Clinical evaluation and follow-up results for intraoperative magnetic resonance imaging in neurosurgery

OBJECTIVE: The use of intraoperative magnetic resonance imaging (MRI) in ne urosurgery has increased rapidly, and a variety of concepts have recently b een presented. Although the feasibility of the procedure has been demonstra ted repeatedly, no conclusive analysis of its effects on the surgical proce dures, the extent of tumor removal, and outcomes, or its possible problems, has been performed. METHODS: Of 242 operations performed with intraoperative MRI, 97 procedures for supratentorial glioma treatment were analyzed with respect to intraope rative imaging results and postoperative outcomes. Analysis of the images i ncluded assessment of imaging artifacts, image quality, and extent of tumor removal. Patients were monitored to determine radiological progression, su rvival times, postoperative complications, and morbidity rates. RESULTS: No intraoperative complications related to the imaging procedure w ere observed. Image quality was good or fair in 85.5% of the cases. Differe nt types of surgically induced imaging changes could be identified. In 56 c ases, resection was continued using navigation with intraoperative MRI data sets (rereferencing accuracy, 0.9 mm). For high-grade gliomas, the percent age of cases in which residual tumor was identified by MRI could be signifi cantly reduced from 62% intraoperatively to 33% postoperatively, which was paralleled by a significant increase in survival times for patients without residual tumor. Complication and morbidity rates were within the ranges re ported for other studies. CONCLUSION: Intraoperative MRI is safe and allows reliable updating of neur onavigational data, with compensation for brain shifting. Surgically induce d imaging changes, which have been identified as a possible problem with in traoperative MRI in general, necessitated comparisons with preoperative sca ns and require future attention. The extent of tumor removal and survival t imes were increased significantly. Overall, patients seemed to benefit from the method.