Radionuclide Test (Stress Thallium)
Stress Thallium test, Radioisotope scan, myocardial perfusion scan (MPS), SPECT (single photon emission computed tomography), technetium scan, thallium scan, MIBI scan, or MUGA scan (multiple-gated acquisition scan).
Radionuclide tests are used for investigating coronary heart disease. They are less common than electrocardiograms or echocardiograms.
A doctor will inject a small amount of radioactive substance (isotope) into the blood, often while you are exercising on an exercise bike or treadmill (a running machine). You may be given a drug that stimulates your heart to beat faster and harder. This is particularly useful if you cannot do much exercise.
A large ‘camera’, positioned close to the chest, picks up the gamma rays sent out by the isotope as it passes through the heart. The camera can take different types of pictures of the heart depending on what sort of isotope is used. Different isotopes are used for different tests. These include technetium, tetrofosmin and thallium. In all these tests you get only a small dose of radioactivity.
What can the test show?
Depending on what sort of isotope is used, the camera can take pictures to:
- look at how strongly your heart pumps (usually a MUGA scan)
- look at the flow of blood to the muscular walls of the heart, or
- help diagnose coronary heart disease (usually a technetium or thallium scan).
PET (positron emission tomography) scans
This test involves having an injection of a small amount of radioactive material and then lying on a couch under a scanning device. You may need to lie still for up to two and a half hours. This test allows doctors to examine the flow of blood and see how your heart muscle is working. PET scans are useful in people who have complicated medical problems and who are being considered for surgery or angioplasty.