Abstracts

Rationale: We retrospectively evaluated the diagnostic value of 18F-2-fluorodeoxy-D-glucose positron emission tomography (FDG-PET) with statistical analysis for the epileptic foci detection and predictive utility for postsurgical seizure outcome of patients with mesial temporal lobe epilepsy (mTLE).Methods: We evaluated 40 patients who were diagnosed mTLE and underwent selective amygdalohippocampectomy (SAH) or anterior temporal lobectomy (ATL) in our institute. Preoperative interictal FDG-PET with statistical analysis using three-dimensional stereotactic surface projection (3D-SSP) was detected with several clinical data including seizure semiology, MRI findings, scalp electroencephalography (EEG), surgical procedure with SAH or ATL and postsurgical outcome by ILAE classification. The region of interest (ROI) was put on hippocampus, amygdala, parahippocampal gyrus, uncus, T1, T2, T3 and fusiform gyrus. We obtained the ratio of hypometabolism difference (RHD) by statistical analysis using 3D-SSP, and evaluated the relation among extent of hypometabolic area, surgical outcome and surgical procedure.Results: RHD in each kind of ROIs in temporal lobe ipsilateral to surgical side was significantly higher than that of contralateral side in good surgical outcome groups. Hypometabolism of hippocampus and amygdala are most reliable prognostic factors. Patients of non-concordant with presurgical laterality examinations hardly have obvious lateralized hypometabolism. Nevertheless when they have significantly high RHD in mesial temporal lobe, good surgical outcome is expected. RHD did not show significant difference in any kind of ROIs between SAH and ATL group of good outcome.Conclusions: Significant hypometabolism in mesial temporal lobe on FDG-PET with 3D-SSP is useful to predict good surgical outcome of patients with mTLE. It is extremely beneficial for patients with hypometabolism in mesial temporal lobe structure even they are not concordant with presurgical laterality examinations. However, FDG-PET is not conclusive to decide surgical procedure extension from SAH to ATL.