Exercise thallium-201 myocardial scintigraphy

Ever since Pohost et al. discovered the redistribution phenomenon, exercise thallium-201 myocardial scintigraphy (Ex-SG) has been widely used and is indispensable for diagnosis and evaluation of ischemic heart disease. Initial exercise images should be obtained immediately after exercise ends and delayed images, four hours later. If perfusion defects appear in the exercise images but not in the delayed images, the condition is interpreted as transient myocardial ischemia ; whereas, the persistence of a defect in the delayed images generally represents irreversible myocardial damage. Ex-SG is shown to have higher sensitivity and specificity than exercise ECG for the detection of myocardial ischemia. Ex-SG is also useful for evaluation before and after coronary revascularization. It has been shown that some fixed defects may have viable muscle ; this is a problem especially in the decision about indications for revascularization surgery. The new technique of positron imaging is expected to produce more information in this area. (author) 82 refs