Abstracts

Rationale: FDG-PET is one of useful evaluations to localize the epileptic areas in patients with epilepsy. In order to utilize FDG-PET more for detecting epileptic focus and predicting therapeutic outcome, statistical analysis has been indicated comparing to normal database. In this paper, we evaluate whether FDG-PET with statistical analysis is useful for predicting seizure outcome. Methods: Patients with temporal lobe epilepsy treated at Juntendo University, Tokyo, Japan from 2006 to 2011 were enrolled in this study. They were 33, and evaluated interictal glucose metabolism using 18F-FDG-PET before surgery. After obtaining the glucose metabolism data, we performed statistical analysis (3D-SSP) using normal database. We evaluated them dividing into some areas of interest as followings, hippocampus, amygdala, uncus, parahippocampal, fusiform, T1, T2, and T3 gyruses. Areas of hypometabolism greater than 1.69 of Z-score were accepted as statistical significant. We analyzed the relationship between the percentage of significant ROI (%ROI) and seizure outcome (Engel's class I to class II~IV) in each area. We also analyzed the correlation between %ROI in the hippocampus to epileptic discharge (intraoperative EEG from the hippocampus) and pathological change (Watson's grading). Results: In good surgical outcome (Engel's class I) group, %ROIs in ipsilateral all area we interested were significantly greater than those of cotralateral side. In comparison between Engel's class I and II~IV, %ROI of Engel's class I group at all area except fusiform gyrus were greater with statistical significant. We also found correlation between %ROI in the hippocampus and pathological grading, but no relation between %ROI and intraoperative IEDs. Conclusions: FDG-PET using statistical analysis can predict the surgical outcome. Hypometabolism in mesial and lateral temporal lobe especially hippocampus and amygdala is a great predicator of good outcome. The hypometabolism in the hippocampus does not come from epileptic discharges but pathological damage of hippocampus.