MUGA Scan: Meaning, Prep, Procedure, Risks, Score, and Results

When your doctor wants to see how well your heart is pumping, they have a lot of options:
echocardiogram, MRI, CT, alphabet soup. One of the most precise tools in that alphabet is the
MUGA scan, a type of nuclear medicine test that measures how efficiently your
heart’s ventricles squeeze blood out with every beat. It’s especially common if you’re getting
certain cancer treatments or you have suspected heart failure.

Despite the intimidating full namemultiple-gated acquisition scanthe experience is
usually pretty straightforward. You lie still under a special camera while a tiny amount of
radioactive tracer flows through your bloodstream, and the machine creates a kind of “movie” of
your heartbeat. From those images, your care team calculates your ejection fraction
(EF) and other measurements that guide treatment.

Let’s walk through what a MUGA scan is, how to prepare, what happens during the test, what the
“score” really means, and what to know about risks and resultswithout the medical-jargon
headache.

What Is a MUGA Scan?

A MUGA scan (multiple-gated acquisition scan) is a nuclear medicine imaging
test that tracks a small amount of radioactive tracer as it moves through your blood, allowing a
gamma camera to capture detailed images of your heart as it beats. It focuses on the lower
chambers of the heartthe right and, especially, the left ventricleand measures how much blood
they pump out with each contraction.

You might also hear it called:

• Equilibrium radionuclide angiogram (ERNA)
• Radionuclide ventriculography (RNV or RVG)
• Radionuclide angiography (RNA)
• Cardiac blood pool scan

All of these terms describe essentially the same idea: using a radiotracer and a gamma camera to
create a highly accurate picture of how well your heart pumps.

Why a MUGA Scan Is Ordered

Your provider might order a MUGA scan to:

• Check baseline heart function before starting certain chemotherapy drugs (such as
  anthracyclines or HER2-targeted therapies) that can weaken the heart muscle.

• Monitor your heart during and after cancer treatment to catch cardiotoxicity early.
• Evaluate suspected or known heart failure and follow how well treatment is working.
• Assess unexplained shortness of breath, fatigue, or reduced exercise capacity.
• Check heart function before certain major surgeries or transplant evaluations.

MUGA scans are particularly valued for their reproducible, precise measurement of
ejection fraction, which is why they were historically considered a gold standard for
chemo-related heart monitoring, even as high-quality echocardiography and cardiac MRI have
become more common.

How a MUGA Scan Works (Without the Physics Lecture)

The core idea is simple: tag your red blood cells with a small amount of radioactive material,
then take timed pictures as those cells move through the chambers of your heart. A computer
synchronizes those images with your ECG (heart rhythm tracing) so it can reconstruct one clean,
detailed heartbeat cycle, frame by frame.

Most MUGA scans follow these general steps:

1. IV placement: A technologist places an IV line in your arm. Through this IV,
   they may first inject a “tagging” agent (such as stannous compound) that helps the tracer bind
   to your red blood cells.
2. Radiotracer injection: A short time later, they inject a small amount of a
   radiotraceroften technetium-99m–labeled red blood cellsinto the IV.

3. Heart “movie” recording: You lie on a scanning table while a gamma camera is
   positioned close to your chest. The camera isn’t noisy or enclosed like an MRI; it simply
   hovers over you, usually in a few different positions around your chest.
4. ECG gating: Sticky patches (electrodes) are placed on your chest to track
   your heart rhythm. The machine uses that rhythm to “gate” the images, meaning it lines up each
   frame with a specific phase of your heartbeat.
5. Image processing: A computer combines those frames into a moving, averaged
   image of your heart through a full cardiac cycle. From that, the system calculates your left
   ventricular ejection fraction and sometimes right ventricular function as well.

The imaging part typically takes about 20–45 minutes, though the whole visit may last 1–2 hours
depending on how your nuclear medicine department is set up.

How to Prepare for a MUGA Scan

Good news: compared with many tests, MUGA scan preparation is usually very simple.
In many centers, you:

• Can eat and drink as usual.
• Take your regular medications unless your doctor tells you otherwise.
• Wear comfortable clothing and a top that’s easy to remove or move out of the way.

Many hospital instructions explicitly say there is no special preparation for a
standard resting MUGA scan.

Common Pre-Scan Instructions

• Clothing and jewelry: You’ll be asked to remove necklaces, body chains, and
  other metal items around your chest because they can interfere with the images.

