This page covers the types of scans most commonly used, as well as referral and follow-up procedures.
Brain scans play an important role in diagnosing the specific causes of epilepsy in children and young people.
Types of neuroimaging (brain scans)
Neuroimaging – a brain scan – gives a detailed picture of the brain’s structure.
Brain scans can help to identify an area of the brain that has not developed properly or an area of brain tissue damaged through a lack of oxygen or a bleed.
There are different types of brain scans. The types commonly used in children and young people diagnosed with epilepsy are:
- Magnetic resonance imaging (MRI ) scans
- 3T MRI – has a stronger magnet and makes better images of organs and soft tissue than other types of MRI
- Functional magnetic resonance imaging (fMRI) scans
- Computerised tomography (CT) scans
Using magnetic fields, not X-rays, a magnetic resonance imaging (MRI) scan gives a sharp and detailed image of the brain’s structure.
An MRI scan with functional imaging (fMRI) provides images of the brain’s structures, abnormalities in the brain and blood flow in a specific area of the brain.
When we think, speak, move or use our senses, there’s an increased blood flow to the area of the brain that we’re using.
This makes an fMRI scan extremely useful for mapping which parts of the brain control different bodily functions and seeing where seizures start.
A computerised tomography (CT) scan records very detailed cross-sectioned images of the brain onto a computer, though not as sharp or detailed as an MRI scan.
A CT scan is safe and painless.
CT scans show both bone and soft issues, including the various parts of the brain.
A CT scan may reveal an obvious structural abnormality or damage to the brain.
CT scans are not suitable for people with established epilepsy who visit an emergency department after a typical seizure, unless there are other concerns.
First scan
The first scan children and young people and will be offered is an MRI scan. Unless their epilepsy has a genetic cause or they have self-limited epilepsy with centrotemporal spikes (SeLECTS).
The MRI should:
- Take place within six weeks of referral
- Follow agreed guidelines (MRI epilepsy protocol) to make sure it’s of the best quality possible to aid accurate diagnosis of the cause of epilepsy
Because MRI scans involve having to lie still for some time in an enclosed and noisy space, they can be unsettling for children.
So, some children may need sedation or anaesthesia, depending on their age, before an MRI scan.
Sometimes, as part of an MRI scan, children will be given an injection of dye into the bloodstream, through the hand or foot, to highlight the blood vessels in the brain. This is called ‘MRI with contrast’.
If an MRI scan is not suitable for a child or young person diagnosed with epilepsy, they’ll be offered a CT scan.
Sometimes, as part of a CT scan, children will be given an injection of dye into the bloodstream, through the hand or foot, to highlight the blood vessels in the brain.
With both MRI and CT scans, the risks and benefits should be discussed first with the child, young person or adult with epilepsy, and families and carers, as appropriate – especially if a general anaesthetic or sedation is needed for the scan.
If the seizures continue despite treatment, and there’s still no clear diagnosis, it’s possible the MRI scans will be sent for further review by a hospital specialist.
Repeat scans
A repeat scan may be necessary if:
- The quality of the first scan wasn’t clear enough to get an accurate diagnosis
- The child or young person’s epilepsy has developed new features
- Their epilepsy has a genetic cause or they have self-limited epilepsy with centrotemporal spikes (SeLECTS), and have not responded to initial treatment
- They’re being considered for surgery
Other types of scans are available
With a single photon emission computed tomography (SPECT) scan of the brain, a computer gathers together the images and shows them in cross-sections.
These images can be added together to form a 3D image.
When there’s brain injury, there’s reduced blood flow to the specific part of the brain that’s been damaged.
During a SPECT scan, dye is injected into the bloodstream, allowing the scan to trace and identify areas of reduced blood flow in the brain.
If a SPECT scan is performed during a seizure, it will show where in the brain the seizure started.
Find out more about epileptic seizures.
Positive emission tomography (PET) scans are more precise than SPECT scans.
They show how tissues in the brain are functioning and reveal structural abnormalities that will not show up on an MRI scan.
PET scans are, however, not widely available. They are, though, sometimes used to help plan operations, eg brain surgery for epilepsy.
Find out more about PET scans.
