AMENDED AND RESTATED CHANGE OF CONTROL AGREEMENT

Exhibit 10.12

EXECUTION COPY

AMENDED AND RESTATED

CHANGE OF CONTROL AGREEMENT

AMENDED AND RESTATED CHANGE OF CONTROL AGREEMENT by and between Hologic, Inc., a Delaware corporation (the “Company”), and Patrick J. Sullivan (the “Executive”), dated as of August 17, 2007 (the “Agreement”). This Agreement amends and restates in its entirety that certain Change of Control Agreement dated as of May 20, 2007 (the “Original Agreement”) to further clarify certain provisions of the Original Agreement.

WHEREAS, upon the Closing Date (as such term is defined in the Merger Agreement) and pursuant to that certain Agreement and Plan of Merger by and among the Company, Nor’easter Corp. and Cytyc Corporation (“Cytyc”) dated as of May 20, 2007 (the “Merger Agreement”), the stockholders of Cytyc will own over 50% of the outstanding shares of the Company;

WHEREAS, subject to and conditioned upon the completion of the Merger, commencing as of the Closing Date (as defined in the Merger Agreement, such date to be sometimes referred to herein as the “Effective Time” of this Agreement), the Company desires that the Executive will serve as Executive Chairman and executive officer of the Company; and

WHEREAS, subject to and conditioned upon the consummation of the Merger (as such term is defined in the Merger Agreement), the Board of Directors of the Company (the “Board”), has determined that it is in the best interests of the Company and its shareholders to assure that the Company will have the continued dedication of the Executive, notwithstanding the possibility, threat, or occurrence of a Change of Control (as defined below) of the Company. The Board believes it is imperative to diminish the inevitable distraction of the Executive by virtue of the personal uncertainties and risks created by a pending or threatened Change of Control and to encourage the Executive’s full attention and dedication to the Company currently and in the event of any threatened or pending Change of Control, and to provide the Executive with compensation and benefits arrangements upon a Change of Control which ensure that the compensation and benefits expectations of the Executive will be satisfied and which are competitive with those of other corporations; and

WHEREAS, in the event that the Merger Agreement is terminated, then this Agreement shall become null and void ab initio and be of no further force and effect.

NOW, THEREFORE, in consideration of the mutual covenants and agreements hereinafter set forth, the parties hereto, each intending to be legally bound, do hereby agree as follows:

1. Certain Definitions .

(a) The “Effective Date” shall be the first date during the Change of Control Period (as hereinafter defined) on which a Change of Control occurs. Anything in this Agreement to the contrary notwithstanding, if the Executive’s employment

with the Company is terminated prior to the date on which a Change of Control occurs, and it is reasonably demonstrated that such termination of employment (1) was at the request of a third party who has taken steps reasonably calculated to effect the Change of Control or (2) otherwise arose in connection with or in anticipation of the Change of Control, then for all purposes of this Agreement the “Effective Date” shall mean the date immediately prior to the date of such termination of employment.

(b) The “Change of Control Period” is the period commencing on the date hereof and ending on the second anniversary of such date; provided, however, that commencing on the date one year after the date hereof, and on each annual anniversary of such date (such date and each annual anniversary thereof is hereinafter referred to as the “Renewal Date”), the Change of Control Period shall be automatically extended without any further action by the Company or the Executive so as to terminate three years from such Renewal Date; provided, however, that if the Company shall give notice in writing to the Executive, at least 60 days prior to the Renewal Date, stating that the Change of Control Period shall not be extended, then the Change of Control Period shall expire three years from the last effective Renewal Date.

