Use of Advanced Magnetic Resonance Imaging Techniques in Neuromyelitis Optica Spectrum Disorder

Update on the diagnosis and treatment of neuromyelitis optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part II: Attack therapy and long-term management

This manuscript presents practical recommendations for managing acute attacks and implementing preventive immunotherapies for neuromyelitis optica spectrum disorders (NMOSD), a rare autoimmune disease that causes severe inflammation in the central nervous system (CNS), primarily affecting the optic nerves, spinal cord, and brainstem. The pillars of NMOSD therapy are attack treatment and attack prevention to minimize the accrual of neurological disability. Aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) are a diagnostic marker of the disease and play a significant role in its pathogenicity. Recent advances in understanding NMOSD have led to the development of new therapies and the completion of randomized controlled trials. Four preventive immunotherapies have now been approved for AQP4-IgG-positive NMOSD in many regions of the world: eculizumab, ravulizumab - most recently-, inebilizumab, and satralizumab. These new drugs may potentially substitute rituximab and classical immunosuppressive therapies, which were as yet the mainstay of treatment for both, AQP4-IgG-positive and -negative NMOSD. Here, the Neuromyelitis Optica Study Group (NEMOS) provides an overview of the current state of knowledge on NMOSD treatments and offers statements and practical recommendations on the therapy management and use of all available immunotherapies for this disease. Unmet needs and AQP4-IgG-negative NMOSD are also discussed. The recommendations were developed using a Delphi-based consensus method among the core author group and at expert discussions at NEMOS meetings.

Update on the diagnosis and treatment of neuromyelits optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part I: Diagnosis and differential diagnosis

The term 'neuromyelitis optica spectrum disorders' (NMOSD) is used as an umbrella term that refers to aquaporin-4 immunoglobulin G (AQP4-IgG)-positive neuromyelitis optica (NMO) and its formes frustes and to a number of closely related clinical syndromes without AQP4-IgG. NMOSD were originally considered subvariants of multiple sclerosis (MS) but are now widely recognized as disorders in their own right that are distinct from MS with regard to immunopathogenesis, clinical presentation, optimum treatment, and prognosis. In part 1 of this two-part article series, which ties in with our 2014 recommendations, the neuromyelitis optica study group (NEMOS) gives updated recommendations on the diagnosis and differential diagnosis of NMOSD. A key focus is on differentiating NMOSD from MS and from myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD), which shares significant similarity with NMOSD with regard to clinical and, partly, radiological presentation, but is a pathogenetically distinct disease. In part 2, we provide updated recommendations on the treatment of NMOSD, covering all newly approved drugs as well as established treatment options.

Assessment of intelligence quotient in patients with neuromyelitis optica spectrum disease and multiple sclerosis

BACKGROUND

Cognitive impairment is common in people living with neuromyelitis optica spectrum disease (NMOSD) and multiple sclerosis (MS). However, there is little published data on intelligence quotient (IQ) in NMOSD patients. Therefore, we performed the present study to compare IQ scores across NMOSD, MS, and control groups.

METHOD

In this cross-sectional study, 49 NMOSD (30 with positive aquaporin4 antibody), 41 MS, and 20 control individuals were recruited. The IQ score for each person was measured using Wechsler Adult Intelligence Scale-Revised (WAIS-R). Participants were reported on eleven scores of subsets, verbal IQ (VIQ), performance IQ (PIQ), and full score IQ (FSIQ).

RESULT

The scores of FSIQ, VIQ, PIQ, vocabulary, similarities, and digit-symbol in NMOSD and MS individuals were lower than the control group. Relative to control, NMOSD patients reported a lower score of information. We found no difference between NMOSD and MS groups, except in vocabulary and similarities. No significant difference between seropositive and seronegative NMOSD groups was observed except for the information and block design. In NMOSD group, a greater EDSS score was associated with decreased scores of FSIQ, VIQ, and PIQ. Being employed and being married were associated with greater scores of VIQ and PIQ, respectively. In both NMOSD and MS groups, advanced education was associated with increased scores of FSIQ and VIQ.

