Magnetic resonance imaging (MRI)

The MRI scanner uses large magnets and radio-frequency waves to create pictures of the body's internal structures. No x-rays are involved. 

Cardiac MRI is a test that makes very clear and detailed movies or pictures of the beating heart and great vessels.

Your heart doctor uses the cardiac MRI to accurately understand: 

• The structure of the heart and the chest 
•  How well the heart is pumping, and whether there is any damage
• The correct diagnosis of any heart disease, such as: 
  • Ischemic heart disease/disease of the coronary arteries causing heart attacks 
  • Heart failure
  • Heart muscle disease (cardiomyopathies)
  • Aorta disease, aortic valve and mitral valve disease
  • Congenital heart disease
  • Pericardial heart disease
  • Right heart disease

Preparing for your scan

There are a few things that you can do before your scan to help you prepare: 

• Eat something light
• Take your medications as normal, unless you are having a stress CMR scan
• If you are having a stress CMR, it's important to not have any caffeinated drinks for 24 hours beforehand.
• If you are claustrophobic let us know when you are booking your scan appointment. That will give the bookings team time to assess whether or not you would be able to have your MRI safely with sedation ( a medication to help you relax). 
• MRI scanners use very powerful magnets to make the images needed, so you must not bring any metal items in with you into the magnet room. You must also tell staff if you have any metal implants or metal under the skin. (Most metallic implants, such as sternal wires and mediastinal clips used for heart surgery have been designed to be used for MRI and are no problem.)
• You must tell staff if you have the following: 
  • implanted pacemaker or defibrillator 
  • cerebral aneurysm clip (metal clip in a blood vessel in the brain)
  • pregnancy
  • implanted insulin pump, narcotic pump or implanted nerve stimulators (TENS) for back pain
  • metal in the eye or eye socket
  • cochlear (ear) implant for hearing impairment
  • some stents (while most stents are safe, some might not be)
• Complete the safety questionnaire we send when we send your appointment letter
• Wear a top that you can easily remove (women should also wear a bra that can easily be removed)
• You can wear metal-free trousers such as jogging bottoms with elastic bands, during the scan
• We will provide you with a gown
• We will ask you to remove: 
  • belts with buckles
  • clothes with metal zippers or fasteners
  • watches 
  • wallets with bank or credit cards with magnetic strips 
  • jewellery 
  • hair accessories (except elastic bands)

What to expect during your scan

An MRI radiographer or assistant will help you prepare for your scan. They will: 

• check your safety questionnaire with you, and then ask you to sign it
• let you get changed into your hospital gown
• place small electrode stickers on your chest and back. Men may have their chests partially shaved to help the electrodes stick. These are then attached to an electrocardiograph (ECG) monitor, which monitors your heart's electrical activity during the test
• insert an intravenous (IV) cannula into a vein in your arm for non-iodine based contrast (dye) to be injected during the scan
• show you how to operate the intercom and alarm bell system. The MRI scanner has a long tunnel that scans your body as you lie on a moving table. This system will let you speak to the scanner operators during the test. 
• give you headphones for your scan as it will muffle the normal knocking sounds that the magnet makes
• ask you to lie as still as possible. For CMR scans, the radiographer will ask you to hold your breath periodically for 6-10 seconds to create clear pictures of your heart. 

The MRI scan normally takes between 30 to 75 minutes, depending on what images are needed from the scan.

After your MRI scan

If you received a sedative, we will let you know when you can eat, drink and return to normal activities. You also need to have someone who can drive you home. 

If you did not have any sedation, you'll be able to resume your normal routine and diet immediately. 

Your consultant will discuss the results of the test with you.