Abstracts

Rationale: Intracranial EEG (icEEG) has much greater sensitivity and spatial resolution than scalp EEG but spatial coverage is limited. We aimed to simultaneously record intracranial EEG and fMRI to study the haemodynamic correlates of localised epileptic icEEG activity both over the whole brain and in local regions where the epileptic activity was recorded from. Methods: Two patients undergoing presurgical evaluation with icEEG (#1: 76 subdural contacts, #2: 66 subdural contacts and 2x6 contact depth electrodes) were scanned with a 1.5T scanner. We used a head RF-coil, low-SAR sequences (?0.1W/Kg head-average), and a highly reproducible external electrode cable configuration. Sixty four channels of icEEG was recorded with MR compatible equipment during fMRI. This protocol was specifically safety tested in-vitro with heating <0.1 C. We acquired 2x10min EPI acquisitions (TE/TR40/3000ms 38x2.5mm slices, 0.5mm gap, 3x3mm in-plane resolution) during rest. Standard artefact correction methods were applied to EEG and general linear models containing visually identified interictal epileptiform discharges (IEDs) were applied to the fMRI data. Significant correlations were investigated both over the whole brain and in a-priori defined volumes of interest (VOI) around the most epilpetic contacts.