CONCLUSION

Our study showed decreased IQ scores in NMOSD and MS. Further studies are required to examine intellectual quotient in people with NMOSD and MS.

Diagnostik der Neuromyelitis-optica-Spektrum-Erkrankung (NMOSD) und der MOG-Antikörper-assoziierten Erkrankung (MOGAD)

Die Aquaporin-4-Antikörper-positive Neuromyelitis-optica-Spektrum-Erkrankung (engl. NMOSD) und die Myelin-Oligodendrozyten-Glykoprotein-Antikörper-assoziierte Erkrankung (engl. MOGAD) sind Autoimmunerkrankungen des zentralen Nervensystems. Typische Erstmanifestationen sind bei Erwachsenen Optikusneuritis und Myelitis. Eine Beteiligung auch von Hirn und Hirnstamm, spätestens im weiteren Verlauf, ist häufig. Während die NMOSD nahezu immer schubförmig verläuft, nimmt die MOGAD gelegentlich einen monophasischen Verlauf. Die Differenzialdiagnostik ist anspruchsvoll und stützt sich auf u. a. auf radiologische und serologische Befunde. Die Abgrenzung von der häufigeren neuroinflammatorischen Erkrankung, Multiple Sklerose (MS), ist von erheblicher Bedeutung, da sich Behandlung und langfristige Prognose von NMOSD, MOGAD und MS wesentlich unterscheiden. Die vielfältigen Symptome und die umfangreiche Diagnostik machen eine enge Zusammenarbeit zwischen Ophthalmologie, Neurologie und Radiologie erforderlich. Dieser Artikel gibt einen Überblick über typische MRT-Befunde und die serologische Antikörperdiagnostik bei NMOSD und MOGAD. Zwei illustrative Fallberichte aus der ärztlichen Praxis ergänzen die Darstellung.

A pilot study of combined optical coherence tomography and diffusion tensor imaging method for evaluating microstructural change in the visual pathway of pituitary adenoma patients

Background

RNFL thickness measured by optical coherence tomography (OCT) and visual pathway measured by diffusion tensor imaging (DTI) can be used to predict visual field recovery, respectively. However, the relationship between RNFL thickness and visual pathway injury in patients with pituitary adenoma (PA) remains unclear. This study aims to evaluate the combining DTI and OCT methods in observing the microstructural change in the visual pathway in patients with PA.

Methods

Twenty-nine patients who were diagnosed with PA were included in the study group, and 29 healthy subjects were included as the control group. OCT detected the thickness of circumpapillary retinal nerve fiber layer (CP-RNFL) and ganglion cell layer (GCL). DTI measured the values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Correlation between CP-RNFL and GCL thickness and FA and ADC values was analyzed in the study group.

Results

Compared with the control group, the FA values of the bilateral optic nerve, chiasma, bilateral optic tract, and left optic radiation in the study group were reduced, and the ADC values of the bilateral optic nerve and optic chiasma were increased. Correlation analysis showed that the FA value of the optic chiasma was positively correlated with the average thickness of RNFL, the CP-RNFL thickness in the nasal and temporal retinal quadrants in both eyes, as well as the thickness of macular ring GCL in the nasal, supra, and inferior quadrants. The FA values of the optic nerve, optic chiasma, optic tract, and optic radiation were positively correlated with CP-RNFL thickness in the nasal and temporal quadrants.

Conclusion

Combined DTI and OCT can provide a comprehensive understanding of the microscopic changes in the structure and function of the whole visual pathway in patients with PA.

Elucidating distinct clinico-radiologic signatures in the borderland between neuromyelitis optica and multiple sclerosis

BACKGROUND

Separating antibody-negative neuromyelitis optica spectrum disorders (NMOSD) from multiple sclerosis (MS) in borderline cases is extremely challenging due to lack of biomarkers. Elucidating different pathologies within the likely heterogenous antibody-negative NMOSD/MS overlap syndrome is, therefore, a major unmet need which would help avoid disability from inappropriate treatment.

OBJECTIVE

In this study we aimed to identify distinct subgroups within the antibody-negative NMOSD/MS overlap syndrome.

