Brain Imaging Tests for Epilepsy

Reviewed by: HU Medical Review Board | Last reviewed: November 2021

Epilepsy is a neurological (brain) disease that causes people to have seizures. It is a type of seizure disorder in which clusters of neurons (nerve cells in the brain) behave abnormally. Neurons normally create tiny electrical signals in a regular rhythm. These brain waves tell other parts of the brain and body what to do.1,2

However, not all seizures are caused by epilepsy. Seizures may be caused by a host of other health conditions. Brain imaging tests help doctors decide if something physical in the brain is causing seizures. This includes infection, tumor, head injury, stroke, or a vein cluster in the brain.1,2

The most common imaging tests ordered for epilepsy are magnetic resonance imaging (MRI) and computed tomography (CT scan). Both tests take pictures of the brain. These pictures help your doctor know if seizures are caused by changes to the structure of the brain.1,2

Magnetic resonance imaging (MRI)

MRI is a noninvasive test using a magnetic field and radio waves to create images of the body. MRIs can be used to get detailed images of the body, including anatomy, tissue damage, reduced blood flow, and tumors.

If your doctor suspects epilepsy, a special brain MRI called a seizure protocol MRI may be done. This MRI takes more detailed pictures of parts of the brain where small structural changes most often cause seizures. Sometimes dye is injected into the veins to highlight certain areas of the brain. An MRI of the brain usually takes 30 to 40 minutes to complete.1-3

An MRI of the head and neck area may help rule out lesions (tumors) in the brain that can cause symptoms similar to epilepsy.

Computerized tomography (CT scan)

A CT scan is a more detailed type of X-ray. The test is performed inside a doughnut-shaped machine. It can be performed with or without contrast iodine dye, depending on the reason the study is being obtained. This dye is used to highlight certain areas of the brain, especially areas where there may be inflammation. A CT scan of the brain usually takes a few minutes to complete.1-3

Less common brain imaging tests

Other brain imaging tests may be ordered if an MRI or CT scan does not give doctors enough information. MRIs and CT scans are pictures of the structure of the brain. The following tests are used when doctors want to see how the brain is working:3

  • Single-photon emission computed tomography (SPECT) – Maps blood flow through the brain
  • Positron emission tomography (PET) – Tracks how much sugar (glucose) or oxygen is used by the brain
  • Magnetoencephalography (MEG)
  • – A more sensitive test than electroencephalogram (EEG) that measures electrical patterns in the brain

  • Magnetic resonance spectroscopy (MRS) – Helps track metabolism in the brain of certain elements like phosphorus
  • Ultrasound – Used to look for fluid or blood in the brain

These tests are most often used before epilepsy surgery or during research.

Other tests for epilepsy

To diagnose epilepsy, your doctor will also order other tests and conduct a physical exam. The other tests may include:1,2

  • Urinalysis
  • EEG
  • Blood tests
  • Spinal tap (lumbar puncture)Hospital monitoring
  • Genetic testing

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