• Pregnancy and breastfeeding: If you are pregnant, think you might be pregnant,
  or are breastfeeding, let your care team know. Nuclear medicine tests with radiation are
  usually avoided in pregnancy and may require special timing or pumping/holding breast milk if
  you’re nursing.
• Allergies and medications: Tell your team about any previous reactions to
  nuclear medicine tracers or contrast dyes, and bring an up-to-date medication list.
• Exercise MUGA: In some centers, a MUGA may be done with mild exercise (for
  example, on a bike or treadmill) to see how your heart functions under stress. If that’s
  planned, you may be asked to avoid heavy meals or caffeine beforehand.

If your instructions from the hospital or imaging center differ from anything you’ve read
online, their directions win. Always follow the written instructions from your own care team.

What to Expect During the Procedure

A typical MUGA scan experience looks like this:

1. Check-in and consent: You arrive at the nuclear medicine department, sign
   consent forms, and confirm allergies, medications, and pregnancy status.
2. IV and tagging: The technologist places an IV, injects the tagging agent, then
   later injects the radiotracer. You might feel a brief sting or warm sensation, but most people
   tolerate it well.
3. Electrodes and positioning: Stick-on ECG patches go on your chest to track
   your heartbeat. You’ll lie on your back (sometimes slightly turned) on the scanning table.
4. Imaging: The gamma camera moves into position close to your chest and takes
   pictures in several projections (for example, facing straight forward and from the side). You
   need to stay as still as possible, but you can breathe normally. The camera doesn’t touch you
   and is generally not claustrophobic.
5. After the scan: The IV is removed, you’re given any follow-up instructions,
   and you can usually go home or back to your normal day right away.

Many people describe a MUGA scan as “boring but easy”the main challenge is lying still and
resisting the urge to scratch your nose at the worst possible moment.

Risks and Side Effects of a MUGA Scan

Overall, a MUGA scan is considered a low-risk, noninvasive test. But it isn’t
completely risk-free.

Radiation Exposure

The main risk comes from the small amount of radiation used in the radiotracer. The dose varies
by protocol, but it’s generally within the range considered acceptable for diagnostic imaging
and is often lower than or comparable to many CT scans.

The tracer is designed to clear from your bodymostly through the kidneyswithin about
24 hours. Drinking plenty of fluids and urinating frequently helps flush it
out.

Other Possible Risks

• Injection-related issues: Mild pain, bruising, or swelling at the IV site is
  the most common minor side effect. Bleeding or infection at the site is rare.

• Allergic or sensitivity reactions: Serious allergic reactions to the
  radiotracer are very rare but possible. Your team will monitor you and has medication on hand
  if this occurs.
• Pregnancy and breastfeeding: Because any radiation exposure to a fetus or
  nursing infant is taken seriously, MUGA scans are usually avoided in pregnant people and used
  cautiously in those who are breastfeeding.
• Frequent repeat scans: When MUGA scans are repeated many timesfor example,
  during long cancer treatmentsdoctors weigh the benefits of close heart monitoring against the
  cumulative radiation exposure, often considering alternatives like echocardiography.

If you have concerns about radiation, it’s completely reasonable to ask, “What’s my estimated
dose from this test, and are there non-radiation alternatives in my case?”

MUGA Scan Score: Understanding Ejection Fraction

The “score” most people care about after a MUGA scan is the ejection fraction (EF).
This is the percentage of blood pumped out of the left ventricle (the main pumping chamber)
every time it contracts.

While “normal” can vary slightly by lab, common reference ranges look roughly like this:

• Normal EF: about 50–70%
• Borderline or mildly reduced EF: about 41–49%
• Reduced EF: 40% or lower

Your report may mention left ventricular ejection fraction (LVEF), and in some
cases right ventricular EF as well. Because MUGA scans are highly reproducible, small drops in
EF (for example, from 60% to 50%) may be a stronger signal of concern than a one-time reading
alone, especially during chemotherapy monitoring.

How Doctors Use the Score

Depending on why you had the test, your care team may use the MUGA scan results to:

• Decide whether it’s safe to start or continue certain chemotherapy drugs that can affect the
  heart.
• Adjust heart failure medications, such as ACE inhibitors, beta-blockers, or diuretics.
• Plan follow-up tests or imaging to clarify borderline results or unexpected changes.
• Evaluate your risk before major surgery or other intensive treatments.

One important note: a MUGA scan is great at measuring EF, but it doesn’t show
as much detail about heart valves, muscle thickness, or structural abnormalities as an
echocardiogram or cardiac MRI. That’s why MUGA is usually just one piece of the bigger picture.

How MUGA Compares With Other Heart Tests

If you’ve already had an echocardiogram, you might wonder why anyone would add a MUGA scan to
the mix. Each test has strengths:

• MUGA scan – Very precise, reproducible EF measurement; particularly useful
  for serial monitoring in oncology. Involves radiation and limited structural detail.

