Magnetic Resonance Imaging (MRI) is a
way of creating detailed images of your internal organs, such as
your heart and blood vessels.
As MRI machines are not
currently available at all hospitals in the UK, you may be referred
to a different hospital if you require an MRI
scan What is a cardiac MRI
What is a cardiac MRI Scan?
A cardiac MRI scan is a non-invasive test that
uses an MRI machine to create magnetic and radio waves to create
clear pictures showing the inside of your heart. Unlike an X-ray,
an MRI scan does not use radiation.
What can a cardiac MRI show?
A cardiac MRI scan is used to view your
heart’s structure (the muscle, chambers and valves of the heart)
and to assess how well it’s pumping. A cardiac MRI is useful for
checking structural problems with your heart, such as:
MRI scans can also be used to look at the
blood supply to your heart. They can help your doctor to
investigate conditions such as:
What happens during a cardiac MRI scan?
- You lie on a bed, which then moves inside a tunnel-shaped
scanner. The scanner is open at both ends.
- You’ll 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.
- As it’s important to stay still during the scan, babies and
young children are often given a general anaesthetic before an MRI
- For some cardiac MRIs the doctor will use a dye known as
contrast agent so that the images of blood flow to your heart show
up more clearly on the scan. The dye will be injected into a vein
in your arm. Your doctor will give you more information about this
if it’s 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.
What happens after the scan?
Most people that have a cardiac MRI scan will not have to stay
in hospital overnight. You should be able to go back to your normal
activities straight away. Some exceptions to this are:
- If you’ve been given a sedative, you won’t 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 hours.
- If you’ve been given an injection of a dye (contrast agent),
it’s a good idea to drink a lot of water for the following 24 hours
to help flush the dye out of your body.
It’s 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:
This is because the scanner uses very strong
magnets that 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. You may need some fluids
through a ‘drip’ in your arm before the MRI scan if you have kidney
How can I prepare for the test?
- Talk to your doctor if you have any medical
implants (such as a pacemaker), stents or are pregnant before the
- Most people can eat normally and continue
taking any medication before the test.
- Remove all electronic devices and
credit/debit cards from your pocket. The magnets used in the
machine can damage these items.
- Take off all metal objects such as jewellery,
watches and hearing aids.
Help fund our research on 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 disease.