Black Line Sign in Focal Cortical Dysplasia IIB: A 7T MRI and Electroclinicopathologic Study

Clinical 7 Tesla magnetic resonance imaging: Impact and patient value in neurological disorders

Magnetic resonance imaging (MRI) is a cornerstone of non-invasive diagnostics and treatment monitoring, particularly for diseases of the central nervous system. Although 1.5- and 3 Tesla (T) field strengths remain the clinical standard, the advent of 7 T MRI represents a transformative step forward, offering superior spatial resolution, contrast, and sensitivity for visualizing neuroanatomy, metabolism, and function. Recent innovations, including parallel transmission and deep learning-based reconstruction, have resolved many prior technical challenges of 7 T MRI, enabling its routine clinical use. This review examines the diagnostic impact, patient value, and practical considerations of 7 T MRI, emphasizing its role in facilitating earlier diagnoses and improving care in conditions, such as amyotrophic lateral sclerosis (ALS), epilepsy, multiple sclerosis (MS), dementia, parkinsonism, tumors, and vascular diseases. Based on insights from over 1200 clinical scans with a second-generation 7 T system, the review highlights disease-specific biomarkers such as the motor band sign in ALS and the new diagnostic markers in MS, the central vein sign, and paramagnetic rim lesions. The unparalleled ability of 7 T MRI to study neurological diseases ex vivo at ultra-high resolution is also explored, offering new opportunities to understand pathophysiology and identify novel treatment targets. Additionally, the review provides a clinical perspective on patient handling and safety considerations, addressing challenges and practicalities associated with clinical 7 T MRI. By bridging research and clinical practice, 7 T MRI has the potential to redefine neuroimaging and advance the understanding and management of complex neurological disorders.

Focal cortical dysplasia type II: review of neuropathological manifestations and pathogenetic mechanisms

Focal cortical dysplasia (FCD) is an important cause of intractable epilepsy, with FCD type II (FCD II) being the most common subtype. FCD II is characterized by cortical dyslamination accompanied by dysmorphic neurons (DNs). Identifying the molecular alterations and targetable biomarkers is pivotal for developing therapies. Here, we provide a detailed description of the neuropathological manifestations of FCD II, including morphological alterations and immunophenotypic profiles, indicating that abnormal cells exhibit a diverse spectrum of mixed differentiation states. Furthermore, we summarize current research on the pathogenetic mechanisms, indicating that gene mutations, epigenetic alterations, cortical developmental protein disturbances, inflammatory processes, and extrinsic damages may lead to abnormal neuronal proliferation and migration, thereby contributing to the emergence and progression of FCD II. These findings not only enhance our understanding of the pathogenesis of FCD II but also offer new directions for clinical diagnosis and treatment. Future research should further explore the interactions among these factors and employ multidisciplinary approaches to advance our understanding of FCD II.

Development and prospective clinical validation of a convolutional neural network for automated detection and segmentation of focal cortical dysplasias

PURPOSE

Focal cortical dysplasias (FCDs) are a leading cause of drug-resistant epilepsy. Early detection and resection of FCDs have favorable prognostic implications for postoperative seizure freedom. Despite advancements in imaging methods, FCD detection remains challenging. House et al. (2021) introduced a convolutional neural network (CNN) for automated FCD detection and segmentation, achieving a sensitivity of 77.8%. However, its clinical applicability was limited due to a low specificity of 5.5%. The objective of this study was to improve the CNN's performance through data-driven training and algorithm optimization, followed by a prospective validation on daily-routine MRIs.

MATERIAL AND METHODS

A dataset of 300 3 T MRIs from daily clinical practice, including 3D T1 and FLAIR sequences, was prospectively compiled. The MRIs were visually evaluated by two neuroradiologists and underwent morphometric assessment by two epileptologists. The dataset included 30 FCD cases (11 female, mean age: 28.1 ± 10.1 years) and a control group of 150 normal cases (97 female, mean age: 32.8 ± 14.9 years), along with 120 non-FCD pathological cases (64 female, mean age: 38.4 ± 18.4 years). The dataset was divided into three subsets, each analyzed by the CNN. Subsequently, the CNN underwent a two-phase-training process, incorporating subset MRIs and expert-labeled FCD maps. This training employed both classical and continual learning techniques. The CNN's performance was validated by comparing the baseline model with the trained models at two training levels.

