Clinical impact of intraoperative magnetic resonance imaging on central nervous system neoplasia

Despite the introduction of neuronavigation, radicality is still an issue in operations for central nervous system neoplasia leading to integration of intraoperative magnetic resonance imaging (iMRI). The aim of the current study was to evaluate its clinical impact with regard to its potential to increase radicality and prolong patient survival. An open MRI scanner (Magnetom Open 0.2 T) was installed in one of the neurosurgical operating rooms. Of 377 procedures performed, 197 microsurgical operations for intraparenchymal tumors were analyzed. Intraoperative images were analyzed with respect to image quality, identification of residual tumor, and update of navigation. The results were controlled with early postoperative high-field MRI. Progression-free and overall survival were determined by patient follow-up. There were no complications. Failure to obtain intraoperative images was noted in only 3%, whereas diagnostic yield was found to be 86.4%. In 21.9% of the procedures, radical resection was confirmed intraoperatively. In 145 cases, navigation could be updated with an accuracy of 1.1 ± 0.6 mm. In 63.5% of the operations, resection was continued with intraoperative images leading to significantly increased radicality assessed by early postoperative MRI. Patients with a radically removed tumor had significantly prolonged progression-free and overall survival. Intraoperative MRI is a safe method for identifying residual tumor and compensating for brain shift by updating navigational data. The percentage of radiologically radical resections could be increased significantly. However, with regard to the costs of iMRI, overall clinical impact remains to be determined and alternative methods, such as intraoperative ultrasound, investigated.