Making the Invisible Visible: Advanced Neuroimaging Techniques in Focal Epilepsy

Abstract

It has been a clinically important, long-standing challenge to accurately localize epileptogenic focus in drug-resistant focal epilepsy because more intensive intervention to the detected focus, including resection neurosurgery, can provide significant seizure reduction. In addition to neurophysiological examinations, neuroimaging plays a crucial role in the detection of focus by providing morphological and neuroanatomical information. On the other hand, epileptogenic lesions in the brain may sometimes show only subtle or even invisible abnormalities on conventional MRI sequences, and thus, efforts have been made for better visualization and improved detection of the focus lesions. Recent advance in neuroimaging has been attracting attention because of the potentials to better visualize the epileptogenic lesions as well as provide novel information about the pathophysiology of epilepsy. While the progress of newer neuroimaging techniques, including the non-Gaussian diffusion model and arterial spin labeling, could non-invasively detect decreased neurite parameters or hypoperfusion within the focus lesions, advances in analytic technology may also provide usefulness for both focus detection and understanding of epilepsy. There has been an increasing number of clinical and experimental applications of machine learning and network analysis in the field of epilepsy. This review article will shed light on recent advances in neuroimaging for focal epilepsy, including both technical progress of images and newer analytical methodologies and discuss about the potential usefulness in clinical practice.

Diagnostic and therapeutic approaches in refractory insular epilepsy

“…4.1.2 | Diffusion-Weighted MRI Diffusion-weighted MRI helps to lateralize and to localize the EZ. 22 A diffusion-weighted MRI study in extra-temporal lobe epilepsy (ETLE) demonstrated the usefulness of diffusion tensor imaging (DTI) to localize the EZ when coupled with positron emission tomography (PET) using 18 Fluor-labeled fluorodeoxyglucose ( 18 F-FDG-PET). Nevertheless, no significant results were detected in the single case of insular epilepsy.…”

“…24 4.1.4 | Perfusion MRI Arterial spin labeling (ASL) can assess brain perfusion and detect blood flow changes around the EZ during the interictal period. 22 Nevertheless, there is no detailed description of ASL application in insular epilepsy. 4.1.5 | Functional MRI Functional MRI combined with electroencephalography (EEG-fMRI) could help to characterize the changes in blood oxygen level-dependent (BOLD) signal associated with interictal epileptiform discharges (IEDs) recorded during fMRI data acquisition.…”

Emerging Trends in the Management of Cryptogenic Epilepsy

“…The previous so-called 'cryptogenic epilepsy' cases by 1.5T MRI system turned out to be lesional cases after being rescanned by 3T MRI system with multichannel phased-array coils (Figure 2). Some centres are now using a 7T MRI system to confirm the suspicion in 3T MRI and locate any subtle lesions [16][17][18]. Apart from the increased signal-to-noise ratio, postprocessing of MRI images by the application of voxel-based morphometric analysis using morphometric analysis program (MAP) is another emerging direction to detect those subtle epileptogenic foci [13,19,20].…”

Cytokine profile in the peripheral blood and the brain in patients with focal drug-resistant epilepsy

“…Для визуализации использовали систему Streptavidin-Peroxidase Polymer, Ultrasensitive и хромоген DAB (Sigma-Aldrich, США), срезы докрашивали гематоксилином Джилла, заключали в синтетическую заливочную среду Bio Mount HM (Bio-Optica, Италия). Оценка результата реакции проводилась путем подсчета денситометрической плотности окрашенных клеток относительно фоновых областей в 10 полях зрения в программе PhotoM 1.21 2 .…”

“…Доля пациентов с эпилепсией составляет 1% от общего числа всех заболеваний [1]. Несмотря на успехи фармакологии, у более чем 30% пациентов заболевание прогрессирует до формирования лекарственно-устойчивой эпилепсии и нуждается в хирургическом лечении [2]. Развитие резистентности к противоэпилептическим средствам может быть связано с нарушениями проницаемости гематоэнцефалического барьера (ГЭБ).…”