Narrative review of epilepsy: getting the most out of your neuroimaging

Abstract

Neuroimaging represents an important step in the evaluation of pediatric epilepsy. The crucial role of brain imaging in the diagnosis, follow-up and presurgical assessment of patients with epilepsy is noted and has to be familiar to all neuroradiologists and trainees approaching pediatric brain imaging.Morphological qualitative imaging shows the majority of cerebral lesions/alterations underlying focal epilepsy and can highlight some features which are useful in the differential diagnosis of the different types of epilepsy. Recent advances in MRI acquisitions including diffusion-weighted imaging (DWI), postacquisition image processing techniques, and quantification of imaging data are increasing the accuracy of lesion detection during the last decades. Functional MRI (fMRI) can be really useful and helps to identify cortical eloquent areas that are essential for language, motor function, and memory, and diffusion tensor imaging (DTI) can reveal white matter tracts that are vital for these functions, thus reducing the risk of epilepsy surgery causing new morbidities. Also positron emission tomography (PET), single photon emission computed tomography (SPECT), simultaneous electroencephalogram (EEG) and fMRI, and electrical and magnetic source imaging can be used to assess the exact localization of epileptic foci and help in the design of intracranial EEG recording strategies. The main role of these "hybrid" techniques is to obtain quantitative and qualitative informations, a necessary step to evaluate and demonstrate the complex relationship between abnormal structural and functional data and to manage a "patient-tailored" surgical approach in epileptic patients.

Making the Invisible Visible: Advanced Neuroimaging Techniques in Focal Epilepsy

“…It is also important to differentiate epileptogenic lesions, particularly focal cortical dysplasia, from other findings, such as unspecific aging-related changes showing T2 hyperintensity. For that, we need to consider the main features of focal cortical dysplasia, including cortical thickening, blurring of gray–white matter junction, cortical or white matter T2 hyperintensity, and transmantle sign ( De Vito et al, 2021 ) ( Figures 1B , 3 ). To detect hippocampal sclerosis, which is the most common etiology of temporal lobe epilepsy ( Thom, 2014 ), attention should be paid to hippocampal atrophy and T2 hyperintensity, and thinning and blurring of the molecular layer ( Bernasconi et al, 2019 ; De Vito et al, 2021 ) ( Figure 4 ).…”

“…For that, we need to consider the main features of focal cortical dysplasia, including cortical thickening, blurring of gray–white matter junction, cortical or white matter T2 hyperintensity, and transmantle sign ( De Vito et al, 2021 ) ( Figures 1B , 3 ). To detect hippocampal sclerosis, which is the most common etiology of temporal lobe epilepsy ( Thom, 2014 ), attention should be paid to hippocampal atrophy and T2 hyperintensity, and thinning and blurring of the molecular layer ( Bernasconi et al, 2019 ; De Vito et al, 2021 ) ( Figure 4 ). As described, epileptogenic lesions are sometimes subtle, and 3D acquisition with reformats is important ( De Vito et al, 2021 ).…”

“…To detect hippocampal sclerosis, which is the most common etiology of temporal lobe epilepsy ( Thom, 2014 ), attention should be paid to hippocampal atrophy and T2 hyperintensity, and thinning and blurring of the molecular layer ( Bernasconi et al, 2019 ; De Vito et al, 2021 ) ( Figure 4 ). As described, epileptogenic lesions are sometimes subtle, and 3D acquisition with reformats is important ( De Vito et al, 2021 ). Therefore, we should be careful about motion artifact and quality control.…”

“…Regarding the magnetic field strength, 1.5- or 3-T MRI scanners are currently utilized in clinical practice. In principle, 3-T MRI provides a better signal-to-noise ratio and higher resolution of images, although we need to pay more careful attention to flow and motion artifact in 3-T scanners ( Martinez-Rios et al, 2016 ; De Vito et al, 2021 ). Indeed, some previous studies reported better identification of epileptogenic lesions by 3- than by 1.5-T MRI, and the use of 3-T MRI may improve the clinical decision making ( Knake et al, 2005 ; Zijlmans et al, 2009 ; Mellerio et al, 2014 ; Rubinger et al, 2016 ).…”

Identification of epidermal growth factor receptor as an immune-related biomarker in epilepsy using multi-transcriptome data

“…During the last decades, due to the increasing use of MRI in epilepsy, cortical malformations have been “reconsidered” as one of the most frequent etiologies of focal epileptic seizures in both pediatric and young adults population ( 1 ). Children with lesional epilepsy are more likely to have focal cortical dysplasia (FCD), which is a prominent cause of refractory epilepsy ( 2 - 4 ).…”