Stratifying differences on ictal/interictal subtraction SPECT images.

Purpose: Subtraction of interictal from ictal single-photon emission computed tomography (SPECT) yields numerous foci that encompass a range of pixel values scattered in the brain. This preliminary study evaluated the significance of this range of values.

Methods: Subtraction images were obtained by registering, normalizing, and subtracting interictal from ictal SPECT for 13 patients.