What is a thallium scan (nuclear scan)?
A thallium nuclear scan is used to determine how well blood flows to the heart muscle. It’s usually performed in conjunction with an exercise stress test on a treadmill or bicycle. After reaching his or her maximum level of exercise, a small amount of thallium, a radioactive material, is injected into the patient’s bloodstream. The thallium mixes into the patient’s blood, and is carried to the heart. The thallium in the patient’s bloodstream can be seen and photographed using a special device called a gamma camera. Photographs are taken after the exercise test and show blood flow to the heart during exercise. Another series of photographs are taken when the patient is resting, and these are then compared to the photographs taken after exercising. These show blood flow to the heart muscle during rest.
