Exploring intricate connectivity patterns for cognitive functioning and neurological disorders: incorporating frequency-domain NC method into fMRI analysis.

This study extends the application of the frequency-domain new causality method to functional magnetic resonance imaging analysis. Strong causality, weak causality, balanced causality, cyclic causality, and transitivity causality were constructed to simulate varying degrees of causal associations among multivariate functional-magnetic-resonance-imaging blood-oxygen-level-dependent signals. Data from 1,252 groups of individuals with different degrees of cognitive impairment were collected. The frequency-domain new causality method was employed to construct directed efficient connectivity networks of the brain, analyze the statistical characteristics of topological variations in brain regions related to cognitive impairment, and utilize these characteristics as features for training a deep learning model. The results demonstrated that the frequency-domain new causality method accurately detected causal associations among simulated signals of different degrees. The deep learning tests also confirmed the superior performance of new causality, surpassing the other three methods in terms of accuracy, precision, and recall rates. Furthermore, consistent significant differences were observed in the brain efficiency networks, where several subregions defined by the multimodal parcellation method of Human Connectome Project simultaneously appeared in the topological statistical results of different patient groups. This suggests a significant association between these fine-grained cortical subregions, driven by multimodal data segmentation, and human cognitive function, making them potential biomarkers for further analysis of Alzheimer's disease.

PET brain imaging in neurological disorders.

Brain disorders are a series of conditions with damage or loss of neurons, such as Parkinson's disease (PD), Alzheimer's disease (AD), or drug dependence. These individuals have gradual deterioration of cognitive, motor, and other central nervous system functions affected. This degenerative trajectory is intricately associated with dysregulations in neurotransmitter systems. Positron Emission Tomography (PET) imaging, employing radiopharmaceuticals and molecular imaging techniques, emerges as a crucial tool for detecting brain biomarkers. It offers invaluable insights for early diagnosis and distinguishing brain disorders. This article comprehensively reviews the application and progress of conventional and novel PET imaging agents in diagnosing brain disorders. Furthermore, it conducts a thorough analysis on merits and limitations. The article also provides a forward-looking perspective in the future development directions of PET imaging agents for diagnosing brain disorders and proposes potential innovative strategies. It aims to furnish clinicians and researchers with an all-encompassing overview of the latest advancements and forthcoming trends in the utilization of PET imaging for diagnosing brain disorders.

FDG PET in Neurological Manifestations of COVID-19.

ABSTRACT: Both the central and peripheral nervous systems can be affected in COVID-19. Although MRI is the primary investigative tool for neurological imaging, FDG PET may show additional areas of involvement in the brain in the form of regional hypometabolism or hypermetabolism, secondary to synaptic dysfunction and electrical or glial activation. We present a case series of 4 patients who had neurological symptoms attributable to COVID-19 infection with abnormalities in the brain FDG PET scan.

Brain magnetic resonance imaging findings in children with neurological complications of coronavirus disease 2019 (Omicron variant): a multicenter retrospective observational study.

BACKGROUND: An increasing rate of encephalopathy associated with coronavirus disease 2019 (COVID-19) has been observed among children. However, the literature on neuroimaging data in children with COVID-19 is limited. OBJECTIVE: To analyze brain magnetic resonance imaging (MRI) of pediatric COVID-19 patients with neurological complications. MATERIALS AND METHODS: This multicenter retrospective observational study analyzed clinical (n=102, 100%) and neuroimaging (n=93, 91.2%) data of 102 children with COVID-19 infections and comorbid acute neurological symptoms. These children were hospitalized at five pediatric intensive care units (PICUs) in China between December 1, 2022, and January 31, 2023. RESULTS: All patients were positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as detected via reverse transcriptase polymerase chain reaction. About 75.7% of the children were infected with the Omicron variant BF.7 strain. Brain MRI was performed 1-12 days following the onset of neurological symptoms, which revealed acute neuroimaging findings in 74.2% (69/93) of cases, including evidence of acute necrotizing encephalopathy (33/69, 47.8%), encephalitis (31/69, 44.9%), reversible splenial lesion syndrome (3/69, 4.3%), reversible posterior leukoencephalopathy (1/69, 1.4%), and hippocampal atrophy (1/69, 1.4%). CONCLUSIONS: Overall, these data highlighted five neuroimaging patterns associated with the outbreak of the SARS-CoV-2 Omicron variant, with acute necrotizing encephalopathy being the most common of these neuroimaging findings. Rarely, the brain MRI of these pediatric COVID-19 patients also demonstrate hippocampal atrophy.

