Regional relationships between focal hypofixation images in 123I-IMP single photon emission computed tomography and epileptic EEG foci in interictal periods in patients with partial epilepsy.

Single photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123)-p-iodoamphetamine were performed in interictal periods in 40 patients with partial epilepsies and normal X-ray CT findings, and the regional relationships between the SPECT abnormalities and interictal epileptic EEG foci were studied. Twenty-six patients (65%) had abnormal SPECT images consisting of one or more focal hypofixation images, i.e., zones of decreased regional cerebral blood flow, while the remaining 14 patients showed normal images. Nineteen (73%) of the 26 patients showed complete or partial regional agreement between the abnormal SPECT findings and the interictal epileptic EEG foci determined from EEGs recorded repeatedly during their clinical course, while the regional relationships with the EEG foci determined from the single EEG recorded just after the SPECT scans or a short interval after the scans showed a lower rate of agreement (13 of 21 patients, 61.9%). These results confirm the utility of SPECT scans in the regional diagnosis of epileptic foci.