A MUGA scan is a nuclear medicine heart scan used to measure how well your heart pumps blood. One of its main jobs is to calculate the ejection fraction, which is the percentage of blood your heart pumps out with each beat.
This scan is especially useful when doctors want a closely measured assessment of heart pumping function, including in some patients receiving cancer treatment that could affect the heart.
What does MUGA stand for?
MUGA stands for multigated acquisition scan.
You may also hear other names, such as radionuclide ventriculography. In practical terms, it is a nuclear medicine test that measures heart pumping performance.
Why might my doctor request a MUGA scan?
Your doctor may request a MUGA scan to:
- Measure your heart’s ejection fraction
- Assess symptoms that may suggest reduced heart pumping function
- Monitor heart function before, during, or after certain cancer treatments
- Compare heart performance over time
It is often used when the clinical question is specifically about how effectively the heart is pumping.
What does the scan show?
A MUGA scan mainly shows how the ventricles, especially the left ventricle, pump blood.
It can help assess:
- Ejection fraction
- How strongly the heart contracts
- Whether the pumping pattern looks abnormal
This gives doctors functional information rather than just a structural picture.
How is the tracer given?
A small amount of radioactive tracer is given by injection into a vein. The tracer is used so a special camera can follow blood movement through the heart.
In general, the imaging is timed with your heartbeat so the system can analyze how the heart contracts and relaxes over repeated cycles.
What happens during the test?
Although details vary, the general process includes:
- Electrodes being placed on your chest to track your heartbeat
- A tracer being injected into a vein
- You lying still while a gamma camera takes images of your heart
Some MUGA studies are done at rest. In some settings, an exercise version may also be used, but many patients will simply have a resting scan.
Will the scan hurt?
The scan itself is painless. You may feel a brief sting from the injection and mild discomfort from having to lie still, but most patients tolerate the study well.
Do I need to prepare before a MUGA scan?
Preparation depends on whether the scan is being done at rest or with exercise and on your local protocol.
Your center may ask you to:
- Avoid caffeine or tobacco beforehand
- Follow instructions about food and drink
- Wear comfortable clothing if exercise is involved
- Bring a list of your medicines
- Mention pregnancy or breastfeeding before the tracer is given
Because local instructions vary, always follow the guidance from your imaging center.
Can I eat or drink before the scan?
That depends on the specific protocol. Some studies allow a more normal routine, while others place limits on food, drink, caffeine, or exercise before the test.
How long does a MUGA scan take?
Many MUGA scans are completed within about one to two hours, though the total time depends on the protocol used and whether extra steps are needed.
Is a MUGA scan safe?
For most people, yes. The tracer amount is small and chosen specifically for diagnostic imaging.
Like other nuclear medicine studies, it does involve some radiation exposure, so the scan is used when the expected benefit of the information outweighs that exposure.
What about pregnancy or breastfeeding?
Tell the imaging team before the scan if you are pregnant, think you may be pregnant, or are breastfeeding.
Because this is a nuclear medicine study, those situations may affect whether the test should proceed and what advice you receive afterward.
Can children have a MUGA scan?
Yes, but this is a more specialized use case in children. If needed, dosing and planning are adjusted carefully, and the decision to perform the scan depends on the clinical question and the available alternatives.
When will I get my results?
A radiologist or nuclear medicine physician reviews the images and calculates the relevant measurements, including ejection fraction. The report goes to the doctor who requested the scan, and your doctor will explain what the findings mean for your care.
What are the important limitations and safety checks?
Nuclear medicine shows physiology and tracer uptake, but uptake is not always specific to one disease and spatial detail may be lower than CT or MRI. Inflammation, infection, treatment effects, medicines, blood glucose, recent imaging, movement, and the timing of images can change a result. A normal scan does not exclude every abnormality, and an abnormal focus may need correlation with CT, MRI, ultrasound, laboratory tests, biopsy, or follow-up imaging.
Preparation and radiation precautions are radiopharmaceutical- and protocol-specific. Tell the department before the tracer is given if you are or may be pregnant, are breastfeeding, care for a young child, or recently had another nuclear-medicine test. Do not stop medicines, fast, interrupt breastfeeding, or follow a fixed distancing period based only on a general webpage; obtain written instructions for the exact tracer, activity, and examination from the nuclear-medicine team.
Questions to ask your nuclear-medicine team
- Which radiopharmaceutical and protocol will be used, and what clinical question should the study answer?
- What exact fasting, hydration, medicine, diabetes, pregnancy, or breastfeeding instructions apply to me?
- Will CT be included, will contrast be used, and how does that change preparation and radiation exposure?
- What written precautions apply afterward, when will the signed report be ready, and who will explain any next step?
Sources and further reading
- RadiologyInfo.org: General nuclear medicine
- RadiologyInfo.org: Preparing for a nuclear-medicine examination
- IAEA: Basics of quality management for nuclear medicine practices
Conclusion
A MUGA scan is a focused nuclear medicine test used to measure how well the heart pumps blood. It is especially valuable when doctors need a reliable assessment of ejection fraction, particularly in patients whose treatment or symptoms make precise heart function monitoring important.