Nuclear scans have been used to diagnose heart disease for a long time. There are a variety of scans, including the MUGA (multiple-gated angiography) scan, the thallium scan, the sestamibi scan, and the PET (positron emission tomography) scan. These terms all refer to different types of nuclear agents that can be used to assess heart muscle performance and reveal the flow of blood into or out of the heart. By detecting the presence, severity, or impact of arterial disease, these studies can help determine whether or not a patient can be improved through the use of medical or surgical therapies. Finally, physicians may use nuclear scans to follow a patient's progress after a successful intervention such as bypass surgery or angioplasty, or to look for any toxic effects of chemotherapy.

	Nuclear scans can help reveal the presence and extent of arterial disease.

Nuclear cardiac scans are performed by injecting a radioactive chemical, or tracer, into a superficial vein in the arm that supplies easy access to the vascular system. The tracer circulates through the blood and into the heart. (This tracer is not related to the tracer used for CT or MR scanning.) Once it reaches the heart, the tracer can be absorbed either by the heart muscle or by red blood cells circulating through the heart. Tracer taken up by heart muscle reveals the pattern of blood absorption by the heart. Tracer attached to circulating red blood cells shows the action of the heart in squeezing and ejecting those cells. Certain types of nuclear scans focus on highlighting muscular function in terms of contraction, while others compare regional differences. Since coronary artery disease typically appears asymmetrically in the vascular system, nuclear scans often reveal only the region of the heart that is most affected.