SPECT (SINGLE POSITRON EMISSION COMPUTERIZED TOMOGRAPHY)
SPECT is a study that measures blood flow in the brain. This study is most sensitive when performed during the actual seizure (ictal SPECT). However, because the test must be performed during a seizure, it requires hospitalization equivalent to a phase I evaluation. The ictal spect measures regional increases in blood flow (hyperperfusion) in the brain during a seizure. Blood flow has been observed to increase in the area where the seizure begins. When seizure activity begins, trained and certified personnel administer the tracer, either technetium-99m ECD (ethyl cysteinate dimmer) or technetium-99m HMPAO (hexamethylpropylene amine oxime). In certain settings the test may help in localizing the area of seizure origin; timing of the injection is critical, however. If the tracer is injected more than 30 seconds after seizure onset, the results may be inconclusive.