Myocardial perfusion scintigraphy.

Myocardial perfusion scintigraphy (MPS) is the only widely available method of direct assessment of myocardial perfusion. It involves intravenous injection of small amounts of a radioactive tracer at peak stress, followed by imaging of the heart with a gamma camera. There are three commercially available tracers: thallium-201 and two technetium-labelled tracers, sestamibi and tetrofosmin. All three are distributed throughout the myocardium in proportion to regional flow; the available data do not indicate a superiority of one agent over another for perfusion.1 The technetium-labelled tracers enable electrocardiogram (ECG)gated perfusion data to be acquired and perfusion and function assessed from a single study.