• Echocardiogram – Widely available, no radiation, excellent for valve and
  structural assessment; EF can vary more depending on image quality and reader experience.

• Cardiac MRI – Very detailed anatomy and function, highly accurate EF, but
  less available, more time-consuming, and not suitable for everyone (for example, certain
  implanted devices).

Increasingly, cardiology and oncology teams use a multimodality approachfor
example, starting with MUGA and then using high-quality echocardiography for follow-up, or
turning to MRI for complex cases.

After the MUGA Scan: Results and Next Steps

You probably won’t get your “score” the moment you hop off the table. A nuclear medicine
physician or cardiologist reviews the images, checks the EF and other measurements, and sends a
formal report to your ordering provider.

When you review your results, consider asking:

• What is my ejection fraction, and how does it compare with normal?
• Has my EF changed compared with previous tests?
• What do these results mean for my current or planned treatment?
• Will I need repeat scans or other types of heart imaging?

Try not to fixate on a single number out of context. Your EF is important, but so are your
symptoms, other imaging findings, blood pressure, heart rhythm, and overall health.

Real-World Experiences: What Patients Often Notice

Reading about a MUGA scan on paper is one thing; living through it is another. While
everyone’s experience is unique, many people report a similar pattern.

Before the Scan: Anxiety and “What Ifs”

For people going through cancer treatment, a MUGA scan can feel emotionally loaded. It’s not
just a test; it’s a progress report on how well your heart is tolerating powerful medications.
There’s a very human fear behind the question: “What if my heart can’t handle this?”

Common worries include:

• Fear of radiation exposure.
• Concern about potential bad news from the results.
• General uneasiness with medical procedures and IVs.

Many people say that after they’ve done one MUGA scan, the fear of the unknown shrinks
dramatically. The test itself tends to be less dramatic than their imagination.

During the Scan: Mostly Boredom, Minimal Drama

Once you’re on the table, most of the experience is waiting. You’ll feel the IV placement and
injections, but these are typically brief. The camera hovers over your chest without squeezing
or enclosing you, which is helpful if you’re claustrophobic.

The trickiest part is staying still. People often describe their internal monologue as:
“Don’t move. Don’t cough. Definitely don’t sneeze.” Chatting with the technologist before the
scan, asking how long each set of images lasts, and focusing on your breathing can make the time
pass more comfortably.

If you have joint pain, back problems, or trouble lying flat, it’s worth telling the team before
the scan starts. They can often adjust the table, add pillows under your knees, or take short
breaks between image sets.

After the Scan: Waiting on Results

Physically, most people feel back to normal right away. You might be told to drink extra water
to flush out the tracer. There are usually no activity restrictions, so many patients head
straight back to work, home, or the infusion center.

Emotionally, the waiting can be harder than the scan. This is especially true if the test is
being used to decide whether a beloved cancer treatment can continue. Some patients describe
feeling like they’re “waiting for a report card” on their heart.

When the results arrive, it can help to have someone with you (in person or by phone) during the
appointment. If the EF is normal or stable, that can be a huge relief. If it has dropped, the
conversation may shift to balancing heart protection with cancer controlsomething cardio-oncology
teams are increasingly skilled at navigating.

Practical Tips from Patient Experience

• Dress in layers: Nuclear medicine departments can be chilly. A zip-up hoodie
  or cardigan that’s easy to remove around the chest area is ideal.
• Ask about timing: Knowing how long the entire visit will take can help you
  plan snacks, rides, and work or caregiving commitments.
• Hydrate afterward: Unless your doctor has restricted fluids, drinking water
  post-scan helps clear the tracer and can be a simple “I’m taking care of myself” ritual.
• Write down questions: It’s easy to forget what you wanted to ask once you’re
  sitting in the exam room. Jot questions in your phone notes ahead of time.
• Remember the goal: The purpose of a MUGA scan isn’t to “catch you failing”; it
  is to protect your heart while you’re dealing with bigger health issues. Shifting the frame
  from judgment to safety can make the process feel more collaborative and less frightening.

At its best, a MUGA scan offers an early warning system. If your heart is showing signs of
strain, your team can modify treatment, add heart-protective medications, or choose different
options. If your EF is holding steady, it’s one more piece of reassuring information that the
plan is working for both your cancer (or heart condition) and the rest of you.

Bottom line: a MUGA scan is a detailed check-in on one of your most important organs. It may not
be anyone’s favorite afternoon activity, but it’s an important tool for keeping your heartand
your treatmenton the safest possible path.