METHODS

Twenty-five relapsing antibody-negative patients with NMOSD features underwent a prospective brain and spinal cord MRI. Subgroups were identified by an unsupervised algorithm based on pre-selected NMOSD/MS discriminators.

RESULTS

Four subgroups were identified. Patients from Group 1 termed "MS-like" (n = 6) often had central vein sign and cortical lesions (83% and 67%, respectively). All patients from Group 2 ("spinal MS-like", 8) had short-segment myelitis and no MS-like brain lesions. Group 3 ("classic NMO-like", 6) had high percentage of bilateral optic neuritis and longitudinally extensive transverse myelitis (LETM, 80% and 60%, respectively) and normal brain appearance (100%). Group 4 ("NMO-like with brain involvement", 5) typically had a history of NMOSD-like brain lesions and LETM. When compared with other groups, Group 4 had significantly decreased fractional anisotropy in non-lesioned tracts (0.46 vs. 0.49, p = 0.003) and decreased thalamus volume (0.84 vs. 0.98, p = 0.04).

CONCLUSIONS

NMOSD/MS cohort contains distinct subgroups likely corresponding to different pathologies and requiring tailored treatment. We propose that non-conventional MRI might help optimise diagnosis in these challenging patients.

Proton and Multinuclear Spectroscopy of the Pediatric Brain

Magnetic resonance spectroscopy (MRS) is a valuable adjunct to structural brain imaging. State-of-the-art MRS has benefited greatly from recent technical advancements. Neurometabolic alterations in pediatric brain diseases have implications for diagnosis, prognosis, and therapy. Herein, the authors discuss MRS technical considerations and applications in the setting of various pediatric disease processes including tumors, metabolic diseases, hypoxic/ischemic encephalopathy/stroke, epilepsy, demyelinating disease, and infection.

Retinal optical coherence tomography and magnetic resonance imaging in neuromyelitis optica spectrum disorders and MOG-antibody associated disorders: an updated review

INTRODUCTION

Neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein IgG antibody-associated disorders (MOGAD) comprise two groups of rare neuroinflammatory diseases that cause attack-related damage to the central nervous system (CNS). Clinical attacks are often characterized by optic neuritis, transverse myelitis, and to a lesser extent, brainstem encephalitis/area postrema syndrome. Retinal optical coherence tomography (OCT) is a non-invasive technique that allows for in vivo thickness quantification of the retinal layers. Apart from OCT, magnetic resonance imaging (MRI) plays an increasingly important role in NMOSD and MOGAD diagnosis based on the current international diagnostic criteria. Retinal OCT and brain/spinal cord/optic nerve MRI can help to distinguish NMOSD and MOGAD from other neuroinflammatory diseases, particularly from multiple sclerosis, and to monitor disease-associated CNS-damage.

AREAS COVERED

This article summarizes the current status of imaging research in NMOSD and MOGAD, and reviews the clinical relevance of OCT, MRI and other relevant imaging techniques for differential diagnosis, screening and monitoring of the disease course.

EXPERT OPINION

Retinal OCT and MRI can visualize and quantify CNS damage in vivo, improving our understanding of NMOSD and MOGAD pathology. Further efforts on the standardization of these imaging techniques are essential for implementation into clinical practice and as outcome parameters in clinical trials.

Multi-parametric MRI phenotype with trustworthy machine learning for differentiating CNS demyelinating diseases

Background

Misdiagnosis of multiple sclerosis (MS) and neuromyelitis optica (NMO) may delay the treatment, resulting in poor prognosis. However, the precise identification of these two diseases is still challenging in clinical practice. We aimed to evaluate the value of quantitative radiomic features extracted from the brain white matter lesions for differential diagnosis of MS and NMO.

Methods

We recruited 116 CNS demyelinating patients including 78 MS, and 38 NMO. Three neuroradiologists performed visual differential diagnosis based on brain MRI for comparison purpose. A multi-level scheme was designed to harness the selection of discriminative and stable radiomics features extracted from brain while mater lesions in T1-MPRAGE, T2 sequences and clinical factors. Based on the imaging phenotype composed of the selected radiomic and clinical features, Multi-parametric Multivariate Random Forest (MM-RF) model was constructed and verified with both 10-fold cross-validation and independent testing. Result interpretation was provided to build trust in diagnostic decisions.

