What is a RADIONUCLIDE TEST (Nuclear medicine)?

The doctor injects a small amount of isotope (radioactive substance) into the patients blood. This may be done as part of an exercise test; in other words, the patient may be running on a treadmill or riding the stationary bicycle.

When a patient is unable to do physical exercise, the doctor will administer a drug that will cause the activity of the heart to increase and the flow of blood to increase to the heart.

During this test, a large camera is positioned over the patients chest. This camera picks up the gamma rays that are sent out by the isotope (radioactive substance) in the patients blood. This enables technicians and doctors to visualize the heart from the inside, showing how the heart fills and empties with blood, or it may demonstrate how blood flows to the muscular walls of the heart.

Various types of isotopes used include thallium, tetrofosmin, technetium MIBI and technetium. These isotopes break down rather quickly and therefore the patients exposure to the radioactive substance is very limited.

Radionuclide tests are very safe and very accurate as far as diagnosing if a patient has disease of the heart muscle. These tests are however used less frequently than ECG and Echocardiogram.

How do radionuclide tests benefit the diagnostic process?

The blood-flow to the heart muscle can be accurately assessed by means of radionuclide tests. It is a more specific and detailed test that provides more information regarding the heart muscle compared with an Exercise ECG. By using different isotopes, doctors are able to observe several different aspects pertaining to how the heart muscle is functioning. It is especially useful in providing information on the strength of the heart muscle.

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