Low-field magnetic resonance imaging for intraoperative use in neurosurgery: a 5-year experience.

The aim of this study was to evaluate the feasibility and point out the indications of intraoperative MR imaging in neurosurgical procedures. The MR imaging was performed using a 0.2-T scanner which was located in a radiofrequency-shielded operating theater. Three major setups for intraoperative imaging were possible: inside the scanner; at the 5-Gauss line; or in an adjacent operating theater. Additionally, in lesions adjacent to eloquent brain areas microscope- and pointer-based neuronavigation with integrated functional data was applied. Three hundred ten patients were investigated in the previous 5 years, among them gliomas ( n=95), pituitary tumors ( n=81), and 39 non-lesional cases in whom resective or disconnective epilepsy surgery was carried out. We did not observe any adverse effects due to intraoperative MR imaging. Image quality was sufficient to evaluate the extent of the tumor resection in the majority of cases. The main indications for intraoperative MR imaging were the evaluation of the extent of a resection in glioma, ventricular tumor, pituitary tumor, and in epilepsy surgery. Intraoperative MR imaging offers the possibility of further tumor removal during the same surgical procedure in case of tumor remnants, increasing the rate of complete tumor removal. Furthermore, the effects of brain shift, which would lead to inaccurate neuronavigation, can be compensated for by an update of the neuronavigation system with intraoperative MR image data.