Sherrie C. Oberg, president and CEO of the microsphere drug developer Acusphere, will retire from her position as CEO to become the company’s executive chair.

According to the Tewksbury, Mass.-based company, the change, effective Wednesday, will reduce Oberg’s salary by 20 percent.

Acusphere reported that Oberg’s new role comes as a cost-saving measure in the wake of efforts to work with the FDA to develop a clinical trial for the approval of Imagify (perflubutane polymer microspheres), an ultrasound imaging agent used in the detection of coronary artery disease.

With the position change, the company now expects its cash resources to extend through the third quarter of 2010.