PET

Serotonin 1A receptor imaging and temporal lobectomy. Robert Bonwetsch, MD, Giampiero Giovacchini, MD, Richard Carson, PhD, Patricia Reeves-Tyer, Kathy Kelley, MA, Peter Herscovitch, MD and William H Theodore, MD. Bethesda, Maryland.

Positron emission tomography (PET) may provide supportive data for detecting epileptogenic zones in patients with temporal lobe epilepsy (TLE), helping to reduce the need for invasive EEG studies. Serotonin (5HT) 1A receptor binding has been shown to be decreased in TLE. We used PET to compare 5HT-1A binding measured with the silent antagonist 18FCWAY, to glucose metabolism measured with 18FDG, in 19 patients who had temporal lobectomy for uncontrolled epilepsy, and a mean follow-up of 31 months. We analyzed PET data with co-registered MRI and partial volume correction, computing an asymmetry index (AI) using the formula [2] x [ipsilateral contralateral]/[ipsilateral + contralateral] for anatomic regions drawn on each patient s co-registered MRI scan. Mean FDG asymmetry in the resected region was 0.25 0.18, versus 0.47 0.20 for FCWAY (P<0.001). Three patients, including one with normal MRI, had unrevealing FDG PET but a clear FCWAY asymmetry. There was a trend for 13 patients who were seizure-free to have greater FCWAY (p<0.08), but not FDG AI, than 6 patients with persistent seizures. Our preliminary results suggest that FCWAY PET may be more sensitive than FDG for presurgical evaluation of temporal lobe epilepsy.