Intraoperative MRI and Image-guided Frameless Neuronavigation

Neurosurgeons have long used various image-guided systems, such as fluoroscopy, ultrasound, and threedimensional (3-D) stereotaxy in an attempt to more accurately localize intracranial targets (34). The development of advanced neuroimaging techniques over the years has provided the neurosurgeon with increasingly more accurate and precise tools to aid in the microsurgical treatment of intracranial lesions, such as intrinsic brain neoplasms. Studies have shown that, without the aid of image guidance, as many as 80% of operations performed to remove brain tumors leave part of the lesion behind (16). Although difficult to prove definitively, many recent papers have reported that the degree of resection of gliomas apparently correlates with both progression-free and overall survival (4, 7, 8, 17, 18, 20, 25, 26, 28, 48, 50). Consequently, real-time intraoperative information regarding the anatomic characteristics of the surgical field remains an important consideration to the neurosurgeon.