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Brain scans for epilepsy

A brain scan may help to find the cause of your seizures. The two common types of brain scan are Magnetic Resonance Imaging (MRI) and Computerised Axial Tomography (CT or CAT).

Doctor looking a brain scansThe scan produces pictures of the brain which might show a physical cause for epilepsy, such as a scar on the brain. But for many people a brain scan does not show a cause for their seizures, and even if no physical cause is seen, the person may still have epilepsy.

Magnetic Resonance Imaging (MRI) scan

An MRI scan looks at the structure of the brain and may help to find the cause of your epilepsy. During the scan, detailed pictures are produced using strong magnetic fields. Because of the magnetic fields, metal objects in or near the machine can affect, or be affected by, the machine.

Before having an MRI scan you will need to remove any metal objects such as jewellery, hearing aids, coins or keys. If you have a heart pacemaker or any surgical implant that contains metal you may not be able to have an MRI scan.

The scanner makes a loud knocking noise, so before it starts you will be given earplugs to wear. You will also be given a buzzer to hold so you can let the technician know if you are uncomfortable or feeling unwell during the scan.

The technician is usually on the other side of a window in another room during the scan. There is an intercom so you can talk to them and a mirror so you can see them. You may be able to have someone in the room with you during the scan.

Having an MRI scan to help diagnose epilepsy usually takes about 30 minutes. During the scan you will lie on a platform which slides into the scanner (a bit like going into a tunnel).

It is important to lie still during the scan so that the machine can take clear pictures of your brain. An MRI scan is usually a series of short scans with breaks in between, rather than one long scan. Between each scan the technician might use the intercom to check that you are ok.

Computerised axial tomography (CT or CAT scan)

Some people may have a CT scan if they are not able to have an MRI scan. This might be because they have a heart pacemaker, if they might need to have an anaesthetic to have an MRI or if information about what might be causing their seizures is needed quickly.

CT scans use X-rays to take images of the brain. (CT scans are not suitable if you are pregnant because the X-rays could affect an unborn baby). 

Images from a CT scan are less detailed than those from MRI scans. During a CT scan you lie on a couch which slides into the scanner. Unlike MRI scanners, CT scanners do not make a loud noise.

Someone pointing to a MRI scan with a pencil

A closer look at MRI

Get a closer look at MRI including further information on atoms, protons and spectroscopy.


Taken from our diagnosis leaflet. Order this leaflet from our online shop as part of our 'first five free offer' or download the pdf using the link below.