2. Change of Control . For the purpose of this Agreement, a “Change of Control” shall mean:

(a) The acquisition by any one person, or more than one person acting as a group, of stock of the Company (the “Company Stock”) that, together with Company Stock held by such person or group, constitutes more than 50% of the total fair market value or total voting power of the Company Stock; provided, however, that if any one person, or more than one person acting as a group, is considered to own more than 50% of the total fair market value or total voting power of the Company Stock, the acquisition of additional Company Stock by the same person or persons shall be construed as not triggering a Change of Control; and provided further, however, that an increase in the percentage of Company Stock owned by any one person, or persons acting as a group, as a result of a transaction in which the Company acquires its Company Stock in exchange for property shall be treated as an acquisition of Company Stock for purposes of this Section 2(a);

(b) The acquisition by any one person, or more than one person acting as a group, on a single date or during the 12-month period ending on the date of the most recent acquisition by such person or persons, ownership of Company Stock possessing 30% or more of the total voting power of the Company Stock; provided, however, that if any one person, or more than one person acting as a group, already has satisfied this requirement, the acquisition of additional Company Stock by the same person or persons shall be construed as not triggering a Change of Control; and provided further, however, that an increase in the

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percentage of Company Stock owned by any one person, or persons acting as a group, as a result of a transaction in which the Company acquires its Company Stock in exchange for property shall be treated as an acquisition of Company Stock for purposes of this Section 2(b);

(c) A majority of the Company’s Board members is replaced during any 12-month period by directors whose appointment or election is not endorsed by a majority of the Company’s Board members before the date of the appointment or election; or

(d) The acquisition by any one person, or more than one person acting as a group, on a single date or during the 12-month period ending on the date of the most recent acquisition by such person or persons, assets from the Company that have a total gross fair market value equal to more than 40% of the total gross fair market value of all of the assets of the Company immediately prior to such acquisition or acquisitions; provided, however that there is no Change of Control under this Section 2(d) when there is a transfer to an entity that is controlled by the Company’s shareholders immediately after the transfer. For purposes of the immediately preceding clause, there is no Change of Control under this Section 2(d) if the assets are transferred to

For purposes of (i) through (iv) above, a person’s status generally is determined immediately after the transfer of the assets.

For purposes of this Section 2, persons shall not be considered as acting as a “group” solely because they purchase or own Company Stock at the same time, or as a result of the same public offering. However, persons shall be considered as acting as a “group” if they are owners of a corporation that enters into a merger, consolidation, purchase or acquisition of stock, or similar business transaction with the Company. If a person, including an entity, owns stock in the Company

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and another corporation that enter into a merger, consolidation, purchase or acquisition of stock, or similar transaction, such shareholder shall be considered to be acting as a “group” with other shareholders only with respect to the ownership in that corporation before the transaction giving rise to the change and not with respect to the ownership interest in the Company.

(e) Nothing herein shall supersede or effect the rights that the Executive may have under the Change of Control Agreement, as amended, entered into by and between the Executive and Cytyc with an effective date of July 23, 2003 (the “Cytyc Change of Control Agreement”); provided, however, that the Executive acknowledges that the benefits provided for under Section 2(a)(i)(B) therein were paid out upon consummation of the Merger.

3. Employment Period . Subject to and conditioned upon the consummation of the Merger and subject to the terms and conditions hereof, the Company hereby agrees to appoint Executive as Executive Chairman of the Board of Directors and to retain the Executive in its employ as an executive officer, and the Executive hereby agrees to accept such retention by the Company, for the period commencing on the Effective Date, and ending on the last day of the twenty-fourth month following the month in which the Effective Date occurs (the “Employment Period”).

4. Terms of Employment . (a)  Position and Duties . (i) During the Employment Period, (A) the Executive’s position (including status, offices, titles and reporting requirements), authority, duties and responsibilities shall be the same as those described in Exhibit A of the Amended and Restated Retention Agreement executed by and between the Company and Executive dated August 17, 2007 (the “Retention Agreement”) and (B) the Executive’s services shall be performed at the location of the Company’s corporate headquarters or any office or location less than 35 miles from such location.

(ii) During the Employment Period, and excluding any periods of vacation and sick leave to which the Executive is entitled, the Executive agrees to devote his full business time to the business and affairs of the Company and, to the extent necessary to discharge the responsibilities assigned to the Executive hereunder, to use the Executive’s reasonable best efforts to perform faithfully and efficiently such responsibilities. During the Employment Period it shall not be a violation of this Agreement for the Executive to (A) serve on corporate, civic or charitable boards or committees, (B) deliver lectures, fulfill speaking engagements or teach at educational institutions and (C) manage personal investments, so long as such activities do not significantly interfere with the performance of the Executive’s responsibilities as an employee of the Company in accordance with this Agreement. It is expressly understood and agreed that to the extent that any such activities have been conducted by the Executive prior to the Effective Date, the continued conduct of such activities (or the conduct of activities similar in nature and scope thereto) subsequent to the Effective Date shall be permitted.