Neurological Disorders and Women's Health: Contribution of Molecular Neuroimaging Techniques.

Sex differences in brain physiology and the mechanisms of drug action have been extensively reported. These biological variances, from structure to hormonal and genetic aspects, can profoundly influence healthy functioning and disease mechanisms and might have implications for treatment and drug development. Molecular neuroimaging techniques may help to disclose sex's impact on brain functioning, as well as the neuropathological changes underpinning several diseases. This narrative review summarizes recent lines of evidence based on PET and SPECT imaging, highlighting sex differences in normal conditions and various neurological disorders.

Imaging of brain barrier inflammation and brain fluid drainage in human neurological diseases.

The intricate relationship between the central nervous system (CNS) and the immune system plays a crucial role in the pathogenesis of various neurological diseases. Understanding the interactions among the immunopathological processes at the brain borders is essential for advancing our knowledge of disease mechanisms and developing novel diagnostic and therapeutic approaches. In this review, we explore the emerging role of neuroimaging in providing valuable insights into brain barrier inflammation and brain fluid drainage in human neurological diseases. Neuroimaging techniques have enabled us not only to visualize and assess brain structures, but also to study the dynamics of the CNS in health and disease in vivo. By analyzing imaging findings, we can gain a deeper understanding of the immunopathology observed at the brain-immune interface barriers, which serve as critical gatekeepers that regulate immune cell trafficking, cytokine release, and clearance of waste products from the brain. This review explores the integration of neuroimaging data with immunopathological findings, providing valuable insights into brain barrier integrity and immune responses in neurological diseases. Such integration may lead to the development of novel diagnostic markers and targeted therapeutic approaches that can benefit patients with neurological disorders.

Intranasal dexmedetomidine as premedication for magnetic resonance imaging examinations in dogs with neurological disorders mitigates hypotension and hypothermia.

OBJECTIVE: This study aimed to evaluate the safety and feasibility of intranasal administration of dexmedetomidine as a premedication for preventing hypotension and hypothermia in canine patients undergoing MRI examinations. ANIMALS: Dogs undergoing MRI examinations for neurological disorders were enrolled in this study. The dogs were randomly assigned: 15 to the N-Dex group (without premedication) and 13 to the Dex group (125 µg/m2 of dexmedetomidine, intranasally, as a premedication). METHODS: During the examination, pulse rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were recorded every 5 minutes for the first 30 minutes. Body temperature was measured before and after the examination. Any adverse events during the procedure were documented. RESULTS: Significant changes in pulse rate during the examination were not distinguishable. Although blood pressure and body temperature decreased in both groups under anesthesia, dogs in the Dex group had a significantly smaller drop in blood pressure and body temperature and fewer hypotension events than those in the N-Dex group MRI examinations of 1 hour's duration. Two dogs in the Dex group exhibited bradycardia at 45 and 60 minutes of MRI examination, which resolved after receiving atipamezole. CLINICAL RELEVANCE: Our results indicate that intranasal administration of 125 µg/m2 of dexmedetomidine as premedication is safe and can potentially mitigate hypothermia and hypotension in dogs with neurological disorders during MRI examinations.

Live Mapping of the Brain Extracellular Matrix and Remodeling in Neurological Disorders.

