What an MRI scan does
What it involves
How you might feel during your MRI scan
After your MRI scan
People who might have an MRI scan
Before your scan is ordered
An MRI scan may not be useful for everyone
How to get an MRI scan
MRI stands for magnetic resonance imaging. An MRI scan uses a strong magnetic field and radio waves to create pictures on a computer, of tissues, organs and other structures inside your body.
Some people have epilepsy because they have some damage in their brain. This may have been caused by scar tissue from an illness or a brain injury. An MRI scan is used to show this type of damage.
The MRI scanner is like a tunnel. It is about 1.5 metres (5 feet) long and is surrounded by a large circular magnet. You lie on a bed, which then slides into the open-ended scanner. During the scan, the MRI will send images of your brain to a computer, which will show different types of brain tissue in different colours.
The MRI scan itself is not painful. The radiographer who does the scan might need to inject you in your hand or arm, with a harmless dye. This is to make the tissue show up as clearly as possible. A few people have had allergies to the dye, so the radiographer will ask if you have any allergies first.
You need to keep still while you are being scanned, otherwise the scan picture may be blurred.
The MRI scan can take up to an hour.
The MRI is noisy when it is scanning but you will be given earplugs or headphones to protect your hearing. The inside of the scanner is like a hollow open-ended tube. You might find this worrying if you are uncomfortable in confined spaces. You may be given a buzzer to hold, so that you can let the radiographer know if you feel uncomfortable during the scan.
To help you to relax, you might be able to listen to music, or watch a DVD while the scan is done. A relative or friend might be able to go into the room with you.
If you feel nervous, or can’t keep still while the scan is being done, you could be offered medicine to help you relax or sleep. Young children and people with learning disabilities may need a very light general anaesthetic to make sure that they keep completely still during the scan.
After your scan, a radiologist will read the pictures taken by the MRI. They will then send your results to the doctor who arranged your scan. This will usually be your epilepsy specialist.
You might be offered an MRI scan when you are first being investigated for epilepsy, or if your seizures are difficult to control. The National Institute for Care and Health Excellence (NICE) recommends that you should have an MRI scan if you are in one of the following groups :
- You developed epilepsy before the age of two years
- You developed epilepsy when you were an adult
- You might have damage in your brain which could be causing the seizures
- You continue to have seizures despite taking epilepsy medicines
If you are being considered for an MRI scan, your doctor will ask whether you have a pacemaker, vagal nerve stimulator, or any other metal parts in your body. This is because The MRI scanner uses an extremely strong magnet, which can move, or damage metal objects, or affect the way they work. Metal objects can also affect the quality of the pictures from the scan. So, if you have metal in your body, an MRI scan is not suitable for you. However, if you can’t have an MRI scan, your epilepsy specialist, nurse or doctor may be able to arrange for you to have a different type of scan.
An MRI is not always useful for people who have:
- Generalised seizures(when seizures affect both halves of their brain) or
- Benign rolandic epilepsy
This is because these epilepsies are unlikely to be caused by damage to a single part of the brain. So, an MRI scan is unlikely to find anything that could help with a diagnosis.
An MRI needs to be arranged by a GP, epilepsy nurse or specialist. If you believe an MRI scan would help get the best treatment for your epilepsy, you could ask them about arranging an MRI for you.
NICE recommends that people with epilepsy who need an MRI scan should have one done within four weeks of the doctor requesting it.
If you would like to see this information with references, visit the Advice and Information references section of our website. If you are unable to access the internet, please contact our Epilepsy Freephone Helpline on 0808 800 5050.
Epilepsy Action would like to thank Dr Amanda Freeman, Consultant Paediatrician at Queen Alexandra Hospital, Portsmouth, UK for her contribution to this information.
Dr Amanda Freeman has no conflict of interest to declare.
This information has been produced under the terms of The Information Standard.
- Updated December 2014To be reviewed December 2017