A cardiac MRI uses strong magnetic fields and radiofrequency waves to capture images of your organs. These images can be 2-dimensional (2D) or 3-dimensional (3D) and show a detailed, cross-sectional view of the scanned area. Your cardiologist can use these images to check for structural abnormalities in the heart that may affect heart function.
Gadolinium-based contrast dyes may also be given intravenously for a cardiac MRI. The dye helps improve the image's contrast, making the details clearer. This allows your cardiologist to better differentiate the layers of heart tissue and blood vessels, allowing for a more accurate diagnosis.
A cardiac MRI helps your cardiologist check for structural abnormalities in your heart and nearby blood vessels. Some conditions which your cardiologist can diagnose using MRIs are:
Apart from diagnosing heart diseases, a cardiac MRI can also be used to:
Your cardiologist will order a cardiac MRI if:
Cardiac MRIs can achieve a level of detail often not seen in other imaging scans. Together with the contrast dye, cardiac MRIs allow doctors to see small features of the heart from various angles and in great detail, resulting in a more accurate diagnosis.
MRIs use strong magnetic fields, which are much safer than ionising radiation. The test is also virtually pain-free and can even be done for most pregnant patients.
However, you must remember to inform your doctor about your pregnancy, as the contrast dye may harm your baby. This will allow your cardiologist to take appropriate measures to ensure you and your child can undergo the MRI safely.
Due to the strong magnets used during an MRI scan, a cardiac MRI may not be suitable for those who have metal-based implants such as:
An important point to note is that specific models of pacemakers and ear implants may be MRI-safe. To find out if yours is, check with your cardiologist before booking a scan.
MRIs also require patients to stay still in a small enclosed place for 30 minutes to 2 hours, so you might not be suitable for MRIs if you:
Finally, the gadolinium-based contrast dye used for cardiac MRIs could also:
If you have any of the above conditions or concerns, discuss them with your cardiologist before booking a cardiac MRI scan. Doing so will help ensure your safety and improve the quality of images obtained from the scan.
If you have high concentrations of metallic components in your tattoo paint, going for an MRI could mean a burn or pulling sensation in that area due to the strong magnetic fields in an MRI machine. The good news is that this very rarely occurs, mainly if your tattoos cover less than 5% of your body.
However, you can ask your tattoo artist about the ink they used before booking a scan. Let the MRI technologist know about your tattoos beforehand so they can look out for any side effects during the scan.
Like a regular MRI, there are a few things you have to take note of before going for a cardiac MRI:
Your cardiologist will inform you if you need anything else for the cardiac MRI in addition to these basic preparations.
Refrain from using deodorant or cosmetic products, as some might contain metals that can be affected by the MRI magnets and interfere with the scan. This also extends to makeup, hairspray, and sunscreen.
Transdermal medicated skin patches are not recommended as they may contain bits of metal in their non-adhesive areas. These metal bits can induce a burn at the adhesion site during an MRI scan.
However, if you have to constantly wear a skin patch for medical reasons, inform your cardiologist about the patch and your reasons for wearing it before booking a cardiac MRI.
There would be no need to arrange for anyone to help after the cardiac MRI unless sedatives were used to keep you calm during the scan.
You should arrive at least half an hour earlier before the scan. Then, at the clinic, you can expect the following:
A cardiac MRI will take about 30 minutes to 2 hours. No overnight hospital stay is required before or after the test.
If you were not given any sedatives, you can resume all daily activities immediately after the scan. You will not need to stay in the clinic or arrange for someone to transport you home.
If you were given sedatives or anti-anxiety medication, you might need to stay in the clinic for a short while until the medication wears off or go home via arranged transport.
However, to be sure, you can always ask your cardiologist if there is anything you should look out for before you leave the clinic.
The results will require a few days to process and will be discussed at your next consultation. During your follow-up, your cardiologist may also:
Cardiac MRI scans are becoming increasingly popular as they do not use ionising radiation, require little to no preparation beforehand and are painless.
However, cardiac MRIs are not all-encompassing. Other tests, such as an echocardiogram and blood pressure monitoring, may be carried out to provide a more comprehensive diagnosis. This helps ensure that the heart's function is fully assessed and any treatment received is fully tailored to the patient’s needs.
We hope that this helps you better understand cardiac MRIs and how to prepare for one the next time you need a scan!
Dr Devinder Singh is the Medical Director of Cadence Heart Centre. He is an experienced Senior Consultant Cardiologist & Cardiac Electrophysiologist with over 20 years of clinical experience.
His expertise lies in clinical cardiology, cardiac rhythm disorders (arrhythmia), cardiac pacing (including cardiac resynchronisation therapy) and cardiac magnetic resonance imaging. He performs electrophysiology studies and radiofrequency ablation of cardiac arrhythmias, and is well versed in pacemaker and defibrillator insertions.
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