Radionuclide Ventriculography or Radionuclide Angiography (MUGA Scan)

What is a MUGA scan?

Radionuclide ventriculography (RVG, RNV) or radionuclide angiography (RNA) is often referred to as a MUGA (multiple-gated acquisition) scan. It is a type of nuclear imaging test. This scan shows how well your heart is pumping.

Quick facts

• A MUGA scan is a test using a radioactive tracer (called a radionuclide) and a special camera to take pictures of your heart as it pumps blood.
• The test measures how well your heart pumps with every heartbeat.
• The test is called “multi-gated” because a gamma camera takes pictures at specific times during each heartbeat.
• The test may be done while you stay still (resting scan), exercise or both.
• The test measures your ejection fraction, which is the amount of blood pumped out of the heart during each heartbeat (contraction). It’s usually expressed as a percentage. For example, an ejection fraction of 60 percent means that 60 percent of the total amount of blood in the left ventricle when it is full is pumped out with each heartbeat. A normal ejection fraction is between 50 and 75 percent.

Why do people have a MUGA scan?

Your doctor may want to check how well your heart pumps blood. A MUGA scan helps your doctor learn more about why you may be having:

• Chest pain (angina)
• Trouble breathing
• Dizziness
• Tiredness

Your doctor may use this scan if other tests (like ECG or EKG) showed you may have a heart problem. It will show your doctor how much blood the heart pumps with each beat. Your heart may not be pumping enough blood to meet your body’s needs. This is called heart failure.

“My doctor told me that the MUGA scan showed my heart was actually pumping better than he thought. But he said one artery might be the cause of all my chest discomfort. So he scheduled me for an angiogram that will check that out.”  Jocelyn, age 58.

During the MUGA scan, a small amount of a radioactive substance or tracer (called a radionuclide) is put into your blood. The tracer attaches to your red blood cells. A gamma camera takes pictures of your heart. This lets doctors see the blood inside your heart’s pumping chambers (ventricles). The pictures are taken at the same time during each heartbeat (ECG-gated). A computer analyzes the pictures. The pictures show if areas of your heart muscle aren’t contracting normally and show how well your heart pumps blood. These tests are often done while you’re resting and exercising. A stress (exercise) test gives your doctor a better idea of how well your heart handles work. It helps your doctor decide the kind and level of exercise right for you.

What are the risks of a MUGA scan?

The radioactive substance you receive is safe for most people. Your body will get rid of it through your kidneys within about 24 hours. If you’re pregnant or think you might be pregnant, or if you’re a nursing mother, don’t have this test. It could harm your baby.

How do I get ready for my test?

• For a “resting” scan, your doctor may ask you to avoid drinks containing alcohol or caffeine such as coffee, tea or soft drinks for several hours before the test.
• For an “exercise” scan, don’t eat or drink anything except water for 4 hours before your test. Wear comfortable, loose-fitting clothing and comfortable shoes. 
• Your doctor will explain any changes in your medicine that you may need to make to prepare for the scan.

What happens during my MUGA scan?

• Specially trained technicians usually perform the scan in hospitals or clinics.
• During the scan, the technician places small metal disks (electrodes) on your chest, arms and legs. The disks have wires that hook to an electrocardiograph machine to record your ECG. The ECG tracks your heartbeat during the test. 
• An intravenous line (IV) is put into a vein in your arm. Doctors give the radionuclide through the IV line. For a “resting” scan, you will lie on a table with a special camera above it. The camera will take many pictures of your heart while you’re resting. 
• For an “exercise” scan, will generally walk on a treadmill or ride a stationary bicycle until you reach your peak activity level. Then, you’ll stop and again lie on a table while the gamma camera takes pictures of your heart. In some labs you may lie on a table and pedal a specially mounted bicycle. As you pedal, the camera will take pictures of your heart. 
• The tests take between 1 and 2 hours.

“I had never ridden a bicycle lying down, but it wasn’t too hard. This large camera was over my chest taking pictures while I was moving the pedals.”  Chris, age 63.

What happens after a MUGA scan?

• You can usually go back to your normal activities right away.
• Drink plenty of water to flush the radioactive material from your body.
• Your doctor who sent you for the test will get a written report of the test results. Make an appointment to discuss the results and next steps.

How can I learn more about MUGA scans?

Talk with your doctor.  Here are some good questions to ask:

• Why are you doing this test rather than a different one?
• What do I need to do to get ready for this test?
• When will I get the results of my test?
• Will I need to have more tests after this?
• Will you get enough information if I can’t exercise very long?