PRESURGICAL MULTIMODALITY NEUROIMAGING IN ELECTROENCEPHALOGRAPHIC LATERALIZED TEMPORAL-LOBE EPILEPSY

The purpose of this study was to compare 2-[F-18] fluoro-2-deoxy-D-glu cose positron emission tomography (FDG-PET), hippocampal volumetry (HV ), T2 relaxometry, and proton magnetic resonance spectroscopic imaging (H-1-MRSI) in the presurgical neuroimaging lateralization of patients with nonlesional, electroencephalogram (EEG)-defined unilateral tempo ral lobe epilepsy (TLE). Twenty-five patients were prospectively studi ed, along with age-matched controls. T2 relaxometry examinations were performed in 13 patients. Comparison of FDG-PET, HV, and H-1-MRSI was possible in 23 patients. FDG-PET lateralized 87% of patients, HV 65%, N-acetyl aspartate (NAA)/(choline [Cho] + creatine [Cr]) 61%, and [NAA ] 57%. Combined HV and NAA/(Cho + Cr) results lateralized 83% of the p atients, a value similar to PET. Of 10 patients with normal magnetic r esonance imaging (MRI) scans, 2 were lateralized with HV, 6 with FDG-P ET, 4 with NAA/(Cho + Cr), and 3 with [NAA]. T2 relaxometry lateralize d no patients without hippocampal atrophy. Bilateral abnormality was p resent in 29 to 33% of patients with H-1-MRSI measures and 17% with HV . Only hippocampal atrophy correlated with postoperative seizure-free outcome. FDG-PET remains the most sensitive imaging method to correlat e with EEG-lateralized TLE. Both FDG-PET and H-1-MRSI can lateralize p atients with normal MRI, but only the presence of relative unilateral hippocampal atrophy is predictive of seizure-free outcome. Bilaterally abnormal MRI and H-1-MRSI measures do not preclude good surgical outc ome.