Development and implementation of intraoperative magnetic resonance imaging and its neurosurgical applications

OBJECTIVE: We describe the development and implementation of a new open configuration magnetic resonance imaging (MRI) system, with which neurosurgical procedures can be performed using image guidance. Our initial neurosurgical experience consists of 140 cases, including 63 stereotactic biopsies, 16 cyst drainages, 55 craniotomies, 3 thermal ablations, and 3 laminectomies. The surgical advantages derived from this new modality are presented. METHODS: The 0.5-T intraoperative MRI system (SIGNA SP, Boston, MA), developed by General Electric Medical Systems in collaboration with the Brigham and Women's Hospital, has a vertical gap within its magnet, providing the physical space for surgery. Images are viewed on monitors located within this gap and can also be acquired in conjunction with optical tracking of surgical instruments, establishing accurate intraoperative correlations between instrument position and anatomic structures. RESULTS: A wide range of standard neurosurgical procedures can be performed using intraoperative MRI. The images obtained are clear and provide accurate and immediate information to use in the planning and assessment of the progress of the surgery. CONCLUSION: Intraoperative MRI allows lesions to be precisely localized and targeted, and the progress of a procedure can be immediately evaluated. The constantly updated images help to eliminate errors that can arise during frame-based and frameless stereotactic surgery when anatomic structures alter their position because of shifting or displacement of brain parenchyma but are correlated with images obtained preoperatively. Intraoperative MRI is particularly helpful in determining tumor margins, optimizing surgical approaches, achieving complete resection of intracerebral lesions, and monitoring potential intraoperative complications.