Results

Eighty-six patients were randomly selected to form the training set while the rest 30 patients for independent testing. On the training set, our MM-RF model achieved accuracy 0.849 and AUC 0.826 in 10-fold cross-validation, which were significantly higher than clinical visual analysis (0.709 and 0.683, p < 0.05). In the independent testing, the MM-RF model achieved AUC 0.902, accuracy 0.871, sensitivity 0.873, specificity 0.869, respectively. Furthermore, age, sex and EDSS were found mildly correlated with the radiomic features (p of all < 0.05).

Conclusions

Multi-parametric radiomic features have potential as practical quantitative imaging biomarkers for differentiating MS from NMO.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03015-w.

An In-vivo 1H-MRS short-echo time technique at 7T: Quantification of metabolites in chronic multiple sclerosis and neuromyelitis optica brain lesions and normal appearing brain tissue

Magnetic Resonance Spectroscopy (MRS) allows for the non-invasive quantification of neurochemicals and has the potential to differentiate between the pathologically distinct diseases, multiple sclerosis (MS) and AQP4Ab-positive neuromyelitis optica spectrum disorder (AQP4Ab-NMOSD). In this study we characterised the metabolite profiles of brain lesions in 11 MS and 4 AQP4Ab-NMOSD patients using an optimised MRS methodology at ultra-high field strength (7T) incorporating correction for T2 water relaxation differences between lesioned and normal tissue. MS metabolite results were in keeping with the existing literature: total N-acetylaspartate (NAA) was lower in lesions compared to normal appearing brain white matter (NAWM) with reciprocal findings for myo-Inositol. An unexpected subtlety revealed by our technique was that total NAA differences were likely driven by NAA-glutamate (NAAG), a ubiquitous CNS molecule with functions quite distinct from NAA though commonly quantified together with NAA in MRS studies as total NAA. Surprisingly, AQP4Ab-NMOSD showed no significant differences for total NAA, NAA, NAAG or myo-Inositol between lesion and NAWM sites, nor were there any differences between MS and AQP4Ab-NMOSD for a priori hypotheses. Post-hoc testing revealed a significant correlation between NAWM Ins:NAA and disability (as measured by EDSS) for disease groups combined, driven by the AP4Ab-NMOSD group. Utilising an optimised MRS methodology, our study highlights some under-explored subtleties in MRS profiles, such as the absence of myo-Inositol concentration differences in AQP4Ab-NMOSD brain lesions versus NAWM and the potential influence of NAAG differences between lesions and normal appearing white matter in MS.

A window into the future? MRI for evaluation of neuromyelitis optica spectrum disorder throughout the disease course

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, inflammatory disease of the central nervous system marked by relapses often associated with poor recovery and long-term disability. Magnetic resonance imaging (MRI) is recognized as an important tool for timely diagnosis of NMOSD as, in combination with serologic testing, it aids in distinguishing NMOSD from possible mimics. Although the role of MRI for disease monitoring after diagnosis is not as well established, MRI may provide important prognostic information and help differentiate between relapses and pseudorelapses. Increasing evidence of subclinical disease activity and the emergence of newly approved, highly effective immunotherapies for NMOSD adjure us to re-evaluate MRI as a tool to guide optimal treatment selection and escalation throughout the disease course. In this article we review the role of MRI in NMOSD diagnosis, prognostication, disease monitoring, and treatment selection.

MRI characteristics of Japanese macaque encephalomyelitis: Comparison to human diseases

BACKGROUND AND PURPOSE

To describe MRI findings in Japanese macaque encephalomyelitis (JME) with emphasis on lesion characteristics, lesion evolution, normal-appearing brain tissue, and similarities to human demyelinating disease.

