A single photon emission computed tomography (SPECT) scan is a type of nuclear imaging test that shows how blood flows to tissues and organs. A SPECT scan integrates two technologies to view your body: computed tomography (CT) and a radioactive material or tracer. The tracer allows doctors to see how blood flows to tissues and organs. Before the SPECT scan a patient is injected with the "tracer. A computer collects the information emitted by gamma rays and translates them into two-dimensional and three dimensional images for interpretation by a Nuclear Medicine radiologist.