This test is used to determine if blood reaches the heart muscle from coronary arteries. Radioisotopes are radioactive elements like Cardiolite or Thallium. This test is combined with exercise stress test on the treadmill or a bicycle. This is to gently tire the heart and detect disease, which cannot be detected without exercise. In case the patient cannot walk, medicines are used to make the heart beat faster and put it under stress.
When the patient is near the highest target exercise, a very small amount of radioisotope is injected into the blood stream. The patient lies on scanning table which has a special camera on top. The camera detects whether radioisotope passes from the blood vessels to the heart muscle. This information is converted into images.
If after exercise, the heart muscle tissue does not receive enough radioisotopes, it means that part of the heart has less than adequate blood supply.
This result is recorded as images. This is then compared to the images of the heart at rest (without exercise).
The two series of images are compared by the cardiologist to determine if the heart muscle has deficient blood supply.