What are the possible risks?

As the scanner consists of a powerful magnet, it may attract certain metallic objects. You must not have a scan if you have had metallic objects or medical devices (e.g. pacemaker) inserted into your body during an operation.
The scan involves lying flat in a slightly confined space and a small number of people find this too claustrophobic.
If you are pregnant or breast-feeding, you should not take part because the MRI and gadolinium used in this study may harm an unborn or nursing baby.
Gadolinium contrast dye is used for CMR and may occasionally cause headache, mild rash and very rarely a more severe allergic reaction. In people with healthy kidneys, gadolinium is removed from the bloodstream within a few hours. We will check your kidneys before we start if you are at risk of kidney disease and have not had your kidney function tested recently.
Some people find the cannula (plastic tube) in the arm uncomfortable, and there can be bruising at the site of needle entry.
In rare cases the ECG sticky pads can lead to skin irritation.