A radionuclide angiogram is a test used to gather images of the heart throughout its pumping cycle. You may also hear it referred to as a MUGA scan (multigated acquisition scan) or blood pool scan. The test can help assess how well your heart is pumping by measuring what is called the “ejection fraction,” the amount of blood that is pumped out of the heart’s two lower chambers (the ventricles). Generally, a healthy ejection fraction range is 50 to 70 percent. The test can be used to determine damage from a heart attack or chemotherapy, for example. A radionuclide angiogram may be performed at rest, or you may be asked to exercise to “stress” the heart.
How Does It Work?
For a radionuclide angiogram, a small amount of a radioactive tracer (technetium-99m) that emits gamma rays is injected into the bloodstream. The tracer “tags” red blood cells, making it possible to gather images of blood circulation in the heart. The gamma rays emitted by the tracer in the bloodstream are detected by a gamma camera. After the gamma rays are converted into an electrical signal, they go to a computer, which creates an image of the chambers of the heart.
How Is It Performed?
The technician who is performing the test will attach electrodes to your chest for electrocardiography (ECG, EKG) that will also take place during the scan. You will be asked to lie down on an exam table under a gamma camera. A small amount of your blood will be drawn and mixed with the radioactive tracer, which will then be injected back into your bloodstream.
If your MUGA scan will be used to assess how well your heart functions when you are exercising, you may be asked to lie on an exam table that has pedals at the end. You will be asked to pedal with your feet while the images are being gathered. Or you may be asked to exercise on a treadmill or stationary bike.
Is it Safe?
The radioactive chemicals used in typical doses for a radionuclide angiogram are considered safe. The chemicals leave the body quickly in the urine. However, as with x-rays and other types of radiation, gamma rays may affect an unborn child. Let your doctor know if you are pregnant or may be pregnant.
Questions to Ask Your Doctor About Radionuclide Angiogram/MUGA Scans
The following questions can help you talk to your physician about having a radionuclide angiogram/MUGA scan. Consider printing out or writing down these questions and taking them with you to your appointment. Taking notes can help you remember your physician’s response when you get home.
- What symptoms or test results indicated that a radionuclide angiogram/MUGA scan might be beneficial?
- What information can a MUGA scan give us about my heart health?
- Will my MUGA scan be an “exercise” test or a “resting” test?
- Do I need to have an empty stomach before the procedure? Should I withhold any of my medications? Are there any medications that I will need to take?
- How much radiation will I be exposed to during the test?
- What happens next if the scan shows that my heart is not pumping as much blood out of the lower chambers as it should?
Please print this list of questions here. Take them with you to the doctor and share them with friends and loved ones when you are encouraging them to see their doctors.