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Nuclear Medicine / Imaging

Dr. Alrich L. Gray // Central Montana Heart & Vascular Institute

Nuclear Medicine / MUGA scans

A multigated acquisition scan (also called equilibrium radionuclide angiogram or blood pool scan) is a noninvasive diagnostic test used to evaluate the pumping function of the ventricles (lower chambers of the heart). During the test, a small amount of radioactive tracer is injected into a vein. A special camera, called a gamma camera, detects the radiation released by the tracer to produce computer-generated movie images of the beating heart. The MUGA scan is a highly accurate test used to determine the heart’s pumping function.

During the test you can expect the following:

  • A technician will attach electrodes (small, round adhesive patches) to the skin of your chest. Men may have their chest hair shaved to allow a better connection. The electrodes are attached to an electrocardiograph monitor (EKG) that charts your heart’s electrical activity during the test.
  • An intravenous (IV) line will be inserted into a vein in your arm.
  • The technician will ask you to lie on the exam table under the gamma camera. A nuclear imaging technician will draw a small amount of blood, combine it with a radioactive tracer, and inject the mixture into your IV. The radioactive tracer tags your red blood cells, so they can be detected by the camera. The tracer stays in your bloodstream for several hours and does not enter your tissue cells.
  • The camera above the table is focused on the heart and analyzes the amount of radiolabeled red blood cells pumped from the heart with each heartbeat. Several images can be taken to look at the different walls of your heart.
  • This test calculates your ejection fraction, a measurement of how well your heart pumps with each beat. A normal ejection fraction ranges from 50-70 percent. An ejection fraction of 65 percent, for example, means that 65 percent of the total amount of blood in the left ventricle is pumped out with each heartbeat. The ejection fraction may be lower when the heart muscle has become damaged due to a heart attack, heart muscle disease (cardiomyopathy), or other causes.