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Background and Objectives: Translocator protein 18 kDa (TSPO) PET imaging is used to monitor glial activation. Recent studies have proposed TSPO PET as a marker of the epileptogenic zone (EZ) in drug-resistant focal epilepsy (DRFE). This study aims to assess the contributions of TSPO imaging using [ 18 F]DPA-714 PET and [ 18 F]FDG PET for localizing the EZ during presurgical assessment of DRFE, when phase 1 presurgical assessment does not provide enough information., Methods: We compared [ 18 F]FDG and [ 18 F]DPA-714 PET images of 23 patients who had undergone a phase 1 presurgical assessment, using qualitative visual analysis and quantitative analysis, at both the voxel and the regional levels. PET abnormalities (increase in binding for [ 18 F]DPA-714 vs decrease in binding for [ 18 F]FDG) were compared with clinical hypotheses concerning the localization of the EZ based on phase 1 presurgical assessment. The additional value of [ 18 F]DPA-714 PET imaging to [ 18 F]FDG for refining the localization of the EZ was assessed. To strengthen the visual analysis, [ 18 F]DPA-714 PET imaging was also reviewed by 2 experienced clinicians blind to the EZ location., Results: The study included 23 patients. Visual analysis of [ 18 F]DPA-714 PET was significantly more accurate than [ 18 F]FDG PET to both, show anomalies (95.7% vs 56.5%, p = 0.022), and provide additional information to refine the EZ localization (65.2% vs 17.4%, p = 0.019). All 10 patients with normal [ 18 F]FDG PET had anomalies when using [ 18 F]DPA-714 PET. The additional value of [ 18 F]DPA-714 PET seemed to be greater in patients with normal brain MRI or with neocortical EZ (especially if insula is involved). Regional analysis of [ 18 F]DPA-714 and [ 18 F]FDG PET provided similar results. However, using voxel-wise analysis, [ 18 F]DPA-714 was more effective than [ 18 F]FDG for unveiling clusters whose localization was more often consistent with the EZ hypothesis (87.0% vs 39.1%, p = 0.019). Nonrelevant bindings were seen in 14 of 23 patients in visual analysis and 9 patients of 23 patients in voxel-wise analysis., Discussion: [ 18 F]DPA-714 PET imaging provides valuable information for presurgical assessments of patients with DRFE. TSPO PET could become an additional tool to help to the localization of the EZ, especially in patients with negative [ 18 F]FDG PET., Trial Registration Information: Eudract 2017-003381-27. Inclusion of the first patient: September 24, 2018., Classification of Evidence: This study provides Class IV evidence on the utility of [ 18 F]DPA-714 PET compared with [ 18 F]FDG PET in identifying the epileptic zone in patients undergoing phase 1 presurgical evaluation for intractable epilepsy., (© 2023 American Academy of Neurology.)

Objectives: A decrease of [(18)F]fluoro-l-dopa uptake in basal ganglia was recently reported in medically refractory epilepsy. The purpose of this study was to assess the involvement of dopaminergic neurotransmission in refractory temporal lobe epilepsy (TLE) and its relationship to glucose metabolism and morphologic changes., Methods: Twelve TLE patients were studied using [(18)F]fluorodeoxyglucose PET, [(18)F]fluoro-l-dopa PET, and MRI and compared with healthy control volunteers. Morphologic cerebral changes were assessed using voxel-based morphometry. Student t test statistical maps of functional and morphologic differences between patients and controls were obtained using a general linear model., Results: In TLE patients, [(18)F]fluoro-l-dopa uptake was reduced to the same extent in caudate and putamen in both cerebral hemispheres as well as in the substantia nigra (SN). These dopaminergic functional alterations occurred without any glucose metabolism changes in these areas. The only mild morphologic abnormality was found in striatal regions without any changes in the SN., Conclusion: The present study provides support for dopaminergic neurotransmission involvement in temporal lobe epilepsy. The discrepancies between gray matter volume atrophy and the pattern of [(18)F]fluoro-l-dopa suggest that basal ganglia involvement is not related to structural subcortical abnormalities. A functional decrease can be ruled out because there was no change of the glycolytic pathway metabolism in these areas.

Objective: To test the hypothesis that extratemporal neuronal networks are involved in dystonic posturing (DP) observed in mesial temporal epilepsy (MTLE)., Methods: The authors analyzed electroclinical findings in 36 patients with MTLE with or without DP. Three DP types were defined (types I, II, III) corresponding to a gradual increase in duration and complexity. Interictal [18F]fluorodeoxyglucose-PET in different groups and subgroups was compared with control subjects using statistical parametric mapping software (SPM99)., Results: DP was found in 20 patients (55%), contralateral to the epileptogenic focus in 95%. Patients with DP had longer seizure duration, higher frequency of head deviation, salivation, motor manifestations, secondary generalization, severe clouding of consciousness, and prolonged postictal confusion when compared with patients without DP. Ictal discharge patterns during DP consisted of fast rhythmic activity spreading to frontal or suprasylvian areas, whereas slow rhythmic activity restricted to the temporal areas occurred in the absence of DP. In patients with DP, widespread temporal and extratemporal hypometabolism including the putamen was found. Hypometabolism was restricted to the anteromesial part of the temporal lobe and anterior insula in patients without DP. Putaminal hypometabolism was found in all DP types, but different extratemporal cortical involvements were found in DP subgroups: insula and inferior frontal gyrus in type I, inferior and superior frontal gyri and anterior cingulate gyrus in type II, and parietal areas in type III., Conclusion: Dystonic posturing may result from involvement of both putaminal and extratemporal cortical areas. Moreover, different frontal or parietal networks may be involved according to the duration or complexity of dystonic posturing.