MUGA Scan

A multigated acquisition (MUGA) scan is an imaging test that may help determine how well the heart is functioning. It generates internal images of the heart and checks whether blood is being properly pumped through its lower chambers.

The imaging test has two main elements:

• A special scanner (large camera) to take the pictures
• A “tracer,” which acts as a dye in the blood to highlight some of the blood cells

Before the procedure, the tracer, which is a small amount of radioactive material, is injected into a vein through an intravenous (IV) line. The tracer follows red blood cells and reveals how blood travels through the heart while the scanner takes pictures.

MUGA scan vs. echo

A MUGA scan and an echocardiogram (echo) both generate images showing how the heart beats. There are key differences in what each exam evaluates:

• Using sound waves, an echo allows the care team to see exactly how the patient's heart pumps blood.
• Using nuclear imaging via a radiotracer, a MUGA scan provides the care team with a precise reading of the patient's ejection fraction (EF), which measures how much blood is pumped out of the heart.

What is a MUGA scan used for?

Certain types of chemotherapy drugs or other cancer drugs may damage the heart. Before, during or after treatment with these drugs, a MUGA scan may be used to check on the heart and make sure it’s operating normally. If a MUGA scan reveals any abnormalities that may be due to treatment, the doctor may recommend a different drug.

Cancer treatments may lead to long-term side effects. MUGA scans may also be used to check for heart problems in patients with certain past cancer treatments, such as:

• Radiation therapy in the chest area
• Some types of chemotherapy drugs
• Bone marrow and stem cell transplants

What to expect during a MUGA scan

A MUGA scan is an outpatient procedure, which means most people go home the same day as the procedure. To undergo a MUGA scan, the patient will likely visit a hospital or an outpatient imaging facility.

The scan is performed by a nuclear medicine technologist and evaluated afterward by a cardiologist or radiologist.

The patient's doctor may provide specific instructions before the test. In general:

• The patient may be told not to eat or drink within four to six hours of the test and to cut out caffeine and tobacco for 24 hours leading up to it.
• Check with the doctor regarding any concerns or questions about the instructions or getting the scan. Feel free to ask about the risks and benefits of any test, the cost, and what the next steps may be based on the results.

Once the patient arrives at the facility and is ready for a MUGA scan, the person performing the scan places electrodes on his or her chest. The electrodes are small, plastic patches that stick to the skin and measure the heart rate throughout the scan.

An IV line is inserted into a vein to inject the tracer. Once IV access is established, the remainder of the procedure should cause no discomfort.

Next, the patient may be asked to lie down while the scanner is positioned over his or her chest. The scanner takes pictures from various angles, tracking how the tracer moves through the heart. Each image takes about five minutes to complete. Between pictures, the patient may need to move around and get his or her heart rate up to show how well the heart functions under stress.

In total, a MUGA scan may take up to three hours to complete.

Understanding MUGA scan results

The care team typically contacts the patient when the results from the scan are ready. The results will include the ejection fraction:

• An EF between 50 percent and 75 percent is considered in the normal range.
• An EF result of less than 50 percent or above 75 percent may indicate a heart problem, but the doctor will indicate whether it's something to be concerned about.

Patients who are currently being treated with chemotherapy or another cancer drug that may be causing the problem may be advised to adjust their treatment plans.

MUGA scan side effects and radiation exposure

The radiotracer that technologists use during MUGA scans isn’t harmful to the patient, and typically only stays in the body for 24 hours. However, a risk of radiation exposure is likely, particularly in people of specific demographics. 

For instance, patients who are pregnant or breastfeeding should talk to their care teams about whether a MUGA scan is safe for them.