Intraoperative imaging--MRI.

Neuronavigation has become a standard technique in many neurosurgical procedures where its use allow better positioning of the craniotomy flap, precise targeting of lesions, and better anatomical orientation. However, the imaging used in such procedures is acquired preoperatively and thus, cannot project the dynamic changes that occur during surgery and result in many cases in significant brain shift and decreased accuracy. Recent technological developments have yielded a variety of MRI machines that can be used intraoperatively and provide the surgeon with updated images, integrated navigation capabilities, full compensation for brain shifts, and the ability to assess the extent of resection of the lesion. The concepts behind such technologies vary from one manufacture to another resulting in systems that vary in complexity, ease of use, spatial demands, and cost. In this chapter we review our experience with two intraoperative MRI systems used in a variety of neurosurgical procedures: the GE Signa SP System and the Odin PoleStar System.