Live imaging of the brain extracellular matrix (ECM) provides vital insights into changes that occur in neurological disorders. Current techniques such as second or third-harmonic generation offer limited contrast for live imaging of the brain ECM. Here, a new method, pan-ECM via chemical labeling of extracellular proteins, is introduced for live brain ECM imaging. pan-ECM labels all major ECM components in live tissue including the interstitial matrix, basement membrane, and perineuronal nets. pan-ECM enables in vivo observation of the ECM heterogeneity between the glioma core and margin, as well as the assessment of ECM deterioration under stroke condition, without ECM shrinkage from tissue fixation. These findings indicate that the pan-ECM approach is a novel way to image the entire brain ECM in live brain tissue with optical resolution. pan-ECM has the potential to advance the understanding of ECM in brain function and neurological diseases.

Enlarged Perivascular Space and Index for Diffusivity Along the Perivascular Space as Emerging Neuroimaging Biomarkers of Neurological Diseases.

The existence of lymphatic vessels or similar clearance systems in the central nervous system (CNS) that transport nutrients and remove cellular waste is a neuroscientific question of great significance. As the brain is the most metabolically active organ in the body, there is likely to be a potential correlation between its clearance system and the pathological state of the CNS. Until recently the successive discoveries of the glymphatic system and the meningeal lymphatics solved this puzzle. This article reviews the basic anatomy and physiology of the glymphatic system. Imaging techniques to visualize the function of the glymphatic system mainly including post-contrast imaging techniques, indirect lymphatic assessment by detecting increased perivascular space, and diffusion tensor image analysis along the perivascular space (DTI-ALPS) are discussed. The pathological link between glymphatic system dysfunction and neurological disorders is the key point, focusing on the enlarged perivascular space (EPVS) and the index of diffusivity along the perivascular space (ALPS index), which may represent the activity of the glymphatic system as possible clinical neuroimaging biomarkers of neurological disorders. The pathological link between glymphatic system dysfunction and neurological disorders is the key point, focusing on the enlarged perivascular space (EPVS) and the index for of diffusivity along the perivascular space (ALPS index), which may represent the activity of the glymphatic system as possible clinical neuroimaging biomarkers of neurological disorders.

Clinical application of magnetic resonance elastography in pediatric neurological disorders.

Magnetic resonance elastography is a relatively new, rapidly evolving quantitative magnetic resonance imaging technique which can be used for mapping the viscoelastic mechanical properties of soft tissues. MR elastography measurements are akin to manual palpation but with the advantages of both being quantitative and being useful for regions which are not available for palpation, such as the human brain. MR elastography is noninvasive, well tolerated, and complements standard radiological and histopathological studies by providing in vivo measurements that reflect tissue microstructural integrity. While brain MR elastography studies in adults are becoming frequent, published studies on the utility of MR elastography in children are sparse. In this review, we have summarized the major scientific principles and recent clinical applications of brain MR elastography in diagnostic neuroscience and discuss avenues for impact in assessing the pediatric brain.

Imaging Approaches to Investigate Pathophysiological Mechanisms of Brain Disease in Zebrafish.

Zebrafish has become an essential model organism in modern biomedical research. Owing to its distinctive features and high grade of genomic homology with humans, it is increasingly employed to model diverse neurological disorders, both through genetic and pharmacological intervention. The use of this vertebrate model has recently enhanced research efforts, both in the optical technology and in the bioengineering fields, aiming at developing novel tools for high spatiotemporal resolution imaging. Indeed, the ever-increasing use of imaging methods, often combined with fluorescent reporters or tags, enable a unique chance for translational neuroscience research at different levels, ranging from behavior (whole-organism) to functional aspects (whole-brain) and down to structural features (cellular and subcellular). In this work, we present a review of the imaging approaches employed to investigate pathophysiological mechanisms underlying functional, structural, and behavioral alterations of human neurological diseases modeled in zebrafish.

Distinct features in adult polyglucosan body disease: a case series.

