What is the primary purpose of a myocardial perfusion scan?

• A. Assess regional myocardial blood flow and identify areas of under-perfusion (ischemia or infarct).
• B. Measure ejection fraction at rest.
• C. Visualize coronary arteries directly using a catheter.
• D. Detect valvular regurgitation.

Answer: (A)

Myocardial perfusion imaging is used to evaluate how blood is delivered to different regions of the heart muscle. A radioactive tracer is taken up by viable myocardium in proportion to blood flow, and images are captured at rest and during stress to reveal regional perfusion. Areas with reduced tracer uptake during stress indicate under-perfusion from ischemia, while defects that are present at rest suggest infarction or scar. This information helps determine the presence and extent of coronary artery disease and guides treatment decisions, such as whether revascularization might help. Other assessments, like ejection fraction, direct visualization of arteries with catheter, or valvular function, rely on different tests and modalities.