Dr Matthew Webber
Heart Failure, Cardiac Devices and Advanced CMR Specialist
Cardiac MRI
What is a Cardiac MRI?
Cardiac MRI (CMR) is one of the most advanced ways to examine the heart. It uses an MRI scanner (a powerful magnet) to create highly detailed images of the heart’s structure, function, and tissue health.
Unlike many other tests, cardiac MRI does not use radiation. Instead, it uses magnetic fields and radio waves to produce precise images that allow doctors to assess how the heart muscle is working and whether there is any underlying damage or inflammation. It is therefore safe to have multiple scans without any harm to the body.
Cardiac MRI is widely regarded as the ‘gold standard’ imaging test in cardiology for assessing heart muscle disease.
I am Level 3 accredited in CMR, the highest level of specialist certification allowing me to perform and interpret these scans for a wide range of heart conditions.
What to expect?
Before
Cardiac MRI scans usually take 30–45 minutes.
When you arrive, we will complete a short safety checklist. ECG stickers will be placed on your chest to monitor your heartbeat, and a small cannula may be placed in your arm if contrast dye is needed.
You will lie on the scanner bed, which moves into the MRI scanner. The scanner is open at both ends and you can speak to the team throughout.
During
While the scan is taking pictures, you’ll hear rhythmic tapping sounds from the machine. This is completely normal, and we’ll provide earphones to make it more comfortable.
At certain points we’ll ask you to hold your breath for a few seconds (usually 5–10 seconds) while we capture some of the images.
After
Once the scan is complete you can usually return to normal activities straight away.
Your images will then be carefully analysed and a detailed report prepared for your referring doctor.
Contrast dye
For many cardiac MRI scans we use a contrast dye called gadolinium. This helps us see certain features of the heart more clearly, such as areas of scarring, inflammation, or subtle changes in the heart muscle that might not otherwise be visible.
The contrast is very safe and is naturally cleared from your body by the kidneys.
Stress scans with adenosine
Some Cardiac MRI scans also include a stress test using a medication called adenosine. This is given through the cannula in your arm for a few minutes during the scan.
Adenosine temporarily increases blood flow through the heart. This helps us identify whether there are areas of reduced blood supply, which can occur if the coronary arteries are narrowed.
While the medication is running, it’s common to briefly feel:
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Warm or flushed
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Slightly short of breath
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Pressure in the chest
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A little light-headed
These sensations are normal and pass very quickly—usually within seconds of the medication stopping. Our medical team will monitor you closely throughout the scan to make sure you remain comfortable and safe.