Adult polyglucosan body disease (APBD) is caused by bi-allelic pathogenic variants in GBE1 and typically shows middle age onset urinary symptoms followed by progressive gait disturbances and possibly cognitive decline. Here we present a Belgian cohort of four patients from three families showing both classical and atypical signs of APBD. By clinical phenotyping, detailed neuroimaging of both central nervous system and skeletal muscle, genetic and biochemical testing, we confront our findings with the classical presentation of adult polyglucosan body disease and emphasize the importance of a multidisciplinary approach when diagnosing these patients.

Use of metal-based contrast agents for in vivo MR and CT imaging of phagocytic cells in neurological pathologies.

The activation of phagocytic cells is a hallmark of many neurological diseases. Imaging them in their 3-dimensional cerebral environment over time is crucial to better understand their role in disease pathogenesis and to monitor their potential therapeutic effects. Phagocytic cells have the ability to internalize metal-based contrast agents both in vitro and in vivo and can thus be tracked by magnetic resonance imaging (MRI) or computed tomography (CT). In this review article, we summarize the different labelling strategies, contrast agents, and in vivo imaging modalities that can be used to monitor cells with phagocytic activity in the central nervous system using MRI and CT, with a focus on clinical applications. Metal-based nanoparticle contrast agents such as gadolinium, gold and iron are ideal candidates for these applications as they have favourable magnetic and/or radiopaque properties and can be fine-tuned for optimal uptake by phagocytic cells. However, they also come with downsides due to their potential toxicity, especially in the brain where they might accumulate. We therefore conclude our review by discussing the pitfalls, safety and potential for clinical translation of these metal-based neuroimaging techniques. Early results in patients with neuropathologies such as multiple sclerosis, stroke, trauma, cerebral aneurysm and glioblastoma are promising. If the challenges represented by safety issues are overcome, phagocytic cells imaging will be a very valuable tool for studying and understanding the inflammatory response and evaluating treatments that aim at mitigating this response in patients with neurological diseases.

Serum neurofilament light chain and initial severity of neurological disease predict the early neurological deterioration in Wilson's disease.

BACKGROUND: In Wilson's disease (WD), early neurological deterioration after treatment initiation is associated with poor outcomes; however, data on this phenomenon are limited. Our study analysed the frequency and risk factors of early neurological deterioration in WD. METHODS: Early neurological deterioration, within 6 months from diagnosis, was defined based on the Unified Wilson's Disease Rating Scale (UWDRS): any increase in part II or an increase of ≥ 4 in part III. In total, 61 newly diagnosed WD patients were included. UWDRS scores, brain magnetic resonance imaging (MRI) scores, copper metabolism parameters, treatment type and serum neuro-filament light chain (sNfL) concentrations at diagnosis were analysed as potential risk factors of early deterioration. RESULTS: Early neurological deterioration was observed in 16.3% of all WD patients; all cases of worsening occurred in the neurological phenotype (27.7%). Higher scores were seen in those who deteriorated compared with those who did not for UWDRS part II (4.3 ± 5.0 vs 2.0 ± 5.9; p < 0.05), UWDRS part III (21.5 ± 14.1 vs 9.3 ± 16.4; p < 0.01) and MRI-assessed chronic damage (3.2 ± 1.6 vs 1.4 ± 2.2; p = 0.006); all these variables indicated the initial severity of neurological disease. Pre-treatment sNfL concentrations were significantly higher in patients who deteriorated compared with those who did not (33.2 ± 23.5 vs 27.6 ± 62.7 pg/mL; p < 0.01). In univariate logistic regression amongst all patients, chronic damage MRI scores, UWDRS part III scores and sNfL concentrations predicated early deterioration. In the neurological WD, only sNFL were a significant predictor. In bivariate logistic regression amongst all patients, sNfL remained the only significant predictor of deterioration when corrected for MRI scores. CONCLUSION: sNfL concentrations are a promising biomarker of the risk of early neurological deterioration in WD.

Pediatric Functional Neurological Disorder: Demographic and Clinical Factors Impacting Care.

