Cardiac magnetic resonance imaging (MRI) is conducted to view heart tissue and anatomy in two or three dimensions using radio waves. The MRI technique captures the signals emitted by hydrogen protons, which become aligned when the body is placed under a powerful magnetic field and when they are excited by radio frequencies (they “resonate”).
45 to 90 minutes
- A blood test may be required before the exam if a contrast agent has to be injected.
- It is mandatory for the patient to fill out a questionnaire before the appointment, as there are some contraindications for an MRI exam.
- Patients must remove any metal from their person, which includes jewellery, piercings, hair clips, etc., and put on a hospital gown.
- All sources of caffeine (tea, coffee, chocolate, etc.) must be avoided for at least 24 hours before the exam.
- Areas of the chest may require shaving before the electrodes are placed.
- If an injection is required for this exam, one (or two) IVs will be inserted and left in place for the entire exam.
Patients lie down on their backs throughout the exam. Electrodes are connected to a small device. If an injection is required, an automatic injector is connected to the IV. An antenna that looks like a plate is placed on the chest.
The MRI machine looks somewhat like a tunnel open at both ends, and the body part that is being scanned has to be at the centre of the tunnel. A technologist gives patients instructions on when to hold their breath and communicates with them during the exam. Some patients may feel heat, which is a known effect of radio waves, but this is harmless.
The technologist will also give instructions if the patient will be injected with a contrast agent.
- The exam will be analyzed and read in the week following the appointment. The report will be sent to the treating physician. A minimum of two weeks is generally required for the report to be ready.
- There are no side effects of the exam, as no ionizing radiation is used. The only exposure is to radio waves and a magnetic field.
- However, there are absolute and relative contraindications for this exam, which are checked when the appointment is scheduled and on the day of the exam. Therefore, pregnant and breastfeeding women or anyone who has a metallic implant must advise the agent at the Scheduling Centre, who will communicate this information to the right person.