Signa 1.5 tesla scanner

The locations of the electrodes were determined by clinical diagnosis. The electrodes (AdTech Medical Instrument Corporation, Racine, WI, United States) were positioned for subdural electrocorticography (ECoG) on the cortical surface (diameter of 4 mm, placed 10-mm apart) with stainless steel contacts. Prior to electrode implantation, each subject underwent a preoperative magnetic resonance imaging (MRI) scan in a Magnetom Trio, Magnetim Verio 3-tesla (Siemens, München, Germany) or Signa 1.5-Tesla scanner (GE, Boston, MA, United States). Computed tomography (CT) scans were performed following electrode implantation using a Somatom sensation device (64 eco; Siemens München, Germany). For visualization, CT and MRI images were co-registered as previously described (Avants et al., 2008 (link)). The brain model and implanted electrodes were reconstructed from individual preoperative MRI and postoperative CT images using CURRY software version 7.0 (Compumedics Neuroscan, Charlotte, NC, United States) (Figure 1). A neuroradiologist and neurosurgeon performed electrode localization based on thin-section post-implantation CT scans and co-registered MR images. BrainNet Viewer (Xia et al., 2013 (link)) was used to visualize the electrodes.

MRI was performed using a GE Signa 1.5-Tesla scanner (GE Medical Systems, Inc., Milwaukee, WI, USA) or a 3.0-Tesla scanner (Philips, Best, the Netherlands). All patients underwent the spoiled gradient echo, T2-weighted, and fluid attenuated inversion recovery imaging protocols.[20 (link)] The MRI results were classified as 5 subtypes: (a) unilateral HS, (b) bilateral HS, (c) unilateral HS and combined extra-hippocampal lesion (mainly ipsilateral anterior temporal atrophy or diffuse hemiatrophy/focal cerebromalacia), (d) normal, and (e) tumorous lesion involving mesial temporal structures.

MRI was performed using a GE Signa 1.5-Tesla scanner (GE Medical Systems, Inc., Milwaukee, WI, USA) or a 3.0-Tesla scanner (Philips, Best, the Netherlands). All patients underwent Spoiled Gradient Echo, T2-weighted and Fluid Attenuated Inversion Recovery imaging protocols. Also, MRI results were classified as lesional or non-lesional according to the presence of visible lesions with potential epileptogenicity.

T1-weighted MRIs of the brain were collected at the Unité de Neuroimagerie Fonctionelle, Université de Montréal, Canada (8 blind and 8 sighted controls), the MRI Lab, Fondazione Toscana ‘G. Monasterio’, Italy (11 blind and 11 sighted controls) and the DRCMR, Hvidovre University Hospital, Copenhagen, Denmark (9 blind and 9 sighted controls). The Montreal MRIs were acquired on a 1.5 Tesla magnet (Magnetom Avanto, Siemens, Erlangen, Germany), equipped with an 8-channel head coil, using a gradient echo pulse sequence (TR = 2240 ms, TE = 9.2 ms, FOV = 256 mm, matrix = 256×256, voxel size = 1 mm³). The Pisa MRIs were acquired on a GE Signa 1.5 Tesla scanner (General Electric Milwaukee, WI), equipped with a 2-channel head coil, using high resolution T1-weighted spoiled gradient echo (TR = 2270 ms, TE = 3.6 ms, FOV = 240 mm, matrix = 512×512, voxel size = 0.5×0.5×1 mm; resampled to 1 mm³). The Copenhagen MRIs were acquired on a Siemens Trio 3 Tesla magnet (Siemens, Erlangen, Germany), equipped with an 8-channel head coil, using a gradient echo pulse sequence (TR = 1540, TE = 3.9 ms; flip angle = 30°; FOV = 256 mm; matrix = 256×256; voxel size = 1 mm³).