A myocardial perfusion scan (also known as a thallium scan, MIBI scan, MPS or technetium scan) uses a camera and a small amount of a radioactive chemical to see how well blood flows to the myocardium (muscles of the heart).
Often this scan is performed after gentle exercise to see how the heart muscle responds under stress.
The test is divided into two parts: stress and rest. For the stress part, you will be given an injection of a small amount of isotope (radioactive substance) and be asked to exercise on an exercise bike or treadmill. Or, you may be given a drug that stimulates your heart to beat faster (this is useful if you cannot do much exercise).
A large camera, positioned close to your chest, picks up the gamma rays sent out by the isotope as it passes through your heart. The camera takes pictures of the different parts of your heart.
For the rest part, you will be given a small amount of isotope while you're resting. The camera will then take the same sort of pictures as before.
During the test, the staff will monitor your heart rate and check your blood pressure.
You may be offered this test if you haven't previously been diagnosed with CHD and you go to A&E with chest pain. If the doctors think your chest pain is caused by CHD this test may confirm the diagnosis.
The test can show blood flow patterns to the heart walls and see if and how badly the coronary arteries are blocked. A myocardial perfusion scan can also determine the extent of injury to the heart following a heart attack.