A MUGA scan (Multiple Gated Acquisition scan) is a type of nuclear medicine imaging study used to assess the pumping function of the heart. It measures the ejection fraction of both the left and right ventricles and evaluates regional wall motion (how different areas of the heart muscle contract). Unlike echocardiography, which uses ultrasound to produce structural images, a MUGA scan shows functional information about the heart’s performance as a pumping system.
During the procedure, a small amount of a radioactive tracer (typically technetium-99m, attached to the patient’s own red blood cells) is injected into a vein. A gamma camera detects the radiation emitted by the tracer as the heart beats, and the images are gated (synchronised) with the ECG to capture each phase of the cardiac cycle. By comparing the amount of radioactivity in the left ventricle at the start and end of systole, the ejection fraction can be calculated with high accuracy.
MUGA scanning was historically one of the most precise methods for measuring ejection fraction and remains useful when echocardiography gives technically limited images. It is also used to monitor cardiac function in patients receiving chemotherapy drugs (such as certain anthracyclines) that carry a risk of cardiotoxicity, where serial measurements are needed to detect early deterioration in ventricular function.
For cardiac arrest survivors with impaired left ventricular function, accurate ejection fraction measurement is important in decisions about ICD implantation. A MUGA scan may be requested when echocardiographic images are suboptimal or when a highly reproducible serial measurement is needed to track recovery of function over time.
« Back to Glossary Index