Cardiac MRI relies on technology that uses powerful magnets and radiofrequency waves to provide very detailed images of the heart and blood vessels on a computer.
It’s a non-invasive test that can provide a clearer picture than alternative imaging techniques such as X-rays and CT scans. It may be recommended for you if the images gained from alternative techniques are not clear enough because of your build – for example, if you’re very overweight or obese, or if you have large breasts, or if you have an associated condition that makes imaging difficult. Cardiac MRI is also useful in examining congenital heart defects.
If there are concerns that some aspect of your condition may require more detailed imaging, cardiac MRI may be recommended. It may also be useful if there’s a medical reason to avoid more invasive tests, or having several tests rather than one.
The machine will be calibrated and used differently depending on the condition it is being used to detect. In some cases, you’ll receive a small injection of a contrast agent called gadolinium, which enables the technician to see the heart and blood vessels more clearly.
People with an implanted pacemaker or defibrillator can’t have an MRI scan.
An MRI takes place in a large cylindrical, tube-like machine. You’ll be asked to remove your clothing and especially any metal objects such as hairpins, jewellery, watches and so on, which will be affected by the very strong magnets in the machine. Once that is done, you’ll be given a hospital gown and asked to lie on an examination table that is slid into the tube, which will then be closed.
During the procedure – which can take 30 minutes to an hour – you will be asked to lie very still, and may at times be asked to hold your breath while the technician takes pictures of your heart.
When the procedure is over, the technician will slide you out of the machine and you can resume your normal activities.
Cardiac MRI can effectively establish the size and thickness of the chambers of the heart, the efficiency of its pumping function, the extent of any damage from previous heart attacks, and detect narrowing and blockages in the coronary arteries.
This information is then used to determine the best treatment options.
Cardiac MRI is a very low risk procedure.
Because of the strong magnets used in MRI, if you have a pacemaker or implanted defibrillator, you can’t have the test. Similarly, if you’ve had a stent implanted within six weeks of the procedure, you shouldn't have an MRI.
Some people feel claustrophobic when surrounded by the MRI machine and having to lie still for an extended period. If you think that you’ll have a problem, discuss this with your doctor beforehand so that arrangements can be put in place to help you to cope.
This information has been developed and reviewed for Bupa by health professionals. To the best of their knowledge it is current and based on reputable sources of medical research. It should be used as a guide only and should not be relied upon as a substitute for professional medical or other health professional advice.
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Last published 31 October 2011