A nuclear stress test uses radioactive dye and an imaging machine to create pictures showing the blood flow to your heart. The test measures blood flow while you are at rest and are exerting yourself, showing areas with poor blood flow or damage in your heart.
The test usually involves injecting radioactive dye, then taking two sets of images of your heart — one while you're at rest and another after exertion.
A nuclear stress test is one of several types of stress tests that may be performed alone or in combination. Compared with an exercise stress test, a nuclear stress test can help better determine your risk of a heart attack or other cardiac event if your doctor knows or suspects that you have coronary artery disease.