METHODS

MRI data were obtained from 114 Japanese macaques, 30 presenting neurological signs of JME. All animals were screened for presence of T2 -weighted white matter signal hyperintensities; animals with behavioral signs of JME were additionally screened for contrast-enhancing lesions. Whole-brain quantitative T1 maps were collected, and histogram analysis was performed with regression across age to evaluate microstructural changes in normal appearing brain tissue in JME and neurologically normal animals. Quantitative estimates of blood-brain-barrier (BBB) permeability to gadolinium-based-contrast agent (GBCA) were obtained in acute, GBCA-enhancing lesions. Longitudinal imaging data were acquired for 15 JME animals.

RESULTS

One hundred and seventy-three focal GBCA-enhancing lesions were identified in 30 animals demonstrating behavioral signs of neurological dysfunction. JME GBCA-enhancing lesions were typically focal and ovoid, demonstrating highest BBB GBCA permeability in the lesion core, similar to acute, focal multiple sclerosis lesions. New GBCA-enhancing lesions arose rapidly from normal-appearing tissue, and BBB permeability remained elevated for weeks. T1 values in normal-appearing tissue were significantly associated with age, but not with sex or disease.

CONCLUSIONS

Intense, focal neuroinflammation is a key MRI finding in JME. Several features of JME compare directly to human inflammatory demyelinating diseases. Investigation of JME combined with the development and validation of noninvasive imaging biomarkers offers substantial potential to improve diagnostic specificity and contribute to the understanding of human demyelinating diseases.

E.U. paediatric MOG consortium consensus: Part 2 - Neuroimaging features of paediatric myelin oligodendrocyte glycoprotein antibody-associated disorders

Imaging plays a crucial role in differentiating the spectrum of paediatric acquired demyelinating syndromes (ADS), which apart from myelin oligodendrocyte glycoprotein antibody associated disorders (MOGAD) includes paediatric multiple sclerosis (MS), aquaporin-4 antibody neuromyelitis optica spectrum disorders (NMOSD) and unclassified patients with both monophasic and relapsing ADS. In contrast to the imaging characteristics of children with MS, children with MOGAD present with diverse imaging patterns which correlate with the main demyelinating phenotypes as well as age at presentation. In this review we describe the common neuroradiological features of children with MOGAD such as acute disseminated encephalomyelitis, optic neuritis, transverse myelitis, AQP4 negative NMOSD. In addition, we report newly recognized presentations also associated with MOG-ab such as the 'leukodystophy-like' phenotype and autoimmune encephalitis with predominant involvement of cortical and deep grey matter structures. We further delineate the features, which may help to distinguish MOGAD from other ADS and discuss the future role of MR-imaging in regards to treatment decisions and prognosis in children with MOGAD. Finally, we propose an MRI protocol for routine examination and discuss new imaging techniques, which may help to better understand the neurobiology of MOGAD.

Ultra-high-field 7-T MRI in multiple sclerosis and other demyelinating diseases: from pathology to clinical practice

Magnetic resonance imaging (MRI) is essential for the early diagnosis of multiple sclerosis (MS), for investigating the disease pathophysiology, and for discriminating MS from other neurological diseases. Ultra-high-field strength (7-T) MRI provides a new tool for studying MS and other demyelinating diseases both in research and in clinical settings. We present an overview of 7-T MRI application in MS focusing on increased sensitivity and specificity for lesion detection and characterisation in the brain and spinal cord, central vein sign identification, and leptomeningeal enhancement detection. We also discuss the role of 7-T MRI in improving our understanding of MS pathophysiology with the aid of metabolic imaging. In addition, we present 7-T MRI applications in other demyelinating diseases. 7-T MRI allows better detection of the anatomical, pathological, and functional features of MS, thus improving our understanding of MS pathology in vivo. 7-T MRI also represents a potential tool for earlier and more accurate diagnosis.

