Which test involves the injection of a nuclear tracer to visualize heart function?

The multiple gated acquisition scan (MUGA) is a diagnostic imaging test that utilizes a nuclear tracer to assess the heart's function, specifically its pumping ability. In this procedure, a small amount of radioactive material is injected into the bloodstream, which allows for the visualization of the heart during the heartbeat cycle. This process provides precise information on the ejection fraction, which measures how well the heart is able to pump blood, and can help in diagnosing various heart conditions, including heart failure.

The use of a nuclear tracer distinguishes MUGA from other imaging techniques. For instance, magnetic resonance imaging (MRI) uses magnetic fields and radio waves to generate detailed images of the heart without needing a tracer. An electrocardiogram (ECG) is a test that measures the electrical activity of the heart and does not involve imaging, while a transesophageal echocardiogram uses ultrasound waves to create images of the heart from a different angle, typically through the esophagus, and also does not employ nuclear tracers. MUGA, thus, is unique in its use of nuclear imaging technology to evaluate cardiac function.