PET is a technique that shows the brain’s use of oxygen or sugar (glucose). As with SPECT, a very low, safe dose of a radioactive substance is injected into the patient’s arm and the scanner records its circulation. Not all types of PET scans look alike, but often different colors are used to show areas of higher or lower use of oxygen or sugar.
This test can help to identify the area of the brain from which partial seizures arise. It may be performed in the period between seizures, the interictal period. Unlike the SPECT, PET testing can be done on an outpatient basis, as it is not necessary to perform this test on a patient during or immediately after his or her seizure.
PET scans are expensive, and are needed in very few patients with epilepsy. Many insurance companies will pay for PET scans for patients who are being evaluated for epilepsy surgery.