Imaging phenotype correlation with molecular and molecular pathway defects in malformations of cortical development

Focally Enlarged Perivascular Spaces in Pediatric and Adolescent Patients with Polymicrogyria-an MRI Study

PURPOSE

Polymicrogyria (PMG) is a cortical malformation frequently associated with epilepsy. Our aim was to investigate the frequency and conspicuity of enlarged perivascular spaces (EPVS) underneath dysplastic cortex as a potentially underrecognized feature of PMG in pediatric and adolescent patients undergoing clinical magnetic resonance imaging (MRI).

METHODS

We analyzed data from 28 pediatric and adolescent patients with PMG and a matched control group, ranging in age from 2 days to 21 years, who underwent MRI at 1.5T or 3T. T2-weighted MR images were examined for the presence of EPVS underneath the dysplastic cortex. The quantity of EPVS was graded from 0 to 4 (0: none, 1: < 10, 2: 11-20, 3: 21-40, 4: > 40 EPVS). We then compared the presence and quantity of EPVS to the matched controls in terms of total EPVS scores, and EPVS scores underneath the dysplastsic cortex depending on the age groups, the localization of PMG, and the MRI field strength.

RESULTS

In 23/28 (82%) PMG patients, EPVS spatially related to the dysplastic cortex were identified. EPVS scores were significantly higher in PMG patients compared to controls, independent from age or PMG location. No significant differences were observed in EPVS scores in patients examined at 1.5T compared to those examined at 3T.

CONCLUSION

EPVS underneath the dysplastic cortex were identified in 82% of patients. EPVS may serve as an important clue for PMG and a marker for cortical malformation.

Relationship between prenatal ultrasound signs and genetic abnormalities for fetal malformations of cortical development

To explore the relationship between ultrasound signs of suspected fetal malformation of cortical development (MCD) and genetic MCD.The retrospective study involved fetuses with one of the following 10 neurosonography (NSG) signs: (A) abnormal development of the Sylvian fissure; (B) delayed achievement of cortical milestones; (C) premature or aberrant appearance of sulcation; (D) irregular border of the ventricular wall or irregular shape of the ventricle; (E) abnormal shape or orientation of the sulci; (F) hemispheric asymmetry; (G) non-continuous cerebral cortex; (H) intraparenchymal echogenic nodules; (I) persistent ganglionic eminence (GE) or GE cavitation; (J) abnormal cortical lamination.95 fetuses were included in the study. Chromosomal microarray (CMA) combined with exome sequencing (ES) was available in 40 fetuses, CMA was abnormal in nine and ES in 22. Sign C (7/7, 100%), sign H (2/2, 100%), sign A (18/19, 94.7%), and sign B (12/13, 92.3%) were the signs leading to the highest probability of genetic MCD. The incidence of genetic MCD for sign E, sign I, and sign D was 66.7-73.7%. Only one or none of the fetuses with sign J, sign F, or sign G underwent CMA+ES. The signs in the fetuses with FGFR3, CCND2, FLNA, or TSC2 mutations had the expected features. The other fetuses with different gene mutations showed several non-specific NSG signs.Several reliable signs for genetic MCD can be detected by NSG, and the probability varies with different signs. Most signs are not associated with a specific gene. Therefore, CMA combined with ES is preferred.

Malformations of Cortical Development: Updated Imaging Review

Malformations of cortical development (MCD) are structural anomalies that disrupt the normal process of cortical development. Patients with these anomalies frequently present with seizures, developmental delay, neurologic deficits, and cognitive impairment, resulting in a wide spectrum of neurologic outcomes. The severity and type of malformation, in addition to the genetic pathways of brain development involved, contribute to the observed variability. While neuroimaging plays a central role in identifying congenital anomalies in vivo, the precise definition and classification of cortical developmental defects have undergone significant transformations in recent years due to advances in molecular and genetic knowledge. The authors provide a concise overview of embryologic brain development, recently standardized nomenclature, and the categorization system for abnormalities in cortical development, offering valuable insights into the interpretation of their neuroradiologic patterns. ©RSNA, 2024 Supplemental material is available for this article. The slide presentation from the RSNA Annual Meeting is available for this article.

