Understanding diagnostic tests
Magnetic Resonance Imaging (MRI)
An MRI produces detailed pictures of the brain’s structure. It can help the healthcare team investigate possible causes of seizures and plan treatment.
About this information
This webpage is subject to continuous review by Epilepsy Ontario to help keep the information current. This material is for informational purposes only and should not be used for self-diagnosis or as a substitute for professional medical advice, diagnosis, or treatment. Consult your healthcare provider about your own health and care.
Why might an MRI be recommended?
MRI uses a strong magnetic field and radio waves to create images. It does not use ionizing radiation.
In epilepsy care, MRI may help identify structural changes that could be relevant to seizures. A specialist may request a particular epilepsy imaging protocol.
A normal MRI does not rule out epilepsy. Some people with epilepsy have no structural change visible on the scan.
Tell the MRI team before your appointment
Implants and metal need screening.
Tell the team about all implanted devices, previous operations, and any metal fragments in your body. Bring your implant identification card if you have one.
- Pacemakers and other cardiac devices.
- Vagus nerve stimulators and other neurostimulators.
- Cochlear implants, pumps, clips, or other implanted equipment.
- Previous metal injuries, especially involving the eyes.
An implant does not automatically prevent MRI. Some devices can be scanned only under specific conditions. The MRI team must confirm what is safe for your exact device.
Pregnancy and breastfeeding: Tell the team if you are pregnant, might be pregnant, or are breastfeeding. Pregnancy does not automatically rule out a medically necessary MRI. Contrast use requires a separate assessment.
Before your scan
Follow the centre’s instructions about clothing, removable items, food, drink, and medication. Tell them about claustrophobia, pain, difficulty lying still, kidney problems, and previous contrast reactions.
If sedation is planned, follow the specific fasting, supervision, and transportation instructions provided.
During the scan
You lie on a table that moves into the scanner. Remaining still helps produce clear images.
The scanner makes loud knocking sounds. Hearing protection is provided, and you can communicate with the team.
If contrast is needed
Some examinations include an injection of gadolinium-based contrast. It is not required for every brain MRI.
The team will explain why it is being considered and review relevant risks.
Other MRI techniques
Functional MRI (fMRI)
Uses changes related to blood flow to help map functions such as language or movement, sometimes while you perform tasks. It may contribute to surgical planning.
Magnetic resonance spectroscopy (MRS)
Provides information about selected chemicals within brain tissue. It may be used for particular clinical questions.
After your scan
Follow the discharge instructions, particularly if you received sedation. A radiologist reviews the images and sends a report to the referring healthcare provider.
Ask how you will receive the results and whether any further assessment is needed.
