MRI in Epilepsy: The Epilepsy Protocol & Finding the Focus
In focal epilepsy the question is where the seizure focus is, and a routine brain MRI often isn’t enough to answer it.
Why a dedicated protocol
The common epileptogenic lesions are small and subtle, so epilepsy centres use a dedicated high-resolution protocol rather than a standard brain scan: thin slices, high-resolution 3D T1, and oblique-coronal sequences angled to the long axis of the hippocampus.
What it looks for
- Hippocampal sclerosis: the commonest cause of temporal-lobe epilepsy; hippocampal volume loss and increased T2/FLAIR signal, best seen on angled coronal images.
- Focal cortical dysplasia: subtle cortical thickening, blurred grey–white junction, and the “transmantle” sign; easily missed without high resolution.
- Other lesions: low-grade tumours, cavernomas, and developmental anomalies.
Role in surgery
Identifying and localising a lesion strongly influences whether epilepsy surgery is offered and improves seizure-freedom rates. MRI is combined with EEG, and sometimes PET, functional MRI (language/motor mapping) and other tools in the presurgical workup. Higher field strength (3T, and 7T in research) increases lesion detection.
Sources
- Bernasconi A et al. Recommendations for the use of structural MRI in the care of patients with epilepsy (ILAE Neuroimaging Task Force). Epilepsia 2019;60:1054–68.
Educational summary for clinicians; presurgical evaluation is specialist. Not medical advice.