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MUGA scan

What is a MUGA Scan?

A MUGA (Multi-Gated Acquisition) scan is a specialized test that provides detailed information about how well your heart muscle is pumping. This test creates precise measurements of your heart’s pumping efficiency by tracking the movement of your own blood cells through your heart chambers.

Why Might I Need a MUGA Scan?

Your doctor may recommend a MUGA scan to:

  • Determine how well your heart is pumping blood (your ejection fraction)
  • Evaluate heart function before, during, or after chemotherapy treatments, as some cancer medications can affect the heart
  • Assess damage after a heart attack
  • Monitor heart function in heart failure
  • Evaluate heart valve function
  • Check heart function before and after heart surgery
  • Follow up on abnormal findings from other cardiac tests

How Does a MUGA Scan Work?

The test works by:

  1. Labelling your red blood cells with a radioactive substance (this process is called “tagging”)
  2. Alternatively, a small amount of your blood is drawn and mixed with a substance that makes your red blood cells slightly radioactive. These tagged blood cells are then injected back into your bloodstream
  3. As the tagged red blood cells flow through your heart, they emit tiny amounts of radiation (gamma rays)
  4. A special camera detects these gamma rays and creates images of your heart as it beats
  5. The computer synchronizes these images with your ECG (electrocardiogram) to show your heart throughout its pumping cycle
  6. This allows precise calculation of your ejection fraction (the percentage of blood pumped out with each heartbeat)

Preparing for Your MUGA Scan

  • No special dietary restrictions are typically required
  • Continue taking your regular medications unless instructed otherwise
  • Wear comfortable clothing without metal buttons or zippers at chest level
  • You may be asked to avoid caffeine for 24 hours before the test
  • Important: Inform your doctor if you:
    • Are or might be pregnant
    • Are breastfeeding
    • Have an irregular heartbeat (arrhythmia)
    • Have had allergic reactions to medical procedures in the past
    • Have difficulty lying flat for extended periods

What to Expect During the Procedure

Before the Scan

  1. You’ll be asked to complete a brief questionnaire about your medical history
  2. A healthcare professional will check your vital signs and explain the procedure
  3. An IV line will be placed in your arm for blood drawing and later injection

Blood Labeling Process

  1. A small amount of radioactive substance will be added to your blood that will label your red-blood cells
  2. Alternatively, a small amount of your blood (about 3-5 teaspoons) will be drawn
  3. This blood will be mixed with the radioactive substance in a special lab
  4. This process takes approximately 20-30 minutes

During the Scan

  1. ECG leads (small adhesive patches) will be placed on your chest to monitor your heart rhythm
  2. Your tagged red blood cells will be injected back into your bloodstream through the IV
  3. You’ll lie on an examination table under a gamma camera
  4. You’ll need to lie still during the imaging, which typically lasts about 10-15 minutes
  5. The camera will take multiple images of your heart as it beats
  6. You may be asked to change positions for additional views
  7. The camera does not produce radiation – it only detects the minimal radiation from your tagged blood cells

Potential Discomfort

  • The test itself is painless
  • You may experience minor discomfort from:
    • The needle insertion for blood drawing and IV placement
    • Lying still on the examination table
    • The table may be hard and slightly cold

After Your MUGA Scan

  • You can resume all normal activities immediately
  • There are no restrictions on eating or drinking after the test
  • The radioactive substance loses its radioactivity quickly and is eliminated from your body naturally within 24 hours
  • A cardiologist or nuclear medicine specialist will analyze your scan
  • Your doctor will discuss the results with you at your next appointment

What Do the Results Mean?

  • The main measurement from a MUGA scan is the ejection fraction
  • A normal ejection fraction is typically between 50% and 70%
  • Lower values may indicate that your heart is not pumping as efficiently as it should
  • Your doctor will interpret these results in the context of your specific medical situation

Are There Any Risks?

The MUGA scan involves exposure to a very small amount of radiation. The benefits of the information gained from the scan far outweigh any potential risks from this minimal radiation exposure. The amount of radiation received during a MUGA scan is comparable to what you would receive from natural background radiation over a few months.

How Long Will the Entire Procedure Take?

The entire procedure typically takes about 1½ hours:

  • 30 minutes for blood drawing and tagging
  • 15 minutes for setup with ECG leads
  • 15-20 minutes for the actual scanning
  • Additional time for preparation and possible extra views

If you have any questions or concerns about your MUGA scan, please discuss them with your healthcare provider.

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