What is a CMR scan?

A cardiac magnetic resonance (CMR) scan is non-invasive and shows detailed images of your heart as well as the surrounding blood vessels, using strong magnets and radio waves.

You might need cardiac magnetic resonance imaging (MRI) if you have symptoms which may suggest a heart problem, such as shortness of breath, chest pain or fainting.

What does a cardiac MRI show?

A cardiac MRI scan uses magnetic and radio waves to produce high-resolution moving and still images of the chambers, valves and muscles of the heart, and the flow of blood through the heart, to show how well it is working. There is strong evidence to support the use of cardiac MRI in complex cases, or for diagnosing conditions that other tests have failed to identify.

A cardiac MRI is thought to be the best test to diagnose many common as well as rare heart conditions. By showing detailed images of different parts of your heart, and looking at your heart’s blood supply, CMR can diagnose various heart conditions, including:

  • heart muscle damage or reduction in blood supply (e.g. from coronary artery disease and heart attacks)
  • heart failure or an enlarged heart
  • heart inflammation or inflammation of the lining of the heart (pericardium)
  • hypertrophic cardiomyopathy (thickening of the heart muscle) or other inherited heart muscle disease conditions
  • heart valve disease
  • problems with the aorta
  • congenital heart disease 
  • cancer

Preparation for your cardiac MRI

Before your cardiac MRI scan, you will be asked to complete a questionnaire to ensure you are suitable for the procedure, which involves exposure to a strong magnet.

If you are undergoing a cardiac stress perfusion MRI, you will be asked to avoid caffeine for 24 hours before the test, as caffeine can interfere with how the medication (adenosine) with which we exercise your heart works.

A cardiac MRI scan may not be suitable for:

  • people who are claustrophobic
  • those who are obese and are uncomfortable lying inside the scanner
  • patients with very old implanted pacemakers or certain medical devices

What happens when you have a CMR scan?

The exam starts with ​electrocardiogram (ECG) leads being placed on the chest, to help guide us with information from your heartbeat and breathing, when we make the images.

You will be asked to lie on your back inside the doughnut-shaped MRI scanner for usually 45-60 minutes depending on how complex the study has to be. As the magnet will make a knocking sound, you will be given headphones. You will be asked to lie still and hold your breath – for up to 10 seconds – several times during the scan while the pictures are made.

During the CMR exam, you may be given an injection of gadolinium, a contrast agent (a special dye) which highlights tissue structures inside the heart. This is injected through an IV line in the arm.

A cardiac MRI scan does not hurt, and if your doctor decides it is safe for you to have a cardiac MRI, the MRI itself does not use any radiation and poses no significant risks.

How long does a cardiac MRI take?

Due to the advanced technology used, an MRI takes longer than a normal X-ray to carry out. The scan typically takes between 45-60 minutes but can take up to 90 minutes.

The time the scan takes will vary according to the type of problem that is being investigated; it will take longer to investigate complex heart conditions.

CMR results

The CMR results are usually available within a few days. How long your CMR results may also vary according to several factors, including:

  • how complex the CMR scan is
  • whether the results need to be compared with the results of any previous imaging tests you’ve had
  • whether more information is needed before a cardiologist can interpret the exam

The hospital or clinic where you have your cardiac MRI will be able to advise you on when the results of your scan are likely to be ready.

Once the results are ready, you can discuss them with the doctor who referred you for the scan in person or over the telephone. If a treatment or intervention is required as a result of the test identifying a heart condition, your doctor will talk you through the next steps.

Cardiac MRI pricing

The cost of your cardiac MRI scan will vary according to the complexity of the condition being investigated, and whether any special measures (such as a contrast agent) are required.

Pricing is as follows:

  • Cardiac MRI scan: from £2,243 (£2,768 with contrast)
  • For MRI of areas of the body outside the heart itself: from £844 – £2,682
  • CMR angiography: from £3,166 (£3,825 with contrast)

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