Magnetic resonance imaging (MRI) is one of the key diagnostic tools used to visualize changes in the brain associated with seizures and epilepsy.

Epilepsy is characterized by recurrent seizures without another known and reversible cause like:

  • electrolyte imbalances
  • brain infection
  • medication side effects

Epilepsy affects about 1.2% of the U.S. population.

Doctors use many tests to diagnose epilepsy, including magnetic resonance imaging (MRI). You may have an MRI test to:

  • look for changes in your brain associated with epilepsy
  • determine your type of epilepsy
  • determine whether you may benefit from surgery
  • decide the best type of surgery

In this article, we take a deeper look at how MRIs are used to diagnose and manage epilepsy.

An MRI cannot directly show if you have epilepsy, but it can potentially identify atypical signs in your brain associated with seizures, such as tumors or scarring.

Additionally, an MRI can help doctors determine whether you may benefit from surgery and which type of surgery might benefit you most.

For example, temporal lobe epilepsy with hippocampal sclerosis is one of the most common focal epilepsies and often doesn’t respond to medications. Surgery is successful in treating this type of epilepsy in about 80% of cases.

MRIs are widely used to help diagnose epilepsy.

MRI techniques include:

  • Volumetric MRI: The volumes of certain sections of your brain, like the hippocampus, are compared with what would be expected.
  • MRI fingerprinting: This new technique allows the measurement of multiple tissue properties with one scan. Research from 2021 shows it may improve the detection of abnormalities in the medial and temporal areas of the brain.
  • Diffused weighted MRI: This technique measures the motion of water molecules within the cells in your brain to create an image.
  • Functional MRI: A functional MRI measures changes in blood flow in your brain. It’s traditionally been used to guide surgical decisions.
  • MR spectroscopy imaging: MR spectroscopy allows doctors to see biochemical changes in your brain, particularly those related to tumors.

The International League Against Epilepsy Neuroimaging Task Force published updated guidelines in 2019. They recommend that a series of MRIs called the HARNESS-MRI should be performed:

  • soon after the first seizure, particularly in young children
  • for people with atypical symptoms like cognitive decline
  • again if previous images are of suboptimal quality, particularly in people with drug-resistant epilepsy

In addition, the United Kingdom’s NICE guidelines recommend:

  • offering an MRI scan to people diagnosed with epilepsy unless they have genetic generalized epilepsy or benign Rolandic epilepsy
  • considering repeated scanning for people with epilepsy if:
    • the original scan was suboptimal
    • new symptoms develop
    • genetic generalized epilepsy or benign Rolandic epilepsy don’t respond to first line treatment
    • surgery is being considered

Atypical signs in imaging are seen in nearly 50% of people with epilepsy.

An MRI may reveal:

  • brain tumors
  • abnormal bundles of blood vessels (arteriovenous malformations)
  • the loss of brain tissue from your hippocampus (hippocampal sclerosis)
  • scarring in your brain (gliosis)
  • atypical development of the brain before you’re born (polymicrogyria)
  • an area of abnormal neurons (cortical dysplasia)

MRIs are safe and painless. They don’t expose your body to any radiation.

There is usually very little specific preparation for a head MRI. But before your procedure, it’s important to tell your doctor and technicians if you:

  • feel claustrophobic in tight spaces
  • have any metal implants like brain aneurysm clips or a pacemaker
  • have been injured in the past with metal shrapnel

Before your procedure, you must remove any jewelry and anything else you’re wearing that contains metal.

The procedure you receive depends on the type of MRI but generally looks something like this:

  1. Children and people who feel anxious may need sedation either taken orally or through an IV before their MRI to help them keep still.
  2. You will lie on a bed that slides into the tube-shaped MRI machine. You may have a coil placed on your head.
  3. Your technician will turn on the MRI scanner, which will make a series of loud sounds while it’s taking images.
  4. You will likely be able to go home once it’s confirmed that the pictures came out clear.

The HARNESS-MRI protocol comprises three scans that each last for 7–10 minutes.

Here are some frequently asked questions people have about imaging for epilepsy.

Is a CT scan or MRI better for epilepsy?

MRIs are preferred over CT scans for evaluating epilepsy. MRIs provide more detailed images.

CT scans might be performed when an MRI isn’t available.

What other brain scans are available for epilepsy?

Other types of brain scans used to investigate epilepsy include:

Electroencephalogram (EEG) is also among the most common tests used to diagnose epilepsy. It involves measuring brain activity with electrodes on your scalp.

EEGs do not produce a picture of the brain but rather a tracing of brain activity. It can detect ongoing seizures, and sometimes it can detect atypical electrical activity in a region of the brain where seizures start — even when a seizure isn’t happening.

An EEG is used along with imaging tests, like MRIs, for determining which epilepsy medication is likely to be helpful and for planning epilepsy surgery.

What is the difference between MRI and epilepsy protocol MRI?

A standard MRI provides an image of the structures of your brain. An epilepsy protocol MRI is a group of different types of MRI images taken to look for structural abnormalities in your brain that might lead to a seizure.

MRI scans are commonly used to investigate the underlying cause of seizures. They can potentially reveal changes to your brain, such as tumors, scarring, or loss of brain mass.

An MRI can also help doctors determine if you may benefit from surgery and which type of surgery may be best.

You do not usually need to prepare much for an MRI. Usually, the imaging itself takes less than 30 minutes.