A cardiac magnetic resonance imaging (MRI) stress test is used to view heart tissue and anatomy in two dimensions to determine whether the coronary arteries are stenotic under medication-induced stress. 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.
60 to 90 minutes
- When you schedule an appointment, you will be advised whether a blood test is required before the exam (if a contrast agent has been requested).
- It is mandatory for the patient to fill out a questionnaire before the appointment, as there are some contraindications for an MRI exam.
- All sources of caffeine (tea, coffee, chocolate, etc.) must be avoided for at least 24 hours before the exam. However, a very light breakfast may be eaten on the morning of the exam. When you schedule an appointment, you may be asked to stop beta-blockers (medication that regulates the heart rate).
- Patients must remove any metal from their person, which includes jewellery, piercings, hair clips, etc., and put on a hospital gown.
- 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. 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.
In the middle of the exam, a medication will be injected to dilate the coronary vessels and activate heart function.
Again, the technologist will explain the effects and give instructions.
Generally, this period lasts 6 to 15 minutes depending on the type of medication used (chosen by the cardiologist on the day of the exam). If a contrast agent will be injected during the exam, the technologist will give instructions.
- The exam will be analyzed and read in the week following the appointment. The report will be sent to the treating physician.
- The report should be ready in 2 weeks. 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.