muga

The Multigated Acquisition (MUGA) scan is a nuclear medicine test used to assess cardiac systolic function, with a primary focus on left ventricular ejection fraction (LVEF). It employs technetium-99m labeled red blood cells and electrocardiogram gating to acquire multiple images across the cardiac cycle, allowing quantitative measurements of chamber volumes and wall motion.

Technique summary: A small amount of the patient’s blood is labeled with Tc-99m and reinjected. A gamma camera, synchronized to the ECG, captures frames through the heartbeat. Planar MUGA scans are common, and single-photon emission computed tomography (SPECT) variants exist. The exam is typically performed at rest and lasts about 30 to 60 minutes. The result provides an objective LVEF and regional wall-motion assessment, with high reproducibility for serial comparisons.

Clinical use and interpretation: MUGA scans are widely used to monitor cardiac function in patients receiving potentially cardiotoxic chemotherapy (for example, anthracyclines) and to track changes in heart performance over time. They are also employed in certain cases of heart failure or after myocardial infarction when precise, repeatable quantification of EF is needed. Advantages include strong reproducibility and reduced dependence on operator skill, making it useful when echocardiographic windows are poor. Limitations include exposure to ionizing radiation and lack of detailed perfusion information, which means it cannot replace perfusion imaging or provide the full anatomic detail of MRI or CT in all scenarios.

Safety and alternatives: Radiation dose is a consideration, particularly for serial testing. MUGA is often balanced against echocardiography or cardiac MRI, which may offer real-time imaging or superior tissue characterization without ionizing radiation.