Conventional SPECT Versus 3D Thresholded SPECT Imaging in the Diagnosis of ADHD: A Retrospective Study.

Brain single photon emission CT (SPECT) scans indirectly show functional activity via measurement of regional cerebral blood flow. In conventional SPECT scans, the typical tomographic slices are produced. In three-dimensional thresholded SPECT scans, pixels representing activity below a certain threshold are discarded.