Compatibility of MRI and FDG-PET findings with histopathological results in patients with focal cortical dysplasia

PURPOSE The present study aimed to determine if the specific characteristics of fluorodeoxyglucose-positron emission tomography (FDG-PET) analyses of the FCD subgroups were compatible with the magnetic resonance imaging (MRI) and clinical findings of the patients in these subgroups. METHODS This study included 71 patients who had a presurgical evaluation workup performed due to drug-resistant seizures, who underwent epilepsy surgery, and who were histopathologically diagnosed with FCD. Relationships involving MRI and FDG-PET findings and clinical data from pathological subgroups and patients were assessed. RESULTS According to the International League Against Epilepsy (ILAE) classifications of FCD, 28 of the patients were type I and 43 were type II. FCD was visible on the MRI scans of 53 patients, and a majority of this group was classified as type II FCD (n=34). Of these 53 patients, FCD was located in the temporal area of 21 patients, the extratemporal area of 29 patients. Of the patients who exhibited FDG-PET hypometabolism (PET-positive), 23 were classified as temporal, 17 as frontal, 11 showed involvement of the posterior cortex. The age of seizure onset was younger in PET-positive patients (p=0.032), and histopathological analyses revealed that 23 patients had type I FCD and 30 patients had type II FCD. CONCLUSION PET scans reveal a lesion by showing hypometabolism in patients who have refractory epilepsy and an early age of onset with FCD. The lesions of MRI-negative/PET-positive FCD patients tend to be localized in the temporal lobe and that FCD may be localized in the frontal lobe of MRI-negative/PET-negative patients. However, the histopathological examinations of MRI-positive/PET-positive, MRI-negative/PET-positive, and MRI-negative/PET-negative patients did not exhibit a particular histopathological subtype.