低场强术中磁共振环境下的神经电生理监测

Intraoperative neurophysiological monitoring in low-field MRI environment

目的探讨低场强iMRI环境下神经电生理监测（IOM）的操作特点与临床初步体会。方法分析9例功能区脑肿瘤IOM及iMRI的联合应用情况。采集IOM基线，与iMRI环境下的波形比较；记录iMRI影像畸变及电刺激相关不良事件。术后早期复查MRI评估肿瘤切除情况。结果9例行IOM均获得稳定波形。1例前置放大器因磁电效应损坏，未观察到热损伤或电极移动损伤。iMRI7例局部信号缺失；3例发现肿瘤残余。术后随访MRI7例全切，2例次全切除，与iMRI判断一致。结论低场强iMRI环境下，IOM可获得稳定波形。二者联合应用，有助于病变安全切除。

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 magnet was brought out from the cabinet, we got the ＂baseline＂ IOM waveform in order to compare with the waveform within iMRI environment. Meanwhile, adverse effects caused by electrical stimulation and image distortions of iMRI were recorded. Early high -field MRI was performed to evaluate 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 high- 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.