Intraoperative neurophysiological monitoring in low-field MRI environment

Abstract

Objective To evaluate methodological aspects and preliminary clinical experience in 9 patients for intraoperative neurophysiological monitoring(IOM)in low-field intraoperative MRI(iMRI) system.Methods Data of 9 patients with intracerebral neoplasms in eloquent areas underwent tumor resection assisted by both iMRI and IOM were reviewed.Before the maglmt was brought out from the cabinet.we got the baselineIOM waveform in order to compare with the wavoform within iMRI environment. Meanwhile.adverse effects caused by electrical stimulation and image distortions of iMRl were recorded.Early high-field MRI was performed to evalante the tumor resection after the operation.Results Combined use of iMRI and direct electrical stimulation (DES) Was performed in all patients.IOM could be performed with good quality within a low-field iMRI environment.However.a preamplifier was damaged during the monitoring in 1 case for magnetoelectric effect.The damage caused by heat or electrode movement was not observed.For image quality,signal voids were observed in the image areas which were very close to the scalp electrodes in 7 patients.Further tumor resection was performed in 3 patients for residual tumor demonstrated by iMRI.The completion of presurgical planning was achieved in all cases(7 total resection.2 subtotal resection).The iMRI findings were consistent with postoperative hish-field imaging in all cases.Conclusions IOM can be performed with standard quality within a low-field iMRI environment.The combined use of low-field open iMRI and IOM allows tumor resection control and continuous functional monitoring. Key words: Brain neoplasm; Intraoperative monitoring; Intraoperative magnetic resonance imaging; Electrical stimulation