Magnetic resonance spectroscopy-guided biopsy of intracranial tumors

Brain biopsy has evolved significantly over the last 3 decades. Initially, computed tomography-guided freehand biopsies were performed before the development of stereotactic head frames. Magnetic resonance imaging and computed tomography-guided brain biopsies incorporated the use of stereotaxis, which preceded the advent of frameless neuronavigational systems. Frameless stereotaxy relies on preoperative images and can be subject to brain shift that occurs with cranial perforation. The introduction of intraoperative magnetic resonance has negated the concern for brain shift because the imaging is performed in near real time, which allows the clinician to dynamically alter the approach to the lesion being biopsied. With the ability to directly visualize the surgical site, the diagnostic rate for brain biopsy now has surpassed that which was possible with conventional stereotaxis. Diagnostic biopsy rates of 100% are achievable using intraoperative magnetic resonance guidance in combination with a skull-mounted trajectory guide. Alignment of the trajectory guide toward the target uses a novel technique called prospective stereotaxy, which does not rely on frame-based or frameless stereotaxy. Magnetic resonance spectroscopy is a noninvasive technique for measuring specific metabolites within brain tissue that can suggest whether the tissue in question is neoplastic in nature. It is anticipated that by combining the use of the trajectory guide with prospective stereotaxy and magnetic resonance imaging guidance, the diagnostic accuracy or brain biopsy will be enhanced further.