SPECT (single-photon emission computed tomography) shows the blood flow in the brain. A safe, very low-level radioactive substance is injected into your arm. The particles (very minute amounts) given off or emitted from the substance are measured. The more blood that flows through a certain area, the more particles are emitted. The result is displayed as a picture with different colors representing different levels of blood flow.

  • This test is readily available in most hospitals, but it is seldom needed as a routine test for epilepsy.  
  • SPECT scans obtained during or immediately after a seizure may show increased blood flow in the area where seizures arise. These can be helpful in finding where a seizure begins in the brain.
  • These tests can be misleading, however, especially when they are done between seizures.   
  • New computer techniques allow doctors to measure the differences between SPECT scans taken during and between seizures to obtain "subtraction" SPECT images.
  • These pictures can be used with a person's MRI to pinpoint the seizure focus. This technique also known as SISCOM may be most helpful when seizures begin outside the temporal lobe and MRI scans do not show a structural abnormality.   


Authored by: Ruben Kuzniecky, MD | Joseph I. Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/2013