Nuclear Cardiac Imaging

Radionuclide studies allow physicians to evaluate cardiac physiology and pathophysiology, including that of myocardial blood flow, myocardial metabolism, and ventricular function. A radionuclide cardiac perfusion study is a minimally invasive tool that uses small amounts of radioactive materials injected into the arm vein to create images of the heart.

The most commonly performed imaging procedure in nuclear cardiology is single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). The injected radioisotope is extracted from the blood by viable and working myocytes (but not by areas of ischemia or infarction) and retained within them for some time. Photons are emitted from the myocardium in proportion to the magnitude of tracer uptake, in turn related to perfusion. A gamma camera captures the emitted gamma ray photons and converts the information into digital data representing the magnitude of uptake and the location of the emission. The final result of SPECT imaging is the creation of multiple tomograms, or slices, of the heart, composing a digital display representing radiotracer distribution throughout the myocardium. With SPECT MPI, the display represents the distribution of perfusion throughout the myocardium. The heart’s pumping action and the extent and severity of coronary artery disease, including heart attacks, can thus be evaluated.

SPECT can give information about blood flow to tissues and chemical reactions (metabolism) in the body.

Radionuclide studies also help doctors assess chest pain (angina) and evaluate the success of bypass surgery or stent placement, among other things.