This is a multicenter retrospective EMR-based chart review of 88 patients aged 3-21 years admitted for evaluation of functional neurologic disorder (FND). We sought to establish characteristics associated with FND, calculate incidence of abnormal neurodiagnostic findings, and determine features associated with variability in workup and treatment. FND patients were 65% female, 40% White, 33% Hispanic, and 88% primarily English speaking with median 13.9 years. We detected variability in management by age, ethnicity, psychiatric comorbidity, and hospital site. Our findings suggest limited utility to CTs in this setting (100% normal) and that workup can be safely informed by physical exam, which predicted abnormal MRI and LP results. We favor screening for adverse childhood experiences in FND patients. Hospitalization may be a rare opportunity for psychiatry contact.

A review on investigation of the basic contrast mechanism underlying multidimensional diffusion MRI in assessment of neurological disorders.

INTRODUCTION: Multidimensional diffusion MRI (MDD MRI) is a novel diffusion technique that uses advanced gradient waveforms for microstructural tissue characterization to provide information about average rate, anisotropy and orientation of the diffusion and to disentangle the signal fraction from specific cell types i.e., elongated cells, isotropic cells and free water. AIM: To review the diagnostic potential of MDD MRI in the clinical setting for microstructural tissue characterization in patients with neurological disorders to aid in patient care and treatment. METHOD: A scoping review on the clinical applications of MDD MRI was conducted from original articles published in PubMed and Scopus from 2015 to 2021 using the keywords "Multidimensional diffusion MRI" OR "diffusion tensor distribution" OR "Tensor-Valued Diffusion" OR "b-tensor encoding" OR "microscopic diffusion anisotropy" OR "microscopic anisotropy" OR "microscopic fractional anisotropy" OR "double diffusion encoding" OR "triple diffusion encoding" OR "double pulsed field gradients" OR "double wave vector" OR "correlation tensor imaging" AND "brain" OR "axons". RESULTS: Initially 145 articles were screened and after applying inclusion and exclusion criteria, nine articles were included in the final analysis. In most of these studies, microscopic diffusion anisotropy within the lesion showed deviation from the normal-appearing tissue. CONCLUSION: Multidimensional diffusion MRI can provide better quantification and visualization of tissue microstructure than conventional diffusion MRI and can be used in the clinical setting for diagnosis of neurological disorders.

Magnetic resonance spectroscopy as a promising modality for assessing ketogenic diet impact on the level of cerebral metabolites in the treatment of certain neurological disorders.

INTRODUCTION AND OBJECTIVE: The ketogenic diet (KD) is a high-fat, adequate-protein, low-carbohydrate diet that is getting more and more widespread in medicine. This dietary intervention causes changes in cerebral metabolism, which are considered potentially beneficial in patients with neurological disorders, but its impact should be controlled and assessed individually. The aim of this review is to provide an update of existing evidence concerning the utility of magnetic resonance spectroscopy (MRS) in monitoring shifts in the cerebral metabolism during ketogenic diet in patients with neurological disorders. REVIEW METHODS: The latest available literature was reviewed by May 13, 2021 using the PubMed, Web of Science and Google Scholar databases. There were 13 papers selected for analysis after reading the title, abstracts and whole text, meeting the assumed criteria. ABBREVIATED DESCRIPTION OF THE STATE OF KNOWLEDGE: MRS is a non-invasive imaging method providing information about the metabolism of brain tissues and playing an increasingly important role in monitoring the concentrations of cerebral metabolites in the course of such neurological disorders as primary brain tumour, epilepsy during KD. Recent trials prove that inverse correlation between serum ß-hydroxybutyrate levels and N-acetylaspartate in brain tissue confirm antiepileptogenic properties of KD. Furthermore, ketone concentrations including ß-hydroxybutyrate and acetone in both lesional and contralateral brain are referred to as correlating with average ketonuria in patients with primary brain tumou. SUMMARY: MRS is a feasible tool for detecting cerebral metabolic shifts linked to a ketogenic diet. However, further studies confirming MR spectroscopy utility in monitoring ketogenic diet treatment in patients with neurological disorders are needed.