An Sv2a-Specific Pet Radiotracer F-18-Sdm Pet For The Localization Of Drug-Resistant Temporal Lobe Epilepsy

396 Purpose: Around 600 million people suffer from epilepsy worldwide, and 20 to 40 percent of them have intractable seizures. For refractory epilepsy, surgical treatment is a way to relieve seizures and achieve epilepsy free. Although 18F-FDG PET has been proved to be an effective technique for presurgical localization of epileptogenic zone, postoperative pathology and MRI showed the hypometabolic region is not completely related to the degree of hippocampal sclerosis for temporal lobe epilepsy. 18F-SDM PET is a synaptic vesicle glycoprotein 2A (SV2A) radioligand which shows the density of synapses in the brain, studies showed that SDM bonding was reduced in seizure onset zone of epilepsy subjects. The objective of this study was to investigate the diagnostic value of 18F-SDM-PET imaging in patients with temporal lobe epilepsy with hippocampal sclerosis compared with18F- FDG-PET. Methods: Ten patients clinically diagnosed as temporal lobe epilepsy with hippocampal sclerosis were examined for both 18F-FDG PET and 18F-SDM-PET. Semi-quantitative analysis and abnormal volume measurement were performed by two experienced PET/CT diagnosticians, and the presence of high or low synaptic/metabolic zones in two or more consecutive slices was defined as abnormal. Region-of-Interest (ROI) analysis of 18F-FDG PET images and parametric 18F-SDM PET images include the SUVmean value of bilateral medial temporal lobe region and bilateral hippocampal region, the asymmetry index (AI) and standardized uptake value ratio (SUVR) were calculated. SUVR=SUVmean of abnormal region/SUVmean of the same side cerebellum. The data were analyzed using the paired t-test by SPSS (IBM SPSS Statistics, Version 21.0). Statistical significance is defined as p ˂ 0.05. Results: In the visual assessment of PET images, the low uptake regions of parametric 18F-SDM more commonly located in the middle temporal region (mean:1.10±0.31) than that of 18F-FDG (mean:2.10±0.87, P=0.008). In the bilateral hippocampal region, there is no significant difference between 18F-FDG PET and 18F-SDM PET in AI (t=-0.461, p=0.655), but a significant difference in SUVR (t= -4.494, p=0.002). Besides, significant differences also showed in the bilateral temporal lobe region between FDG and SDM in AI (t=3.317, p=0.009) and SUVR(t=-5.897, p=0.001). Conclusions: In the preoperative assessment of drug-resistant TLE, 18F-SDM PET may be used as a clinical tool for the localization of epileptogenic zones, showing a more restricted region in the temporal lobe, providing additional information on abnormal areas for 18F-FDG PET. Acknowledgments: This study was supported by the National Natural Science Foundation of China, Grant No.81801740.