Presurgical Identification of the Central Sulcus Using GE EPI Sequences in Combination with 3D Reconstruction is a Useful and Easy Technique for Functional Identification of the Sensorimotor Cortex

Abstract

Functional magnetic resonance imaging (fMRI) is a noninvasive neuroimaging technique that enables the visualization of vascular changes originating in the cortex on the execution of a simple motor task. We aimed to assess the usefulness of sensorimotor fMRI using echo-planar imaging (EPI) techniques and assess its clinical usefulness in the identification of the central sulcus. We studied 32 candidates for neurosurgery who had centrally located space-occupying lesions with fMRI using EPI images with blood oxygen level-dependent (BOLD) gradient-echo (GE) sequences acquired on a 1.5T scanner while patients repeatedly opened and closed their hands. Statistical activation images (t images) corresponding to the movements of the right and left hands were compared using cancellation analysis. Three-dimensional reconstruction of the cranium and brain of each patient showed the relative position of the expansive lesion and of non-damaged cortical tissue. Reproducible and selective functional sensorimotor activation was observed in 32 patients. Validation was carried out by intraoperative mapping in 19 patients. Based on intraoperative confirmation data we assumed that functional MR imaging (fMRI) is a valid method for identifying the motor cortex. Nevertheless, a limitation to our study is that not all the patients received invasive cortical stimulation. It is also relevant to indicate that fMRI and intraoperative procedures coincide in the sulcus identified as the sensorimotor cortex. Neurological examination did not reveal postoperative motor/sensitive deterioration in the remaining patients. fMRI using GE EPI sequences in combination with three-dimensional reconstruction is a useful and easy technique for functional identification of the sensorimotor cortex.