Magnetic resonance imaging (MRI) is a type of imaging that uses a strong magnet to make the tiny magnetic atoms of our body (called "Protons") line up. Once alligned we can control their behavior using radiowaves. Essentially, by playing different "music" over these radiowaves we can your protons "dance" in different ways. This makes MRI a remarkably unique tool as we are able to make your body tell us different information about what is wrong with it, simply by composing new types of "music". Over the past 15 years a wide range of this music has been composed specifically to look at heart problems. This now allows us to look at how the heart muscle thickens and the valves move, how blood flows through the heart and also into the muscle, and to check whether the heart muscle has been damaged. One unique advantage of MRI is that all this can be done without the use of any radiation.
A Cardiac MRI can take from 30 minutes to 90 minutes depending on what questions have been asked by your doctor. During this time you are lying comfortably on your back and will be in constant contact with the MRI technologist.
Since an MRI machine uses magnetic and radio waves rather than radiation there are no risks from exposure to the scanner during the procedure.
MRI is considered safe during pregnancy, but if you are pregnant or suspect you may be pregnant you should notify your doctor and discuss any potential risks and benefits of an MRI procedure.
The MRI machine produces very strong magnetic fields so the procedure may not be safe for patients who have metal implants or objects located in sensitive areas of the body, such as in the brain or in the eye. Most metal implants are compatible with having an MRI, but some are not. Therefore we ask patients to inform us of any metal devices or prior surgeries before coming to the MRI unit. We also ask patients to complete a screening questionaire when they arrive.
There are no specific requirements for eating or drinking before a cardiovascular MRI procedure. You can eat, drink, and take your medications as normal. The one exception is for a specific type of Cardiac MRI called a "Stress Perfusion Scan" - for this test the booking clerk will ask you to stop consuming Caffeine for 24 hours prior to the MRI as it interferes with this test.
Before your cardiovascular MRI procedure you will be asked by a Stephenson Centre team member if:
You will be able to leave the MRI Centre immediately following the test. If an MRI contrast agent was used during your procedure, nearly 100% of this will be cleared from your body within 72 hours. We generally recommend to stay well hyrdrated during the first 24 hours.
Your doctor will receive the results of the test within 48 hours. They will receive this through the hospital medical record system and also through the Provincial medical record system (NetCare).
Contrast agents rather than "dyes" are used during cardiovascular MRI procedures. This contrast agent helps to highlight the heart and blood vessels and shows areas of damage. The contrast used is called Gadolinium and is NOT the same as the iodine-containing contrast agents used for x-ray or CT procedures.
The contrast used in MRI is cleared by your kidneys, typically within 72 hours. Unlike other contrast agents (ie: iodinated dye) our contrast will not cause significant drops in kidney function when given. However, if your kidney or liver function is already very low then the use of this contrast can be associated with a rare condition called Nephrogenic Systemic Fibrosis (NSF). Therefore, please let us know if you have significant kidney or liver disease.
Allergic reactions to the contrast are very rare. If you have any allergies or sensitivities to this particular contrast please let us know.
Canadian Society of Cardiovascular Magnetic Resonance (CanSCMR)
John Hopkins Medicine Information about MRI
National Heart, Lung, and Blood Institute Information about MRI
