What is it ?
'Thallium study' is a general term used for 'Stress myocardial perfusion scintigraphic study', a test which is aimed at viewing the distribution of blood to the heart muscle. The distribution varies between a patient with previous heart attack, a patient of angina and a normal individual. Thallium 201 (Tl201) and Technicium 99m (Tc99m)- radiopharmaceuticals are used for this study. These radiopharmaceuticals map the distribution of blood supply to the heart muscle when imaging is done using a Gamma Camera/SPECT.This is performed on exercise and at rest.

Before starting to exercise, the patient receives an injection of thallium 201, a radioactive chemical, which is taken up by normal heart muscle cells:

• Immediately after exercise, heart scans are performed.
• If muscle tissue is damaged by ischemia (oxygen deprivation), it will fail to take up thallium and will be detected on the scanned image
• If the scan detects damage, it is repeated two or three hours after exercise.
• Damage due to a prior heart attack will persist when the heart scan is repeated. Injury caused by angina, however, will have resolved by that time