Neuromyelitis optica

Neuromyelitis optica (NMO; also known as Devic syndrome) is a clinical syndrome characterized by attacks of acute optic neuritis and transverse myelitis. In most patients, NMO is caused by pathogenetic serum IgG autoantibodies to aquaporin 4 (AQP4), the most abundant water-channel protein in the central nervous system. In a subset of patients negative for AQP4-IgG, pathogenetic serum IgG antibodies to myelin oligodendrocyte glycoprotein, an antigen in the outer myelin sheath of central nervous system neurons, are present. Other causes of NMO (such as paraneoplastic disorders and neurosarcoidosis) are rare. NMO was previously associated with a poor prognosis; however, treatment with steroids and plasma exchange for acute attacks and with immunosuppressants (in particular, B cell-depleting agents) for attack prevention has greatly improved the long-term outcomes. Recently, a number of randomized controlled trials have been completed and the first drugs, all therapeutic monoclonal antibodies, have been approved for the treatment of AQP4-IgG-positive NMO and its formes frustes.

Differences in Advanced Magnetic Resonance Imaging in MOG-IgG and AQP4-IgG Seropositive Neuromyelitis Optica Spectrum Disorders: A Comparative Study

Aims: To explore differences in advanced brain magnetic resonance imaging (MRI) characteristics between myelin oligodendrocyte (MOG) immunoglobulin (IgG) and aquaporin-4 (AQP4) IgG seropositive (+) neuromyelitis optica spectrum disorders (NMOSD).

Methods: 33 AQP4-IgG and 18 MOG-IgG seropositive NMOSD patients and 61 healthy control (HC) subjects were included. All 112 participants were scanned with the same standardized MRI-protocol on a 3-Tesla MRI-scanner. Brain volume and diffusion tensor imaging (DTI) parameters were assessed.

Results: MOG-IgG+ patients showed reduced parallel diffusivity within white matter tracts compared to HC whereas AQP4-IgG+ showed no significant brain parenchymal damage in DTI analysis. AQP4-IgG+ patients showed reduced whole brain volumes and reduced volumes of several deep gray matter structures compared to HC whereas MOG-IgG+ patients did not show reduced brain or deep gray matter volumes compared to HC.

Conclusions: Microstructural brain parenchymal damage in MOG-IgG+ patients was more pronounced than in AQP4-IgG+ patients, compared with HC, whereas normalized brain volume reduction was more severe in AQP4-IgG+ patients. Longitudinal imaging studies are warranted to further investigate this trend in NMOSD. Our results suggest that MOG-IgG+ and AQP4-IgG+ NMOSD patients differ in cerebral MRI characteristics. Advanced MRI analysis did not help to differentiate between MOG-IgG+ and AQP4-IgG+ patients in our study.

Brain MRI characteristics in neuromyelitis optica spectrum disorders: A large multi-center retrospective study in China

PURPOSE

To investigate the brain MRI features in neuromyelitis optica spectrum disorders (NMOSD) and its clinical relevance in a large multi-center cohort in China.

METHODS

270 NMOSD patients were recruited from seven centers. The brain MRI were classified as normal, NMOSD-specific lesions, multiple sclerosis-like, nonspecific white matter changes. Brain volumes including whole brain, white, gray matter, cortex and subcortex gray matter volume were measured. The relationship between MRI measures, clinical disability and cognitive impairment were investigated.

RESULTS

98 patients (36.3%) had normal brain MRI; 48 patients (17.7%) had NMOSD-specific lesions located in dorsal brainstem, corticospinal tract corpus, callosum and periependymal lesions surrounding the ventricular system; 16 patients (6%) had multiple sclerosis-like lesions; and 108 patients (40%) had nonspecific white matter changes. NMOSD patients with brain lesions had a trend of lower subcortex gray matter volume compared to patients without lesions. 52.5% patients with normal brain MRI and 50.8% patients with abnormal brain MRI showed cognitive impairment. No significant differences were identified in brain volume between cognitive impairment and cognitive preserved groups.

CONCLUSION

In this large multicenter NMOSD cohort, nonspecific white matter changes were the most common findings (40%). NMOSD patients with brain lesions demonstrated a trend of having lower brain volume than patients without lesions. Approximately 50% NMOSD patients presented cognitive impairment independent of brain lesions.

