What is a MUGA scan?
Red blood cells tagged with a radioactive substance remain intravascular as normal red cells do. These, however, emit gamma rays and can be imaged using a particular machine called a gamma camera.
We break up the cardiac cycle into small segments using the intervals on an ECG as a guideline. As each cycle repeats with each heartbeat, corresponding gamma-ray counts are placed in the same parts over time even though they are different beats. When reconstructed on the processing computer, this gives us an image that shows the heart beating and, more specifically, how the heart chambers’ blood volumes change during one heartbeat. This data can also be represented on a plot and used for various functional cardiac parameters.
This allows us to determine the amount of blood ejected by the heart in each heartbeat (called the ejection fraction). Other measurements are also possible.
In modern nuclear medicine, the ejection fraction is significant in chemotherapy patients since many of these drugs are cardiotoxic, i.e. damaging the heart muscle. By monitoring the ejection fraction, we can determine when it is advisable to stop treatment to preserve heart function.
What can I expect to happen next?
Please inform your radiographer if you have an irregular heartbeat before drawing blood. This will spare you a lot of discomfort and not waste your time. This imaging can only be performed if your heart rate is reasonably regular.
A small amount of blood will be drawn and labelled to be radioactive. This can take a while.
ECG leads will be placed on you to record your heartbeat.
You will be imaged at injection (on the imaging bed) for at least 500 heartbeats or 10 minutes – whatever comes first.
How long will the whole scan take?
Approximately up to 1 ½ hours (including labelling the red blood cells)
