Hybrid method PET/MRI brain imaging with 18F-FDG in diagnosis of focal cortical dysplasia in patients with focal drug-resistant epilepsy.

Up to 30% of patients with epilepsy are resistant to therapy. On the leading causes of drug-resistant epilepsy in adults and children is focal cortical dysplasia (FCD). Complete resection of FCD leads to complete elimination of epileptic seizures in 60-70% of patients; however, detecting and determining the boundaries of FCD using MRI can be challenging and, in some cases, even impossible task. PET/MRI is a new hybrid diagnostic method that can be applied in cases of negative and uncertain MRI results, as well as when MRI and video EEG monitoring data are discordant. Analysis of the diagnostic capabilities of the hybrid brain PET/MRI method with 18F-FDG in detecting FCD in patients with drug-resistant epilepsy, and analysis of metabolic patterns in patients with FCD of various types and localization. Retrospective analysis of hybrid brain PET/MRI data with 18F-FDG from 23 patients with FCD was conducted; a comparison of PET/MRI data with MRI and video EEG monitoring was performed; an analysis of 18F-FDG hypometabolism patterns in patients with FCD of different types and localization was done. FCD was detected in 13 out of 23 patients (56,5%) using MRI and in 22 patients (95,6%) using hybrid PET/MRI with 18F-FDG. Of these, 6 patients (23%) were MRI-negative, and in three cases (13%) signs of FCD were identified on MRI upon repeated targeted reanalysis in the area of 18F-FDG hypometabolism. A small focal area of 18F-FDG hypometabolism was found in all observations with FCD located in the frontal lobe, in 75% of frontal FCD cases. In cases of temporal FCD, the hypometabolic zone was extensive and involved two ore more gyri in all cases. Among 13 operated patients, seizure freedom (Engel class I) at the time of publication was achieved in 11 cases (84,6%), and Engel class II outcome was registered in 1 patient (4,3%). The use of brain PET/MRI with 18F-FDG in patients with focal drug-resistant epilepsy allows for increased detection of FCD by 39% compared to MRI alone, including MRI-negative patients and patients with subtle structural abnormalities. Small, focal areas of 18F-FDG hypometabolism were most commonly observed in FCD located in the frontal lobes; in this regard, analysis of PET/MRI images in patients with suspected frontal lobe FCD requires special attention.