The molecular genetics of PI3K/PTEN/AKT/mTOR pathway in the malformations of cortical development

Malformations of cortical development (MCD) are a group of developmental disorders characterized by abnormal cortical structures caused by genetic or harmful environmental factors. Many kinds of MCD are caused by genetic variation. MCD is the common cause of intellectual disability and intractable epilepsy. With rapid advances in imaging and sequencing technologies, the diagnostic rate of MCD has been increasing, and many potential genes causing MCD have been successively identified. However, the high genetic heterogeneity of MCD makes it challenging to understand the molecular pathogenesis of MCD and to identify effective targeted drugs. Thus, in this review, we outline important events of cortical development. Then we illustrate the progress of molecular genetic studies about MCD focusing on the PI3K/PTEN/AKT/mTOR pathway. Finally, we briefly discuss the diagnostic methods, disease models, and therapeutic strategies for MCD. The information will facilitate further research on MCD. Understanding the role of the PI3K/PTEN/AKT/mTOR pathway in MCD could lead to a novel strategy for treating MCD-related diseases.

Prenatal Imaging of Supratentorial Fetal Brain Malformation

This review article provides a comprehensive overview of fetal MR imaging in supratentorial cerebral malformations. It emphasizes the importance of fetal MR imaging as an adjunct diagnostic tool used alongside ultrasound, improving the detection and characterization of prenatal brain abnormalities. This article reviews a spectrum of cerebral malformations, their MR imaging features, and the clinical implications of these findings. Additionally, it outlines the growing importance of fetal MR imaging in the context of perinatal care.

Fetal Head and Neck Imaging

Prenatal MRI plays an essential role in the evaluation of the head and neck. This article overviews technical considerations and both isolated and syndromic anomalies of the fetal calvarium, globes and orbits, ears, maxilla, mandible, and neck.

The fetal brain: migration and gyration anomalies - pre- and postnatal correlations

The cerebral cortex represents a laminar structure of precisely spatially organized neurons in horizontal layers and vertical columns. Neurogenesis, neuronal migration and neuronal wiring are tightly regulated and coordinated procedures that result in the accurate formation of the human cerebral cortex. Abnormal fetal corticogenesis results in several types of migration and gyration anomalies, known as malformations of cortical development, which have long been a topic of investigation. According to the stage of cortical development that is affected, with diverse genetic and non-genetic etiologies, these malformations can cause abnormal head size, abnormal brain surface and abnormal cortical layering with various degrees of neurodevelopmental delay and epilepsy. The pathogenesis of these malformations is multifactorial and includes genetic mutations or environmental insults, acquired either in utero at varying stages of brain development or during the perinatal period after corticogenesis. In this article, we focus on cortical malformations detected on fetal MRI. We present the main antenatal findings that should raise suspicion for malformations of cortical development, together with findings that might be missed on prenatal imaging and describe the correlations between fetal and postnatal MRI.

Clinical Applications of Fetal MRI in the Brain

Fetal magnetic resonance imaging (MRI) has become a widely used tool in clinical practice, providing increased accuracy in prenatal diagnoses of congenital abnormalities of the brain, allowing for more accurate prenatal counseling, optimization of perinatal management, and in some cases fetal intervention. In this article, a brief description of how fetal ultrasound (US) and fetal MRI are used in clinical practice will be followed by an overview of the most common reasons for referral for fetal MRI of the brain, including ventriculomegaly, absence of the cavum septi pellucidi (CSP) and posterior fossa anomalies.

Emotional behavior and brain anatomy of the mdx52 mouse model of Duchenne muscular dystrophy

The exon-52-deleted mdx52 mouse is a critical model of Duchenne muscular dystrophy (DMD), as it features a deletion in a hotspot region of the DMD gene, frequently mutated in patients. Deletion of exon 52 impedes expression of several brain dystrophins (Dp427, Dp260 and Dp140), thus providing a key model for studying the cognitive impairment associated with DMD and testing rescuing strategies. Here, using in vivo magnetic resonance imaging and neurohistology, we found no gross brain abnormalities in mdx52 mice, suggesting that the neural dysfunctions in this model are likely at the level of brain cellular functionalities. Then, we investigated emotional behavior and fear learning performance of mdx52 mice compared to mdx mice that only lack Dp427 to focus on behavioral phenotypes that could be used in future comparative preclinical studies. mdx52 mice displayed enhanced anxiety and a severe impairment in learning an amygdala-dependent Pavlovian association. These replicable behavioral outcome measures are reminiscent of the internalizing problems reported in a quarter of DMD patients, and will be useful for preclinical estimation of the efficacy of treatments targeting brain dysfunctions in DMD.