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(b) Compensation .

(i) Base Salary . During the Employment Period, the Executive shall receive an annual base salary (“Annual Base Salary”) of Seven Hundred Thousand Dollars ($700,000.00). During the Employment Period, the Annual Base Salary shall be reviewed at least annually and shall be increased at any time and from time to time as shall be substantially consistent with increases in base salary awarded in the ordinary course of business to other peer executives of the Company and its affiliated companies. Any increase in Annual Base Salary shall not serve to limit or reduce any other obligation to the Executive under this Agreement. Annual Base Salary shall not be reduced after any such increase and the term Annual Base Salary as utilized in this Agreement shall refer to Annual Base Salary as so increased. As used in this Agreement, the term “affiliated companies” includes any company controlled by, controlling or under common control with the Company. Annual Base Salary shall be payable in accordance with the Company’s normal payroll practices, but shall be paid at least monthly.

(ii) Annual Bonus . In addition to Annual Base Salary, the Executive shall be awarded, for each fiscal year of the Company during the Employment Period, an annual bonus (the “Annual Bonus”) in cash at least equal to the greater of (a) the average (annualized for any fiscal year consisting of less than twelve full months or with respect to which the Executive has been employed by the Company or Cytyc for less than twelve full months) bonus (the “Average Annual Bonus”) paid or payable to the Executive by the Company and its affiliated companies or Cytyc, as applicable, in respect of the three fiscal years immediately preceding the fiscal year in which the Effective Date occurs, (b) the Annual Bonus paid for the fiscal year of the Company (if applicable, by Cytyc) immediately preceding the Effective Date, or (c) the maximum target bonus determined in accordance with the terms of the Company’s or Cytyc’s, as applicable, bonus plan for senior executives for the fiscal year immediately preceding the Effective Date (the “Target Bonus”). Each such Annual Bonus shall be paid no later than the 15th day of the third month of the fiscal year next following the fiscal year for which the Annual Bonus is awarded. In no event shall the calculation of the Annual Bonus, Average Annual Bonus and Special Bonus (as defined in Section 4(b)(iv)) include: any bonuses deferred by the Company, as applicable, or retention bonus or severance benefits provided under the Retention Agreement between the Executive and Company. Notwithstanding anything herein to the contrary, any portion of Annual Base Salary or Annual Bonus electively deferred by the Executive pursuant to a qualified or a non-qualified plan including, but not limited to, the Hologic, Inc. Supplemental Executive Retirement Plan (“SERP”) shall be included in determining the Annual Base Salary, Annual Bonus and the Average Annual Bonus. If the fiscal year of any successor to this Agreement, as described by Section 11(c) herein, is different than the Company’s fiscal year at the time of the Change of Control, then the Executive shall be paid (i) the Annual Bonus that would have been paid upon the end of Company’s fiscal year ending after the Change of Control, and (ii) a pro-rata Annual Bonus for any months of service performed following the end of the Company’s fiscal year, but prior to the first day of the successor’s fiscal year immediately following the Change of Control. The Annual Bonuses thereafter shall be based on the successor’s first full fiscal year beginning after the Change of Control and successive fiscal years thereafter.