Visualizing the Central Nervous System: Imaging Tools for Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are autoimmune central nervous system conditions with increasing incidence and prevalence. While MS is the most frequent inflammatory CNS disorder in young adults, NMOSD is a rare disease, that is pathogenetically distinct from MS, and accounts for approximately 1% of demyelinating disorders, with the relative proportion within the demyelinating CNS diseases varying widely among different races and regions. Most immunomodulatory drugs used in MS are inefficacious or even harmful in NMOSD, emphasizing the need for a timely and accurate diagnosis and distinction from MS. Despite distinct immunopathology and differences in disease course and severity there might be considerable overlap in clinical and imaging findings, posing a diagnostic challenge for managing neurologists. Differential diagnosis is facilitated by positive serology for AQP4-antibodies (AQP4-ab) in NMOSD, but might be difficult in seronegative cases. Imaging of the brain, optic nerve, retina and spinal cord is of paramount importance when managing patients with autoimmune CNS conditions. Once a diagnosis has been established, imaging techniques are often deployed at regular intervals over the disease course as surrogate measures for disease activity and progression and to surveil treatment effects. While the application of some imaging modalities for monitoring of disease course was established decades ago in MS, the situation is unclear in NMOSD where work on longitudinal imaging findings and their association with clinical disability is scant. Moreover, as long-term disability is mostly attack-related in NMOSD and does not stem from insidious progression as in MS, regular follow-up imaging might not be useful in the absence of clinical events. However, with accumulating evidence for covert tissue alteration in NMOSD and with the advent of approved immunotherapies the role of imaging in the management of NMOSD may be reconsidered. By contrast, MS management still faces the challenge of implementing imaging techniques that are capable of monitoring progressive tissue loss in clinical trials and cohort studies into treatment algorithms for individual patients. This article reviews the current status of imaging research in MS and NMOSD with an emphasis on emerging modalities that have the potential to be implemented in clinical practice.

Differentiate aquaporin-4 antibody negative neuromyelitis optica spectrum disorders from multiple sclerosis by multimodal advanced MRI techniques

BACKGROUND

It is clinically essential to distinguish aquaporin-4 antibody (AQP4-Ab) negative neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS) because of different therapeutic strategies. Since clinical and lesion features may not allow the distinction, we aimed to identify advanced imaging features that could improve the distinction between two disorders.

METHODS

Multimodal imaging measures included fractional anisotropy, mean, axial, radial diffusivity (MD, AD, RD) and kurtosis (MK, AK, RK) from diffusion kurtosis imaging; functional connectivity strength (FCS) and density, regional homogeneity, amplitude of low frequency fluctuations from resting-state functional MRI; gray matter volume from structural MRI; and cerebral blood flow from arterial spin labeling imaging. Voxel-wise comparisons were performed to identify inter-group differences in imaging measures, and the performance of differentiating these two disorders was estimated by receiver operating characteristic curves.

RESULTS

Compared to MS, patients with AQP4-Ab negative NMOSD showed decreased MD and AD but increased MK and AK in white matter regions; and reduced FCS in the occipital cortex (P < 0.05, FWE corrected). The joint-use of these five imaging measures distinguished the two disorders with an accuracy of 94% (P < 0.001, 95%CI = 0.84-0.98). Other imaging measures showed no significant differences between the two patient groups.

CONCLUSIONS

The study showed less white matter damage and a more severe functional disconnection of the occipital cortex in patients with AQP4-Ab negative NMOSD compared to MS. The combined use of diffusion and functional connectivity could facilitate a better distinction between NMO and MS with seronegative AQP4-Ab in clinical management.

Imaging markers of disability in aquaporin-4 immunoglobulin G seropositive neuromyelitis optica: a graph theory study

