidiaries or Affiliates or any guarantor, or more than 50% of the outstanding stock or voting power of or in any such entity in a single transaction or a series of transactions; (iii) the acquisition of substantially all of the business or assets or more than 50% of the outstanding stock or voting power of any other entity; or (iv) should any Borrower or any of Borrower’s Subsidiaries or Affiliates or any guarantor enter into any merger or consolidation. Material Adverse Change. Bank determines in good faith, in its sole discretion, that the prospects for payment or performance of the Obligations are impaired or there has occurred a material adverse change in the business or prospects of Borrower, financial or otherwise.

REMEDIES UPON DEFAULT. If a Default occurs under this Note or any Loan Documents, Bank may at any time thereafter, take the following actions: Bank Lien. Foreclose its security interest or lien against Borrower’s accounts without notice. Acceleration Upon Default. Accelerate the maturity of this Note and, at Bank’s option, any or all other Obligations, other than Obligations under any swap agreements (as defined in 11 U.S.C. § 101, as in effect from time to time) between Borrower and Bank, or its affiliates, which shall be due in accordance with and governed by the provisions of said swap agreements; whereupon this Note and the accelerated Obligations shall be immediately due and payable; provided, however, if the Default is based upon a bankruptcy or insolvency proceeding commenced by or against Borrower or any guarantor or endorser of this Note, all Obligations (other than Obligations under any swap agreement as referenced above) shall automatically and immediately be due and payable. Cumulative. Exercise any rights and remedies as provided under the Note and other Loan Documents, or as provided by law or equity.

FINANCIAL AND OTHER INFORMATION. Borrower shall deliver to Bank such information as Bank may reasonably request from time to time, including without limitation, financial statements and information pertaining to Borrower’s financial condition. Such information shall be true, complete, and accurate.

CONFESSION OF JUDGMENT. THE FOLLOWING PARAGRAPH SETS FORTH A POWER OF AUTHORITY FOR ANY ATTORNEY TO CONFESS JUDGMENT AGAINST BORROWER. IN GRANTING THIS WARRANT OF ATTORNEY TO CONFESS JUDGMENT AGAINST BORROWER THE BORROWER, FOLLOWING CONSULTATION WITH (OR DECISION NOT TO CONSULT) SEPARATE COUNSEL FOR BORROWER AND WITH KNOWLEDGE OF THE LEGAL EFFECT HEREOF HEREBY KNOWINGLY, INTENTIONALLY, VOLUNTARILY, INTELLIGENTLY AND UNCONDITIONALLY WAIVES ANY AND ALL RIGHTS THE BORROWER HAS OR MAY HAVE TO PRIOR NOTICE AND AN OPPORTUNITY FOR HEARING UNDER THE RESPECTIVE CONSTITUTIONS AND LAWS OF THE UNITED STATES OF AMERICA, COMMONWEALTH OF PENNSYLVANIA, OR ELSEWHERE INCLUDING, WITHOUT LIMITATION, A HEARING PRIOR TO GARNISHMENT AND ATTACHMENT OF THE BORROWER’S BANK ACCOUNT AND OTHER ASSETS. BORROWER ACKNOWLEDGES AND UNDERSTANDS THAT BY ENTERING INTO THIS NOTE CONTAINING A CONFESSION OF JUDGMENT CLAUSE THAT BORROWER IS VOLUNTARILY, INTELLIGENTLY AND KNOWINGLY GIVING UP ANY AND ALL RIGHTS, INCLUDING CONSTITUTIONAL RIGHTS, THAT BORROWER HAS OR MAY HAVE TO NOTICE AND A HEARING BEFORE JUDGMENT CAN BE ENTERED AGAINST BORROWER AND BEFORE THE BORROWER’S ASSETS, INCLUDING, WITHOUT LIMITATION, ITS BANK ACCOUNTS, MAY BE GARNISHED, LEVIED, EXECUTED UPON AND/OR ATTACHED. BORROWER UNDERSTANDS THAT ANY SUCH GARNISHMENT, LEVY, EXECUTION AND/OR

ATTACHMENT SHALL RENDER THE PROPERTY GARNISHED, LEVIED, EXECUTED UPON OR ATTACHED IMMEDIATELY UNAVAILABLE TO BORROWER. IT IS SPECIFICALLY ACKNOWLEDGED BY BORROWER THAT THE BANK HAS RELIED ON THIS WARRANT OF ATTORNEY AND THE RIGHTS WAIVED BY BORROWER HEREIN IN RECEIVING THIS NOTE AND AS AN INDUCEMENT TO GRANT FINANCIAL ACCOMMODATIONS TO THE BORROWER.

