Clinical Evaluation Of ～(18)FDG PET Cerebral Imaging In Patternization, Focus Localization And Prognosis Prediction Of Epilepsy

Background and Objectives: Patients with intractable partial epilepsy resistant to conventional medical therapy can be benefited from surgical removal of a discrete seizure focus. Since epileptic foci represent functional abnormalities, which are not always related to anatomic changes, therefore, the accuracy of localization by conventional neuroimaging procedures such as CT and MRI is usually low. Electrophysiological measurements are sensitive and special to seizure disorders, but is severely limited by its poor spatial resolution. Positron Emission Tomography (PET) imaging with fluorodeoxyglucose (FDG) demonstrates decreased glucose metabolism during interictal period and increased metabolism during ictal period in epileptogenic lesions. However, PET is not yet widely used in China. The aims of our study are (1) to find out the relationship between FDG PET image pattern and epileptogenic focus localization, (2) to help surgeons select patients and plan operation and (3) to predict therapeutic effect.Methods: 73 patients (51M, 22F, av. 23.3y) with epilepsy and 20 controls (15M, 5F, av. 38.5y) were studied with PET FDG cerebral imaging. Visual and semiquantitative analyses (asymmetric index, AI, in ROI of the homologous cerebral regions, ratio of SUV in various cerebral areas to cerebellum) were used to analyze the images. MRI and PET FDG image fusion was done in some patients. 40 patients who underwent surgery were followed up (av. 6 months, 2-12 months) for. assessment of seizure control. Among them, PET FDG imagings were repeated in 8 patients post surgery. The efficacy of PET FDG for the localization of epileptogenic foci was compared with that of VEEG, MRI and invasive EEG. Relationship between the cerebral FDG metabolic pattern and surgical outcome were also evaluated.SUV= Radioactivity in lesion (MBq/g)/[Injection dose(MBq)/ Weight(g)]AI (%)=(SUV_LROI-SUV_RROI)/[(SUV_LROI+SUV_RROI/2]* 100%Results and Discussions:1. From 20 controls, the sequence of SUV in various brain regions from top to below was basal ganglia, frontal lobe, occipital lobe, parietal lobe, lateral temporal lobe, cerebellum, medial temporal structure and thalamus respectively. AI in various brain areas was 6%-18% (similar to the reported value). The diagnostic standard AI >15% was considered as abnormal and 10%-15% as equivocal.2. Metabolic abnormalities were found in all 73 patients FDG PET imaging. 72...