RESULTS

In prospective validation, the best model trained using continual learning achieved a sensitivity of 90.0%, specificity of 70.0%, and accuracy of 72.0%, with an average of 0.41 false positive clusters detected per MRI. For FCD segmentation, an average Dice coefficient of 0.56 was attained. The model's performance improved in each training phase while maintaining a high level of sensitivity. Continual learning outperformed classical learning in this regard.

CONCLUSIONS

Our study presents a promising CNN for FCD detection and segmentation, exhibiting both high sensitivity and specificity. Furthermore, the model demonstrates continuous improvement with the inclusion of more clinical MRI data. We consider our CNN a valuable tool for automated, examiner-independent FCD detection in daily clinical practice, potentially addressing the underutilization of epilepsy surgery in drug-resistant focal epilepsy and thereby improving patient outcomes.

Drug-resistant epilepsy: Definition, pathophysiology, and management

There are currently >51 million people with epilepsy (PWE) in the world and every year >4.9 million people develop new-onset epilepsy. The cornerstone of treatment in PWE is drug therapy with antiseizure medications (ASMs). However, about one-third of PWE do not achieve seizure control and do not respond well to drug therapy despite the use of appropriate ASMs [drug-resistant epilepsy (DRE)]. The aims of the current narrative review are to discuss the definition of DRE, explain the biological underpinnings and clinical biomarkers of this condition, and finally to suggest practical management strategies to tackle this issue appropriately, in a concise manner.

Pearls & Oy-sters: Harnessing New Diagnostic and Therapeutic Approaches to Treat a Patient With Genetic Drug-Resistant Focal Epilepsy

Focal cortical dysplasia (FCD) is a congenital developmental malformation and is one of the leading causes of drug-resistant focal epilepsy (DRFE). Although focal epilepsies traditionally have been regarded as acquired disorders, increasing evidence suggests a substantial genetic contribution to the pathogenesis of focal structural epilepsies, including FCDs. Variations in the Dishevelled, Egl-10, and domain-containing protein 5 (DEPDC5) have recently emerged as a causative gene mutation in familial focal epilepsies associated with FCD type 2a, including bottom-of-sulcus dysplasia (BOSD). We present the case of a 20-year-old man with DRFE, positive for DEPDC5 c.1555C>T (p.GIn519*) heterozygous pathogenic variant. Initial 3T brain MRI was unrevealing, but subsequent 7T MRI including 7T edge-enhancing gradient echo revealed a left superior frontal sulcus BOSD concordant with the electroclinical data. The patient underwent treatment with MR-guided laser interstitial thermal ablation of the left frontal BOSD without intracranial EEG monitoring (skipped candidate), resulting in a seizure-free outcome of 9 months since the last follow-up. Our case highlights the real-world application of summative information obtained through advancements in epilepsy genetic testing, minimally invasive surgeries, and ultra-high field MRI, allowing us to provide a safe and effective treatment for a patient with a genetic DRFE.

Focal cortical dysplasia: a practical guide for neurologists

Focal cortical dysplasia (FCD) is a malformation of cortical development characterised by disruption of cortical cytoarchitecture. Classification of FCDs subtypes has initially been based on correlation of the histopathology with relevant clinical, electroencephalographic and neuroimaging features. A recently proposed classification update recommends a multilayered, genotype-phenotype approach, integrating findings from histopathology, genetic analysis of resected tissue and presurgical MRI. FCDs are caused either by single somatic activating mutations in MTOR pathway genes or by double-hit inactivating mutations with a constitutional and a somatic loss-of-function mutation in repressors of the signalling pathway. Mild malformation with oligodendroglial hyperplasia in epilepsy is caused by somatic pathogenic SLC35A2 mutations. FCDs most often present with drug-resistant focal epilepsy or epileptic encephalopathy. Most patients respond to surgical treatment. The use of mechanistic target of rapamycin inhibitors may complement the surgical approach. Treatment approaches and outcomes have improved with advances in neuroimaging, neurophysiology and genetics, although predictors of treatment response have only been determined in part.