Reproducibility of serial peri-ictal single-photon emission tomography difference images in epilepsy patients undergoing surgical resection

Peri-ictal single-photon emission tomography (SPET) difference images co-re gistered to magnetic resonance imaging (MRI) visualize regional cerebral bl ood flow (rCBF) changes and help localize the epileptogenic area in medical ly refractory epilepsy. Few reports have examined the reproducibility of SP ET difference image results. Epilepsy patients having two peri-ictal and at least one interictal SPET scan who later underwent surgical resection were studied. Localization accuracy of peri-ictal SPET difference images result s, interictal electroencephalography (EEG), and ictal EEG from the first (s eizure 1) and second (seizure 2) seizure, as well as MRI and positron emiss ion tomography (PET) findings, were compared using surgical resection site as the standard. Thirteen patients underwent surgical resection (11 tempora l lobe and 2 extratemporal), SPET results from seizure 1 were localized to the surgical site in 12/13 (92%) patients, while SPET results from seizure 2 were localized in 13/13 (100%) patients. All other modalities were less a ccurate than the SPET results [interictal EEG - seizure 1 6/13 (46%); ictal EEG - seizure 1 5/13 (38%); interictal intracranial EEG - seizure 2 4/9 (4 4%); ictal intracranial EEG - seizure 2 results 8/9 (89%); MRI 6/13 (46%); PET 9/13 (69%)]. SPET results were reproducible in 12/13 (92%) patients. SP ET difference images calculated from two independent peri-ictal scans appea r to be reproducible and accurately localize the epileptogenic area, While SPET difference images visualize many areas of rCBF change, the quantificat ion of these results along with consideration of injection time improves th e diagnostic interpretation of the results.