29 April 2018
Multi-gated radionuclide angiography (MUGA)
This is a test used to evaluate the cardiac muscle’s contraction and to measure its capacity to pump blood.
This information may be required by your doctor in different situations like, for example, after a heart attack, before and after certain chemotherapy treatments or if you have short breath.
An appointment needs to made for this test.
No preparation is needed. You do not need to fast nor cease your medication.
If you are pregnant or believe you may be or if you breastfeed, you must tell the medical staff before the exam.
No side effects
The marker does not have any side effect.
Even if it is lightly radioactive for a few hours, it is safe for you and for those around you. It will be eliminated from your body in the following hours.
Please tell us if:
If you are pregnant or believe you are, or if you are breastfeeding, you must tell the staff upon your arrival.
Two parts to the test
The test has two parts to it: first, a blood sample must be marked and second, the pictures are taken.
How it works
Upon your arrival, the technical staff will take charge of you.
A small, plastic catheter is installed in a vein in your arm, usually in the bend of the elbow.
This will be the only puncture necessary for the whole exam.
One hour maximum
The exam lasts approximately one hour.
What is the marking of the blood?
We then proceed with injecting a small dose of a medication through the catheter that will prepare the red blood cells to receive the radioactive marker.
This medication does not have any side effects. We let it act for 15 to 20 minutes.
Once the time has passed, we once again use the small catheter to pull out a small quantity of blood with a syringe.
This syringe contains a lightly radioactive liquid marker.
A short pause while the blood is "marked"
A 15-minute waiting period is then necessary for the red blood cells to be marked.
The liquid marker “attaches” itself to the red blood cells from the blood that has been previously removed and will allow for images to be taken of the movement of the blood in the heart.
This way, we can calculate the effectiveness of the cardiac pump.
Then, the blood is injected back into the veins.
Once the red blood cells from the sample are marked, the blood is injected back into the veins through the catheter.
The catheter is then removed.
Preparation for the pictures
Now that the blood is marked, we will ask you to remove your upper body clothing and to wear a hospital gown.
Images are taken using a special camera (gamma) in an on-the-back laying position with the arms lifted above the head.
The technologist will firstly place three small, electric captors (electrodes) on the thorax skin like those used during an electrocardiogram.
This will allow the camera to synchronise the images it will take with your heartbeat.
A first series of pictures
A first series of pictures is obtained during approximately ten minutes. The device will produce an image of a heart beat representing the average of hundreds of your heartbeats.
It is with this image that the nuclear medicine specialist will calculate the capacity for your heart to pump.
A second sequence
A second series of images taken over a 15-minute span is also taken while the camera detectors turn around you. There isn’t any danger of contact because these devices are equipped with anti-collision security systems.
This second part will allow for the creation of a 3D image of your heart and evaluation of its capacity to contract per region.
It is then over
Once these steps are done, the technologist will remove the electrodes from the thorax and you will return to put your clothes. You may then leave and continue your normal activities.
You may ask for a copy for another doctor
You may ask for a copy of your results to be sent to another doctor. You simply have to give the name and contact information of the doctor to the staff.
You may do so either before or after your exam.
If you leave the country on the same day...
However, if you plan on going through customs on that day or the following day, it is possible that security at customs detects the radioactivity in you and you may be questioned.
In this case, we ask that you tell the technologist so that he or she gives you a document that explains to the customs officials the reasons behind your radioactivity.
What do we do with the images?
Even if a lot of information is measured by a computer on these images, the most important one is the measure of the fraction of the left ventricle’s ejection, that is, the percentage of blood that the heart’s left side pushes into circulation at each heartbeat.
This number is usually higher than 50%.
This is what a nuclear medicine specialist sees.
The other important element is the evaluation of the movements of each section in 3D.
We might as well say that we let the specialist understand and interpret these types of images!
The power ofthe exam
The exam is powerful in the sense that it is precise to measure and to quantify the fraction of the left ventricle’s ejection no matter your corpulence.
It is not appropriate, however, to evaluate the small heart details like the functioning of the valves or of the arteries of the heart, for example.