(iv) Special Bonus . In addition to Annual Base Salary and Annual Bonus payable as hereinabove provided, if the Executive remains employed with the Company and/or its affiliated companies through the first anniversary of the Effective Date, the Company shall

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pay to the Executive a special bonus (the “Special Bonus”) in recognition of the Executive’s services during the crucial one-year transition period following the Change of Control in cash equal to the sum of (A) the Executive’s Annual Base Salary and (B) the greater of (x) the Annual Bonus paid or payable (annualized for any fiscal year consisting of less than twelve full months or for which the Executive has been employed for less than twelve full months) to the Executive for the most recently completed fiscal year of the Company during the Employment Period, if any, and (y) the greater of (i) the Average Annual Bonus, (ii) the Annual Bonus paid for the fiscal year immediately preceding the Effective Date, or (iii) the Target Bonus (such greater amount hereafter referred to as the “Highest Annual Bonus”). Anything in this Agreement to the contrary notwithstanding, if the Executive’s employment is terminated under Section 6(d) herein prior to the first anniversary of the Effective Date, then the Company shall pay the Executive the Special Bonus as if he was employed on the first anniversary of the Effective Date. The Special Bonus shall be paid no later than 30 days following the first anniversary of the Effective Date or, if earlier, the Date of Termination.

(v) Incentive, Savings and Retirement Plans . In addition to Annual Base Salary and Annual Bonus payable as hereinabove provided, the Executive shall be entitled to participate during the Employment Period in all incentive, savings and retirement plans, practices, policies and programs applicable to other peer executives of the Company and its affiliated companies, but in no event shall such plans practices, policies and programs provide the Executive with incentive, savings and retirement benefits opportunities, in each case, less favorable, in the aggregate, than the most favorable of those provided by Company or, if applicable, Cytyc, for the Executive under such plans, practices, policies and programs as in effect at any time during the one-year immediately preceding the Effective Date, or, if more favorable to the Executive, those provided generally at any time after the Effective Date to other peer executives of the Company and its affiliated companies.

(vi) Welfare Benefit Plans . During the Employment Period, the Executive and/or the Executive’s family, as the case may be, shall be eligible for participation in and shall receive all benefits under welfare benefit plans, practices, policies and programs provided by the Company and its affiliated companies (including, without limitation, medical, prescription, dental, disability, salary continuance, employee life, group life, accidental death and travel accident insurance plans and programs) and applicable to other peer executives of the Company and its affiliated companies, but in no event shall such plans, practices, policies and programs provide benefits which are less favorable, in the aggregate, than the most favorable of such plans, practices, policies and programs of the Company in effect at any time during the one-year period immediately preceding the Effective Date, or, if more favorable to the Executive, those provided generally at any time after the Effective Date to other peer executives of the Company and its affiliated companies.

(vii) Expenses . During the Employment Period, the Executive shall be entitled to receive prompt reimbursement for all reasonable expenses incurred by the Executive upon submission of appropriate accountings in accordance with the most favorable policies, practices and procedures of the Company and its affiliated companies in effect at any time during the one-year period immediately preceding the Effective Date or, if more favorable to the Executive, as in effect at any time thereafter with respect to other peer executives of the Company and its affiliated companies.

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(viii) Fringe Benefits . During the Employment Period, the Executive shall be entitled to fringe benefits in accordance with the most favorable plans, practices, programs and policies of the Company and its affiliated companies in effect at any time during the one-year period immediately preceding the Effective Date or, if more favorable to the Executive, as in effect at any time thereafter with respect to other peer executives of the Company and its affiliated companies.

(ix) Office and Support Staff . During the Employment Period, the Executive shall be entitled to an office or offices of a size and with furnishings and other appointments, and to exclusive personal secretarial and other assistance, at least equal to the most favorable of the foregoing provided to the Executive by Company at any time during the one-year period immediately preceding the Effective Date or, if more favorable to the Executive, as provided at any time thereafter with respect to other peer executives of the Company and its affiliated companies.

(x) Vacation . During the Employment Period, the Executive shall be entitled to paid vacation in accordance with the most favorable plans, policies, programs and practices of the Company and its affiliated companies as in effect at any time during the one-year period immediately preceding the Effective Date or, if more favorable to the Executive, as in effect at any time thereafter with respect to other peer incentives of the Company and its affiliated companies.

(xi) Out-Placement . If the Executive is terminated without Cause or resigns for Good Reason (both as defined herein), then the Company shall provide the Executive with outplacement services through Crenshaw Associates, Inc. (or a comparable executive search firm of the Executive’s choice and within his sole discretion) or in the alternative, reimburse the Executive within fifteen (15) days of the Date of Termination for executive outplacement servic