Cardiac MRI: how is the exam performed?
What is a cardiac MRI?
Cardiac MRI is an MRI scan focused on the heart. It is mostly often used to find abnormalities in the heart muscle (myocardium).
Synchronization with the electrocardiogram makes it possible to freeze the movements of the heart by capturing precise phases of the cardiac cycle, in order to obtain clear images of the myocardium and to study, among other things, the strength of its contraction (contractility) or its blood supply.
What is a cardiac MRI used for?
Cardiac MRI is often used to study the blood flow or viability of the heart muscle, especially when there is partial or total obstruction of a coronary artery.
The cardiologist may also order an MRI scan to look for malformations, or diseases of the heart muscle (cardiomyopathies), or sometimes for other reasons (looking for inflammation, abnormal infiltration, clot or tumor, study of the pericardium, valves or aorta).
How is the exam carried out?
You will be greeted on your arrival by a secretary who will ask for your prescription.
A detailed form, sent with your appointment notification, , will be completed with a consultation during preparation, and you will be informed of and checked for the absence of contraindications to the examination.
After being called to the waiting room, you will be taken to a booth to undress.
Once in the booth or on the machine table, a technician will place electrodes on your chest for an electrocardiogram.
The radiologist might administer medication to speed up your heart rate if a stress MRI is requested.
The examination lasts about 20 minutes and requires the injection of intravenous gadolinium-based contrast product.
The radiologist will give you the result verbally immediately after the examination. You will then leave with the images and your report.
What are the risks associated with the exam?
Cardiac MRI is an imaging scan with magnetic field without irradiation.
Contraindications are those of MRI and include ferromagnetic implantable devices (i.e. most pacemakers, except some recent models which are compatible after specific adjustment by the rhythmologist).
The examination requires the injection of a gadolinium-based contrast product with a very low risk of allergy. A coronary vasodilator (Regadenoson) injection is necessary if you are required to perform a stress MRI to accelerate your heart rate (stress test equivalent).
An electrocardiogram and a blood pressure reading are taken before the examination to check for a contraindication. This medication may cause symptoms such as heat in the chest, or a small respiratory discomfort that quickly regresses when the administration of the medication is stopped, or after injecting the antidote. More severe effects are rare (1 case out of 1500): chest pain, hypotension, arrhythmia.
How to prepare well for a cardiac MRI?
The following products should be avoided on the day of the exam: coffee, tea, chocolate, cola, banana.
It is advisable to read the information sheet sent to you with the appointment notification, and bring any previous cardiac examinations (ultrasound, scintigraphy, coronary angiography for example).
The prescription from the cardiologist or prescribing doctor is essential.