“…We implemented our proposed procedure using a volume rendering algorithm [24] , a technique for building the scalp and cortical envelopes from MRI scans [25] , and a 3D electromagnetic digitizer (Polhemus Fastrak, Vermont, USA, [26] ). Both 2D and 3D visualizations of a high spatial resolution MRI volume facilitate the identification of the hidden cortical structures under the scalp and the visualization of the tangible real anatomical landmarks in the scanned volume.…”