If a Default occurs under this Note or any other Loan Documents, each Borrower hereby jointly and severally authorizes and empowers any attorney of any court of record or the prothonotary or clerk of any county in the Commonwealth of Pennsylvania, or in any jurisdiction where permitted by law or the clerk of any United States District Court, to appear for Borrower in any and all actions which may be brought hereunder and enter and confess judgment against the Borrower or any of them in favor of the Bank for such sums as are due or may become due hereunder or under any other Loan Documents, together with costs of suit and actual collection costs including, without limitation, reasonable attorneys’ fees equal to 5% of the Obligations then due and owing but in no event less than $5,000.00, with or without declaration, without prior notice, without stay of execution and with release of all procedural errors and the right to issue executions forthwith. To the extent permitted by law, Borrower waives the right of inquisition on any real estate levied on, voluntarily condemns the same, authorizes the prothonotary or clerk to enter upon the writ of execution this voluntary condemnation and agrees that such real estate may be sold on a writ of execution; and also waives any relief from any appraisement, stay or exemption law of any state now in force or hereafter enacted. Borrower further waives the right to any notice and hearing prior to the execution, levy, attachment or other type of enforcement of any judgment obtained hereunder, including, without limitation, the right to be notified and heard prior to the garnishment, levy, execution upon and attachment of Borrower’s bank accounts and other property. If a copy of this Note verified by affidavit of any officer of the Bank shall have been filed in such action, it shall not be necessary to file the original thereof as a warrant of attorney, any practice or usage to the contrary notwithstanding. The authority herein granted to confess judgment shall not be exhausted by any single exercise thereof, but shall continue and may be exercised from time to time as often as the Bank shall find it necessary and desirable and at all times until full payment of all amounts due hereunder and under any other Loan Documents. The Bank may confess one or more judgments in the same or different jurisdictions for all or any part of the Obligations arising hereunder or under any other Loan Documents to which Borrower is a party, without regard to whether judgment has theretofore been confessed on more than one occasion for the same Obligations. In the event that any judgment confessed against the Borrower is stricken or opened upon application by or on behalf of Borrower or any obligor for any reason, the Bank is hereby authorized and empowered to again appear for and confess judgment against Borrower for any part or all of the Obligations owing under this Note and/or for any other liabilities, as herein provided.

WAIVERS AND AMENDMENTS. No waivers, amendments or modifications of this Note and other Loan Documents shall be valid unless in writing and signed by an officer of Bank. No waiver by Bank of any Default shall operate as a waiver of any other Default or the same Default on a future occasion. Neither the failure nor any delay on the part of Bank in exercising any right, power, or remedy under this Note and other Loan Documents shall operate as a waiver thereof, nor shall a single or partial exercise thereof preclude any other or further exercise thereof or the exercise of any other right, power or remedy.

Except to the extent otherwise provided by the Loan Documents or prohibited by law, each Borrower and each other person liable under this Note waives presentment, protest, notice of dishonor, demand for payment, notice of intention to accelerate maturity, notice of acceleration of maturity, notice of sale and all other notices of any kind. Further, each agrees that Bank may (i) extend, modify or renew this Note or make a novation of the loan evidenced by this Note, and/or (ii) grant releases, compromises or indulgences with respect to any collateral securing this Note, or with respect to any Borrower or other person liable under this Note or any other Loan Documents, all without notice to or consent of each Borrower and other such person, and without affecting the liability of each Borrower and other such person; provided, Bank may not extend, modify or renew this Note or make a novation of the loan evidenced by this Note without the consent of the Borrower, or if there is more than one Borrower, without the consent of at least one Borrower; and further provided, if there is more than one Borrower, Bank may not enter into a modification of this Note which increases the burdens of a Borrower without the consent of that Borrower.

MISCELLANEOUS PROVISIONS. Assignment. This Note and the other Loan Documents shall inure to the benefit of and be binding upon the parties and their respective heirs, legal representatives, successors and assigns. Bank’s interests in and rights under this Note and the other Loan Documents are freely assignable, in whole or in part, by Bank. In addition, nothing in this Note or any of the other Loan Documents shall prohibit Bank from pledging or assigning this Note or any of the other Loan Documents or any interest therein to any Federal Reserve Bank. Borrower shall not assign its rights and interest hereunder without the prior written consent of

