Single photon emission computed tomography (SPECT) is a noninvasive technique used to create very clear, three-dimensional pictures of a major organ (e.g., the heart) by measuring blood flow through the organ. This test is very useful to help diagnose coronary artery disease.

SPECT scans use radionuclide imaging – a technique that involves the injection of very small amount of a radioactive substance called a tracer. Energy from the tracer in the body is detected by a gamma ray camera, which takes pictures that are reconstructed by a computer. A tracer is not a dye (contrast medium).

People may experience some slight discomfort from the needle used to insert an intravenous (I.V.) line in the crook of their arm, which is necessary to give the patient the tracer. Otherwise, these tests are painless.

Although the tracer is flushed harmlessly from the bodies of most individuals in about 48 hours, there are some people (e.g., pregnant or breastfeeding women) who should not have a radionuclide test. Patients are encouraged to discuss with their physician any concerns they may have about radiation exposure.