PET and SPECT in epilepsy.

Positron emission tomography (PET) measures regional cerebral metabolism and blood flow. PET imaging has been quite successful in identifying focal epileptogenesis as an area of hypometabolism between attacks. PET has proven to be an important diagnostic tool in selecting patients with partial epilepsy, in particular with foci in the temporal lobe, for resective surgery. Because of the high costs and complexities of PET, this technology has been confined to a limited number of centers. Single photon emission computed tomography (SPECT) can also be used for noninvasive functional imaging of the brain because it demonstrates regional cerebral blood flow which is linked to cerebral metabolism. SPECT uses conventional and readily available equipment and radiopharmaceuticals. Emphasizing the outstanding UCLA experience with PET, the presently available data on the usefulness of these functional imaging techniques in the context of surgical treatment of the epilepsies are reviewed.