Epilepsy imaging: New challenges on the diagnosis

Abstract

Imaging is pivotal in the evaluation and management of patients with epilepsies. High-resolution structural neuroimaging with magnetic resonance imaging (MRI) plays a vital role in defining the etiology, epilepsy syndrome, and prognosis of seizure disorders. The type of lesion identified by MRI is associated with different probabilities of pharmacoresistance. It is essential that structural MRIs are optimally acquired, including 3D T1-weighted and FLAIR sequences, and carefully reviewed by trained experts within the context of all available clinical and EEG data. Multiplanar reformatting of high-resolution MRI and correlation with functional multimodal imaging improves the detection of subtle lesions. Detection of a lesion on a previous negative MRI has a substantial impact on determining the etiology of epilepsy, reducing the need for invasive investigations, and planning surgical treatment in patients with pharmacoresistant seizures and for the postoperative outcome. The high diagnostic yield of MRI to identify the common pathological findings in individuals with focal seizures, including mesial temporal sclerosis, vascular anomalies, low-grade glial neoplasms, and malformations of cortical development (MCD), has been well established. Quantitative postprocessing may help to complement the evaluation of subtle MCDs. Positron emission tomography (PET) is the most performed interictal functional neuroimaging technique that may reveal a focal hypometabolic region concordant with seizure onset. Single-photon emission computed tomography (SPECT) studies may assist the performance of ictal neuroimaging in patients with pharmacoresistant focal epilepsy. Emerging functional imaging modalities, such as functional MRI (fMRI), and EEG-fMRI, may help to reduce the need for invasive investigations and predict prognosis.