11C-flumazenil PET in neocortical epilepsy

Objective: To investigate focal cortical abnormalities of gamma-aminobutyric acid type A-central benzodiazepine receptors (GABA(A)-cBZRs) in patients with extratemporal partial seizures with acquired lesions and in patients with normal high-resolution MRI. Methods: Six patients with acquired lesions and 18 patients with normal high-resolution MRI and extratemporal partial seizures, as well as 24 normal controls, were studied with (11)C-flumazenil (FMZ) PET to produce voxel-by-voxel images of FMZ volume of distribution (FMZVD), which reflects density of GABA(A)-cBZRs. These images were analyzed using Statistical Parametric Mapping (SPM). Each patient was compared with the control group to reveal regions with abnormal FMZVD at p < 0.001 uncorrected, corrected to p < 0.05 for the whole brain volume. Each normal control was compared with the remaining controls in the same manner. Results: All six patients with acquired lesions had a single region of reduced FMZVD. Thirteen of 18 patients with normal MRI had regions of abnormal cortical FMZVD: 10 had regions of increased FMZVD, 6 had regions of decreased FMZVD, and 3 had both regions of increased and decreased FMZVD. Seven patients had an abnormality in the lobe and 12 in the hemisphere of presumed seizure origin. Conclusions: FMZ PET analyzed with SPM is an automated, objective, sensitive, and specific means for detecting regional cortical abnormalities of GABA(A)-cBZRs in patients with partial seizures. This technique may be useful in the evaluation of patients with refractory partial seizures for surgical treatment, particularly in those patients with normal MRI.