A set of brain images shows a nonseizure SPECT, a seizure SPECT and a subtraction SPECT coregistered to MRI.

These SPECT images show the blood flow in the brain of a person when there's no seizure activity (left) and during a seizure (middle). The subtraction SPECT coregistered to MRI (right) helps pinpoint the area of seizure activity by overlapping the SPECT results with brain MRI results.