A MUGA scan — short for “multiple-gated acquisition” — is also known as radionuclide angiography or radionuclide ventriculography. It is a nuclear imaging test that’s typically performed to give doctors information about the efficiency of your heart when pumping blood. What do you need to know about it?
The purpose of a MUGA scan
Tests like echocardiograms and EKG are preferred in the initial phase of heart-related diagnoses because they are non-invasive and complication-free. But, sometimes, these tests can be inconclusive, in which case a MUGA scan might shed light on the situation and confirm the diagnosis. The MUGA scan can provide information on the amount of blood your heart pumps with each heartbeat. People suffering from heart disease may have difficulty in pumping the required amount of blood, which can lead to heart failure.
A MUGA scan involves injecting a radioactive substance (called a tracer) into your bloodstream. This substance attached to the red blood cells, while a gamma camera records images of your heart. At the other end of the camera is a computer that recreates these imagines, showing doctors how your heart’s chambers are pumping blood. The gamma camera is triggered by the electrical signals recorded in real-time by the EKG machine you’re connected to.
Generally speaking, the MUGA scan is a risk-free test. Even if it implies injecting a radioactive substance, it has very little impact on your body. However, pregnant and nursing mothers should avoid this type of scan (or any other type of nuclear test), because the radiation might prove harmful to the baby.
What to expect from a MUGA: Before the scan
A MUGA scan consists of two parts: taking the test while you’re resting, but also while you’re exercising. Because of the nature of the test, doctors will prepare you by giving you important information beforehand.
They will ask about any and every type of medication or supplements you might be taking and could ask you to stop taking the ones that could interfere with the test results. They will also tell you to avoid caffeine-based drinks and alcohol the day before the test, as this interferes with your heart’s normal rhythm.
MUGA: During the scan
You will pretty much know what to expect before the scan, as the doctor or the technician performing it will explain what happens every step of the way. Since the scan requires special equipment, it’s only done in hospitals or clinics that are authorized to perform this test and have the right tools for it.
Before the test, the doctor or technician will attach a series of disks to your body. These are called electrodes and are placed on your arms, legs, and on your chest. The electrodes are connected to an EKG machine via wires. The purpose of the machine is to record the electrical signals of your heart.
The tracer will be injected via an IV line. As you are subjected to the resting scan, you will lie on a table that has a camera above it. This is called a gamma camera and will take several pictures of your chest, from multiple angles. The camera will take pictures whenever your heart pumps blood, triggered by the recordings of the EKG machine.
When taking the exercise scan, you will be required to walk on top of a treadmill or ride a stationary bicycle. The test will gradually get more demanding, in order for the doctor to see what is the highest exercise rate that your heart can take without being at peril. During this entire time, the camera will take images of your heart.
Once the stress test is completed, you will have to lie down on a table for the remainder of the tests. Note that a MUGA scan can take between one and two hours, so clear your schedule.
After the scan
While your doctor knows how to analyze your test results, here are some things you might want to know about them:
- The results of the MUGA scan are in the form of percentages.
- If you have a percent that varies between 50 and 70, your heart is pumping blood normally.
- If your result is below 40 percent, you might have coronary artery disease, left ventricular systolic dysfunction, or be at a mild to severe risk of a heart attack.
- If your result is between 40 and 55 percent, you could suffer from chemotherapy damage, myocardial infarction, or heart muscle damage.
- If your result is over 75 percent, you have hypertrophic cardiomyopathy.
Abnormal results might also indicate other conditions, such as problems with the heart valves, artery blockage, desynchrony, or dysfunctions in the pumping mechanism of your heart.
MUGA scans are a good way of testing the efficiency of your heart when it comes to pumping blood. A chemical compound, which is a radioactive substance called a tracer, is injected into your bloodstream.
A gamma camera will receive a signal from the EKG machine you are connected to, knowing to take pictures when your heartbeats. The purpose of the test is to examine the amount of blood that leaves the heart with each beat. The result comes in percentage form and can warn your doctor about possible problems with your heart.