Epilepsy Program

Neuroimaging Tests

MRI is the most important brain imaging test for epilepsy. It uses magnetic pulses to map the structure of the brain, providing a very detailed image. No radiation is given to the patient in an MRI. This test will not show epileptic activity, but may demonstrate a structural abnormality in brain, of a type likely to give rise to seizures. 

MRIs can show new and old strokes, bleeding in or around the brain, inflammation from meningitis, abnormal blood vessels (arteriovenous malformations, cavernous malformations, aneurysms), sites of head trauma, brain infections or their aftermath, benign or malignant tumors, multiple sclerosis, birth malformations of brain (called dysplasias), and several other types of a structural problem.    A condition of special interest for epilepsy is called "mesial temporal sclerosis."

This represents a scarring of the inner temporal lobe (hippocampus) of a type likely to occur with repeated seizures from the temporal lobe. It is a marker for a likely place where seizures originate.   Not all MRIs are alike, having different degrees of detail, different techniques and different methods of highlighting certain desired features. In addition, MRIs (or the underlying conditions seen in them) can change over time. Therefore, MRIs sometimes bear repeating, even if a prior MRI was normal.  

CT (computerized tomography)

Scans utilize radiation to image the brain. CT is an older technique than is MRI. In general, CT scans are quicker and cheaper to obtain, but do not have as much detail useful for evaluating epilepsy as does MRI.  

PET (positron emission tomography)

Uses trace radioactive compounds (usually glucose) to map the metabolic energy consumption of brain.  Energy consumption is abnormal between seizures in about 60% of people with uncontrolled complex partial seizures.  PET scans are not used for epilepsy diagnosis, but may help with localization of the seizure onset region in patients being considered for epilepsy surgery.  


Is a neuroimaging study designed to highlight the blood vessels of brain.  It is used mostly for stroke diagnosis, but may be helpful in showing malformed blood vessels that can cause seizures.   

Magnetic Resonance Angiogram (MRA)

Uses magnetic pulses to noninvasively image blood flow through arteries and veins of the brain.  A dye angiogram is done by injecting dye into the arterial circulation to highlight the blood flow. It is more detailed and accurate than is an MRA, but dye angiography entails more risk.

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