Functional neuronavigation using an interventional magnetic resonance imaging (iMRI) system

Abstract

Introduction Biopsy and resection of brain tumors in eloquent areas remain challenging tasks because of the potential risk of postoperative neurological deficits and, consequently, a severe deterioration of life quality Biopsy and resection of brain tumors in eloquent areas remain challenging tasks because of the potential risk of postoperative neurological deficits and, consequently, a severe deterioration of life quality. Currently, many intraoperative identifications of eloquent brain areas are still based on anatomical landmarks. It is well known, however, that there is no exact correspondence between functional areas and anatomical structures. In addition, these structures can be altered by the tumor and the perifocal edema. Functional magnetic resonance imaging (fMRI) is widely accepted as a reliable method for the non-invasive localization of eloquent areas. For interventional neurosurgical procedures with an open MR scanner, it is, therefore, highly desirable for the neurosurgeon to map preoperative fMRI results onto the oblique anatomical iMRI planes determined by a localization device. An excellent correlation between fMRI maps and invasive intraoperative electrophysiological stimulation has been shown in a few studies involving the sensorimotor cortex [1,2,3]. In the presented work, an existing interventional navigation system (LOCALITE) has been extended by an fMRI module to allow the integration of preoperative functional MR data into intraoperatively acquired 3D-MR data sets. The aim of our study was to evaluate the feasibility of this promising combination as a tool for improved neurosurgical navigation. Methods Out of a patient group selected for open MR-guided resection, eight patients with cerebral lesions close to the central sulcus were enrolled in this preliminary study Out of a patient group selected for open MR-guided resection, eight patients with cerebral lesions close to the central sulcus were enrolled in this preliminary study. The preoperative functional data were acquired on a 1.5 T scanner (Magnetom Vision, Siemens, Erlangen, Germany) using EPI (TR 4 sec, TE 66 ms, 128 x 128, FOV 23 cm, 60 NEX). The sensorimotor cortex activation was achieved with a finger tapping paradigm. For fMRI post processing, the Siemens software mripp was used. Anatomical reference images were recorded with T1 weighting (TR 448 ms, TE 15 ms). These images are inherently registered with the EPI data set and serve as a basis for fMRI–iMRI mapping. Intraoperative imaging was performed on an open MRI scanner (Signa SP, 0.5 T, GEMS, Milwaukee, WI) equipped with a hand-held localization device (Flashpoint, IGT, Boulder, CO). Conventional neuronavigation with this …

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