What Is a MUGA Scan?

Medically Reviewed by James Beckerman, MD, FACC on May 15, 2023
Written by WebMD Editorial Contributors
4 min read

‌A multiple-gated acquisition (MUGA) scan is a nuclear medicine test that shows how much blood your heart pumps with each heartbeat. An “exercise” or “stress” MUGA scan helps the doctor see how your heart handles hard work. A “resting” MUGA scan shows how well your heart pumps blood when you're lying still.

The doctor tags your red blood cells by injecting a radioactive liquid called a tracer or radionuclide. This tracer makes the blood cells show up on a special camera called a gamma camera. As the tagged blood cells make their way through your heart, the gamma camera takes pictures at certain times during each heartbeat.

The gamma camera can take pictures of the insides of the chambers of the heart because it picks up the radiation from the tracer. The blood that was tagged with the tracer looks bright, and the walls of your heart look dark in contrast. A computer strings these pictures together to make a kind of “movie” of the heart at work. 

You'll have another test, called an electrocardiogram (EKG or ECG) while the gamma camera takes its pictures. An EKG records the electrical activity in your heart. A heart doctor specially trained in nuclear testing (a nuclear cardiologist) matches the “movie” from the gamma camera with the heartbeat pattern from the EKG.

‌From the MUGA scan, the heart doctor can see whether your heart walls are moving normally. The heart doctor can also measure your ejection fraction (EF). Your ejection fraction is the percentage of the blood in the lower chambers of your heart that the heart is pumping out to your body with each heartbeat.  

A normal EF is between 50% and 70%. If your EF is low or heart walls are not moving as they should, your doctor will check you for these conditions:

  • ‌‌ Clogged arteries (blood vessels) that have kept your heart from getting the blood it needs
  • A chamber of the heart that's larger than it should be
  • A weak area (an aneurysm) of the heart muscle 
  • Damage to the heart as a side effect of medicines or other treatments

‌Before you schedule your MUGA scan, let your doctor know if you have a pacemaker or if you're pregnant or breastfeeding. Too much radiation during pregnancy can cause birth defects, and the tracer can make its way into breast milk. Your doctor will want to talk with you about your options.

Bring a list of all over-the-counter medicines, prescription medicines, and supplements (vitamins or herbs) you're taking. Make sure the tech or doctor doing the MUGA scan knows if you're allergic to any medicines, contrast dye, or iodine.‌

Wear comfortable shoes if you're having an exercise MUGA scan. Choose loose-fitting clothes that are easy to remove, no matter what type of scan you're having. You may need to wear a hospital gown during the test. Take out any piercings and leave all jewelry at home.‌

Your doctor will tell you if you need to skip meds or other pills or not eat before your test. If you're having a resting scan, you may need to stay away from alcohol and caffeine (coffee, tea, and soda) the day of the test. For an exercise MUGA scan, you won't be able to eat or drink anything except water for several hours before your test.

For the resting MUGA scan, a nurse, tech, or doctor will:

  1. place an IV (intravenous) line in your hand or your arm by inserting a thin needle into the vein
  2. put EKG leads (small round stickers) on your chest
  3. wrap a blood pressure cuff around your arm 
  4. inject the radioactive tracer into the IV line
  5. move the gamma camera into position over your chest
  6. ask you to lie quiet and as still as possible

‌During an exercise MUGA scan, you'll need to:

  1. ‌‌exercise on a treadmill or stationary bike until you reach your target heart rate or are too tired to continue
  2. let your nurse, tech, or doctor know if you have any pain or if you feel dizzy, short of breath, or extremely tired
  3. lie flat on a table afterward while the gamma camera takes another set of pictures

After your MUGA scan, a nurse or tech will take out the IV line, and you can go home. Just in case you feel a bit dizzy from lying flat during the test, move slowly when you get up off the table. Drink lots of fluids for the next couple of days to help flush the tracer out of your body. 

You can go right back to your normal activities as soon as the test is over.