Abstracts

Rationale: Spontaneous low frequency blood oxygen level dependent (BOLD) fluctuations (<0.1Hz) as measured by resting-state fMRI has been used to elucidate human brain networks in normal and various pathological states. We investigated the relationship between magnitude of global functional connectivity (fc) as measured by resting state fMRI (fcMRI) and intracranial EEG findings in two patients who received epilepsy surgery.Methods: Structural and functional images were acquired with a 3 Tesla MRI using 32-channel head coil before and after the surgery. Preprocessing of fcMRI data was conducted using SPM8 and in-house software developed with MATLAB as our previous study (Kaneoke et al,10.1109/ICCME.2012.6275600). We used cross-correlation function to calculate the mean functional connectivity between a voxel and all other voxels in the gray matter as regional global functional connectivity (rGC) at each voxel. Patients data were compared with the mean map for normal volunteers (106 males, 100 females).Results: Case 1: A 27-year old male has a 6-year history of focal tonic seizure in the right arm followed by right hemiconvulsion. Interictal scalp EEG showed repetitive small sharp waves on the bilateral parietal regions. MRI demonstrated no lesion. FcMRI showed significantly higher magnitude of rGC in the left primary sensory area, inferior parietal lobule, superior temporal gyrus, and bilateral amygdala. Intracranial EEG showed spike and wave bursts in the bilateral parietal lobes, especially in the left superior and inferior parietal lobules. After resection of a part of left superior parietal lobule where ictal discharges were recorded, fcMRI showed reduction of the magnitude of rGC in the left inferior parietal lobule, left temporal lobe, left thalamus, and left precuneus. Although fcMRI didn t show ictal onest zone, the patient s rGC map seemed to be normalized after the surgery. Case 2: A 46-year old female has a 42-year history of postural tonic and hypermotor seizures. Interictal scalp EEG showed sharp and waves predominantly on C4, F4. MRI demonstrated hyperintensity lesion in the right supplementary motor area and cingulate gyrus. FcMRI showed significantly higher rGC in the right supplementary motor area (SMA), corpus striatum, and anterior cingulate gyrus. Intracranial EEG demonstrated ictal onset around the MRI visible lesion. After resection of the lesion, follw-up fcMRI showed reduction of the rGC magnitude in the right SMA and corpus stratum, and increase of anterior and posterior cingulate gyrus where correspond to the default mode network. FcMRI suggested that the patient s rGC was getting normal.Conclusions: We consider that resting-state fcMRI may be a potential tool to explore epileptic network and epileptogenic regions as significantly higher global functional connectivity in presurgical evaluation. To clarify this possibility, further experiences and long-term follow up of these cases should be needed.