Myocardial Perfusion Scintigraphy

Recent progress in diagnostic cardiology has centered around noninvasive methods^1,2; among these, echocardiography and myocardial scintigraphy have developed most rapidly.^3-6 Probably most prominent among the diverse scintigraphic methods is relative myocardial perfusion imaging.¹ The method employs an intracellular cation, most commonly thallium (TL) 201, administered in the form of thallous chloride. The TL 201 is rapidly extracted from the blood following a peripheral intravenous injection⁷ and is avidly taken up by the viable myocardium in proportion to relative coronary perfusion.^" Owing to the rapid extraction of these radionuclides and the transient stability of their localization, injection made during bicycle or treadmill exercise and imaging performed within a brief period following injection permit evaluation of myocardial perfusion present at the time of injection.^9-13 Image abnormalities present on the stress study can be compared with a subsequent image performed at rest or at redistribution, three to four