Magnetic Resonance Imaging
(MRI) is a way of creating detailed images of your internal
MRI scans are not currently available
at all hospitals in the UK but they are becoming more readily
What is a cardiac MRI Scan?
During a cardiac MRI scan an MRI machine uses
magnetic and radio waves to create clear pictures showing the
inside of your heart. Unlike an X-ray, an MRI scan does not use
What can a cardiac MRI show?
A cardiac MRI scan is used to view your
heart’s structure and to assess how well it’s pumping. This is
useful if you have structural problems with your heart such as
congenital heart disease or age-related wear and tear of your
heart valves. If you have heart
failure, the scan can help your doctor to determine the amount
of healthy heart muscle.
Because MRI scans can also be used to study
the blood supply to your heart, they can help your doctor to
investigate conditions such as
coronary heart disease, and estimate the damage to your heart
after a heart
What happens during a cardiac MRI scan?
- You lie on a bed, which then moves inside a tunnel-shaped
scanner that is open at both ends.
- You will be asked to lie still while the scan is taking
- The scan may last for up to an hour, but there’s a buzzer you
can press if you need to speak to the radiographer (the person
operating the scanner).
- The scanner is quite noisy – you’ll be able to hear banging
sounds – but you’ll usually be offered earplugs or better still,
earphones so you can listen to music and relax
- Because it’s important to stay still during the scan, babies
and young children are often given a general anaesthetic before an
- For some cardiac MRIs the doctor will use a dye known as
contrast agent to enable images of the blood flow to your heart
show up more clearly on the scan. The dye will be injected
into a vein in your arm before the scan starts. Your doctor
will give you more information about this if it is required.
The test is pain free, but if you’re
claustrophobic (afraid of being in small spaces), tell your doctor
before the test. You may be offered a mild sedative - a
drug to help you relax.
You should be able to go
back to your normal activities straight away. A cardiac MRI
scan is usually an outpatient procedure, which means that you will
not have to stay in hospital overnight.
- If you have been given a sedative you will not be able to drive
and will need to be taken home by a friend or relative. You
will not be allowed to drink alcohol or operate machinery for 24
- If you have been given an injection of a dye (contrast agent),
it is a good idea to drink a lot of water for the following 24
hours to help flush the dye out of your body.
- It is unlikely that the results of your scan will be available
immediately. Usually the doctor who arranged the scan will discuss
the results with you a couple of weeks after the scan.
Is a cardiac MRI suitable for everyone?
You can’t have an MRI scan if you have a
implantable cardiac defibrillator (ICD), inner ear
implants or any type of surgical foreign body such as a metal clip
in the brain or eye. That’s because the scanner uses very
strong magnets which could deactivate the pacemaker or
defibrillator and cause anything made of metal to move.
If your kidneys aren’t working well, the dye
used during the scan could cause further damage. Your doctor will
take a blood test before the scan to check your kidney function,
and explain the risks and benefits to you.
Researching cardiac MRI
Your money helps us
fund hundreds of top scientists all over the UK, including the
work of Dr John Greenwood, whose team
is working on research that will help doctors use cardiac
MRI scans to safely and accurately diagnose coronary heart