What happens during a cardiac MRI?

Transcript

When patients present with symptoms such as chest pain, breathlessness, palpitations or unexplained heart failure, conventional tests such as an ECG and an echocardiogram may not provide sufficient data for us to be able to fully explain what's going on. That's where cardiac MRI steps in. Cardiac MRI is considered the gold standard imaging modality to assess heart structure and function and critically to provide information on tissue characterisation.

By that I mean what the heart muscle is made of. Is it scarred? Is it damaged?

Is it inflamed? Cardiac MRI plays an increasing role in a majority of our patients presenting to our clinic. It is critical in helping us to understand and diagnose a range of conditions including cardiomyopathies which are a form of heart muscle disease as well as myocarditis and pericardial disease.

Critically it does all of this without using any ionizing radiation whatsoever. For example, in cases of conditions such as myocarditis, cardiac MRI can detect areas of oedema and inflammation. This is something no other test can do.

For that reason, cardiac MRI is considered critical in diagnosing myocarditis. Additionally, another large application is the use of stress cardiac MRI to detect possible underlying obstructive coronary artery disease. Stress cardiac MRI can detect areas where the heart isn't getting adequate blood supply.

This is a condition we call myocardial ischaemia. I'd now like to tell you what actually happens on the day of your cardiac MRI. When you arrive at our imaging unit, you'll first check in and be greeted by the MRI team.

They'll explain the procedure to you and ask them safety questions such as whether you've had any metal implants or devices like a pacemaker. If you are having a stress cardiac MRI, they will ensure that you have not had any caffeine for 24 hours. Next, you'll change the hospital gown and remove any metal objects like jewelry or belts.

A small cannula will usually be placed in a vein in your arm as most cardiac MRIs involve injecting a contrast dye called gadolinium. This helps highlight your heart structures. You'll then lie on a flat table that slides into the MRI scanner which looks like a large tunnel.

It's important to stay as still as possible during the scan to get clear images. The scan is painless but the machine can be noisy. You'll hear loud tapping or humming sounds and you'll be given headphones or earplugs.

You'll be asked to follow simple breathing instructions like hold your breath for a few seconds at a time. The entire process can take around 30 to 60 minutes. If you're having a stress MRI, a doctor will inject a medication called adenosine that speeds your heart up for four minutes.

You will feel like you're exercising for those four minutes before the effects of the adenosine subside. Once it's done, you'll be monitored briefly after the contrast injection and then you can go home the same day and resume normal activities. The results are reviewed by a cardiologist and we will discuss the findings with you at a follow-up appointment.

I hope you can now see that cardiac MRI plays a critically important role in managing patients with cardiovascular disease.