Bank, and any attempt by Borrower to assign without Bank’s prior written consent is null and void. Any assignment shall not release Borrower from the Obligations. Applicable Law; Conflict Between Documents. This Note and, unless otherwise provided in any other Loan Document, the other Loan Documents shall be governed by and construed under the laws of the state named in Bank’s address on the first page hereof without regard to that state’s conflict of laws principles. If the terms of this Note should conflict with the terms of any loan agreement or any commitment letter that survives closing, the terms of this Note shall control. Borrower’s Accounts. Except as prohibited by law, Borrower grants Bank a security interest in all of Borrower’s accounts with Bank and any of its affiliates. Swap Agreements. All swap agreements (as defined in 11 U.S.C. § 101, as in effect from time to time), if any, between Borrower and Bank or its affiliates are independent agreements governed by the written provisions of said swap agreements, which will remain in full force and effect, unaffected by any repayment, prepayment, acceleration, reduction, increase or change in the terms of this Note, except as otherwise expressly provided in said written swap agreements, and any payoff statement from Bank relating to this Note shall not apply to said swap agreements unless expressly referred to in such payoff statement. Jurisdiction. Borrower irrevocably agrees to non- exclusive personal jurisdiction in the state named in Bank’s address on the first page hereof. Severability. If any provision of this Note or of the other Loan Documents shall be prohibited or invalid under applicable law, such provision shall be ineffective but only to the extent of such prohibition or invalidity, without invalidating the remainder of such provision or the remaining provisions of this Note or other such document. Notices. Any notices to Borrower shall be sufficiently given, if in writing and mailed or delivered to the Borrower’s address shown above or such other address as provided hereunder, and to Bank, if in writing and mailed or delivered to Wachovia Bank, National Association, Mail Code VA7628, P. O. Box 13327, Roanoke, VA 24040 or Wachovia Bank, National Association, Mail Code VA7628, 10 South Jefferson Street, Roanoke, VA 24011 or such other address as Bank may specify in writing from time to time. Notices to Bank must include the mail code. In the event that Borrower changes Borrower’s address at any time prior to the date the Obligations are paid in full, Borrower agrees to promptly give written notice of said change of address by registered or certified mail, return receipt requested, all charges prepaid. Plural; Captions. All references in the Loan Documents to Borrower, guarantor, person, document or other nouns of reference mean both the singular and plural form, as the case may be, and the term “person” shall mean any individual, person or entity. The captions contained in the Loan Documents are inserted for convenience only and shall not affect the meaning or interpretation of the Loan Documents. Advances. Bank may, in its sole discretion, make other advances which shall be deemed to be advances under this Note, even though the stated principal amount of this Note may be exceeded as a result thereof. Posting of Payments. All payments received during normal banking hours after 2:00 p.m. local time at the office of Bank first shown above shall be deemed received at the opening of the next banking day. Joint and Several Obligations. If there is more than one Borrower, each is jointly and severally obligated. Fees and Taxes. Borrower shall promptly pay all documentary, intangible recordation and/or similar taxes on this transaction whether assessed at closing or arising from time to time. LIMITATION ON LIABILITY; WAIVER OF PUNITIVE DAMAGES. EACH OF THE PARTIES HERETO, INCLUDING BANK BY ACCEPTANCE HEREOF, AGREES THAT IN ANY JUDICIAL, MEDIATION OR ARBITRATION PROCEEDING OR ANY CLAIM OR CONTROVERSY BETWEEN OR AMONG THEM THAT MAY ARISE OUT OF OR BE IN ANY WAY CONNECTED WITH THIS AGREEMENT, THE LOAN DOCUMENTS OR ANY OTHER AGREEMENT OR DOCUMENT BETWEEN OR AMONG THEM OR THE OBLIGATIONS EVIDENCED HEREBY OR RELATED HERETO, IN NO EVENT SHALL ANY PARTY HAVE A REMEDY OF, OR BE LIABLE TO THE OTHER FOR, (1) INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES OR (2) PUNITIVE OR EXEMPLARY DAMAGES. EACH OF THE PARTIES HEREBY EXPRESSLY WAIVES ANY RIGHT OR CLAIM TO PUNITIVE OR EXEMPLARY DAMAGES THEY MAY HAVE OR WHICH MAY ARISE IN THE FUTURE IN CONNECTION WITH ANY SUCH PROCEEDING, CLAIM OR CONTROVERSY, WHETHER THE SAME IS RESOLVED BY ARBITRATION, MEDIATION, JUDICIALLY OR OTHERWISE. Patriot Act Notice. To help fight the funding of terrorism and money laundering activities, Federal law requires all financial institutions to obtain, verify, and record information that identifies each person who opens an account. For purposes of this section, account shall be understood to include loan accounts. FINAL AGREEMENT. This Note and the other Loan Documents represent the final agreement between the parties and may not be contradicted by evidence of prior, contemporaneous or subsequent oral agreements of the parties. There are no unwritten oral agreements between the parties.

WAIVER OF JURY TRIAL. TO THE EXTENT PERMITTED BY APPLICABLE LAW, EACH OF BORROWER BY EXECUTION HEREOF AND BANK BY ACCEPTANCE HEREOF, KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVES ANY RIGHT EACH MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION BASED ON, OR ARISING OUT OF, UNDER OR IN CONNECTION WITH THIS NOTE, THE LOAN DOCUMENTS OR ANY AGREEMENT CONTEMPLATED TO BE EXECUTED IN CONNECTION WITH THIS NOTE, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF ANY PARTY WITH RESPECT HERETO. THIS PROVISION IS A MATERIAL INDUCEMENT TO BANK TO ACCEPT THIS NOTE. EACH OF THE PARTIES AGREES THAT THE TERMS HEREOF SHALL SUPERSEDE AND REPLACE ANY PRIOR AGREEMENT RELATED TO ARBITRATION OF

DISPUTES BETWEEN THE PARTIES CONTAINED IN ANY LOAN DOCUMENT OR ANY OTHER DOCUMENT OR AGREEMENT HERETOFORE EXECUTED IN CONNECTION WITH, RELATED TO OR BEING REPLACED, SUPPLEMENTED, EXTENDED OR MODIFIED BY, THIS NOTE.

IN WITNESS WHEREOF, Borrower, on the day and year first above written, has caused this Note to be executed under seal.