What is a myocardial perfusion scan?

A myocardial perfusion scan is a type of nuclear medicine procedure. This means that a tiny amount of a radioactive substance, called a radionuclide (radiopharmaceutical or radioactive tracer), is used during the procedure to assist in the examination of the tissue under study. Specifically, the myocardial perfusion scan evaluates the heart's function and blood flow.

A radionuclide is a radioactive substance used as a "tracer," which means it travels through the bloodstream and is taken up (absorbed) by the healthy heart muscle tissue. On the scan, the areas where the radionuclide has been absorbed will show up differently from the areas that do not absorb it (due to decreased blood flow to the area or possible damage to the tissue from decreased or blocked blood flow).

A cardiac perfusion scan measures the amount of blood in your heart muscle at rest and during exercise. It is often done to find out what may be causing chest pain. It may be done after a heart attack to see if areas of the heart are not getting enough blood or to find out how much heart muscle has been damaged from the heart attack.

During the scan, a camera takes pictures of the heart after a special test medicine (radioactive tracer) is given through an IV. The tracer travels through the blood and into the heart muscle. As the tracer moves through the heart muscle, areas that have good blood flow absorb the tracer. Areas that do not absorb tracer may not be getting enough blood or may have been damaged by a heart attack.

Two sets of pictures may be made during a cardiac perfusion scan. One set is taken while you are resting. Another set is taken after your heart has been stressed, either by exercise or after you have been given a medicine. The resting pictures are then compared with the stress images.

This test is also known by other names including myocardial perfusion scan, myocardial perfusion imaging, thallium scan, sestamibi cardiac scan and nuclear stress test.