An MRI scan uses magnetic and radio waves to make pictures of the inside of your body.
You will be asked to lie in a short tunnel, which houses a special magnet. Short bursts of magnetic fields and radio waves are sent through your body. This takes about 30 to 45 minutes and you will need to lie still. The machine may make a moderate banging noise while it is working, which might be unpleasant to some people. However, the MRI scan is completely painless and harmless since radiation is not used.
The images will show very detailed pictures of the structure of your heart and blood vessels. The MRI can also measure the flow of blood through your heart and some of your major arteries.
From the scan your doctor can tell if your heart is not working properly and locate any problems with the structure of your heart.