Imaging in Seizure


Associate Professor of Radiology Tehran University of Medical Science, Tehran .Iran



Imaging has an important role in the evaluation and management of patients with seizure disorders. Structural neuroimaging with magnetic resonance imaging (MRI) assist determination of etiology of focal epilepsy and demonstrates the anatomical changes associated with seizure activity.
Mesial temporal sclerosis, vascular anomalies, low-grade glial neoplasms and malformations of cortical development has been demonstrated to be the major causes of seizure in individuals with focal seizures which could be easily diagnosed by MRI. Correct identification and localization of epileptogenic foci is a crucial preoperative step in intractable seizure, some of these patients have no abnormality on routine magnetic resonance imaging (MRI) and advanced imaging techniques, therefore, can be helpful to identify the area of concern. Positron emission tomography (PET), functional MRI, and diffusion tensor imaging– tractography are new methods.PET is the most commonly performed interictal functional neuroimaging technique that may reveal a focal hypometabolic region concordant with seizure onset.
An epilepsy-tailored MRI technique should be performed to detect subtle lesions. This includes three-dimensional (3D) T1- weighted image, gradient echo and 3D fluid- attenuated inversion recovery (FLAIR) images with isotropic voxels, Coronal and axial high- resolution T2-weighted images with 2–3 mm slice thickness. These are useful for detection of FCD and MTS.A 3D susceptibility-weighted imaging (SWI) sequence is required for microbleeds and faint calcification. Moreover, coronal T1 inversion recovery is used for better delineation of the gray–white matter interface, 3D T2, diffusion weighted imaging (DWI) for possible ischemic lesion, and post-contrast scan in case of inflammation or tumors. The use of 3T MRI is favored over regular 1.5T MRI machines and the surgical success depends on the use of advanced brain imaging techniques to identify the epileptic focus.