Neuromyelitis optica spectrum disorders lack imaging biomarkers associated with disease course and supporting prognosis. This complex and heterogeneous set of disorders affects many regions of the central nervous system, including the spinal cord and visual pathway. Here, we use graph theory-based multimodal network analysis to investigate hypothesis-free mixed networks and associations between clinical disease with neuroimaging markers in 40 aquaporin-4-immunoglobulin G antibody seropositive patients (age = 48.16 ± 14.3 years, female:male = 36:4) and 31 healthy controls (age = 45.92 ± 13.3 years, female:male = 24:7). Magnetic resonance imaging measures included total brain and deep grey matter volumes, cortical thickness and spinal cord atrophy. Optical coherence tomography measures of the retina and clinical measures comprised of clinical attack types and expanded disability status scale were also utilized. For multimodal network analysis, all measures were introduced as nodes and tested for directed connectivity from clinical attack types and disease duration to systematic imaging and clinical disability measures. Analysis of variance, with group interactions, gave weights and significance for each nodal association (hyperedges). Connectivity matrices from 80% and 95% F-distribution networks were analyzed and revealed the number of combined attack types and disease duration as the most connected nodes, directly affecting changes in several regions of the central nervous system. Subsequent multivariable regression models, including interaction effects with clinical parameters, identified associations between decreased nucleus accumbens (β = −0.85, P = 0.021) and caudate nucleus (β = −0.61, P = 0.011) volumes with higher combined attack type count and longer disease duration, respectively. We also confirmed previously reported associations between spinal cord atrophy with increased number of clinical myelitis attacks. Age was the most important factor associated with normalized brain volume, pallidum volume, cortical thickness and the expanded disability status scale score. The identified imaging biomarker candidates warrant further investigation in larger-scale studies. Graph theory-based multimodal networks allow for connectivity and interaction analysis, where this method may be applied in other complex heterogeneous disease investigations with different outcome measures.

Imaging in Neuro-ophthalmology

PURPOSE OF REVIEW

This article discusses an approach to imaging in patients with neuro-ophthalmologic disorders, with emphasis on the clinical-anatomic localization of lesions affecting afferent and efferent visual function.

RECENT FINDINGS

Advances in MRI, CT, ultrasound, and optical coherence tomography have changed how neuro-ophthalmic disorders are diagnosed and followed in the modern clinical era.

SUMMARY

The advantages, disadvantages, and indications for various imaging techniques for neuro-ophthalmologic disorders are discussed, with a view to optimizing how these tools can be used to enhance patient care.

Collaborative International Research in Clinical and Longitudinal Experience Study in NMOSD

Objective

To develop a resource of systematically collected, longitudinal clinical data and biospecimens for assisting in the investigation into neuromyelitis optica spectrum disorder (NMOSD) epidemiology, pathogenesis, and treatment.

Methods

To illustrate its research-enabling purpose, epidemiologic patterns and disease phenotypes were assessed among enrolled subjects, including age at disease onset, annualized relapse rate (ARR), and time between the first and second attacks.

Results

As of December 2017, the Collaborative International Research in Clinical and Longitudinal Experience Study (CIRCLES) had enrolled more than 1,000 participants, of whom 77.5% of the NMOSD cases and 71.7% of the controls continue in active follow-up. Consanguineous relatives of patients with NMOSD represented 43.6% of the control cohort. Of the 599 active cases with complete data, 84% were female, and 76% were anti-AQP4 seropositive. The majority were white/Caucasian (52.6%), whereas blacks/African Americans accounted for 23.5%, Hispanics/Latinos 12.4%, and Asians accounted for 9.0%. The median age at disease onset was 38.4 years, with a median ARR of 0.5. Seropositive cases were older at disease onset, more likely to be black/African American or Hispanic/Latino, and more likely to be female.

Conclusions

Collectively, the CIRCLES experience to date demonstrates this study to be a useful and readily accessible resource to facilitate accelerating solutions for patients with NMOSD.

Cognitive Impairment in Neuromyelitis Optica Spectrum Disorders: A Review of Clinical and Neuroradiological Features

Neuromyelitis optica spectrum disorders (NMOSD) are mostly relapsing autoimmune inflammatory disorders of the central nervous system (CNS) with optic neuritis, myelitis, and brainstem syndromes as clinical hallmarks. With a reported prevalence of up to 70%, cognitive impairment is frequent, but often unrecognized and an insufficiently treated burden of the disease. The most common cognitive dysfunctions are decline in attention and memory performance. Magnetic resonance imaging can be used to access structural correlates of neuropsychological disorders. Cognitive impairment is not only a highly underestimated symptom in patients with NMOSD, but potentially also a clinical correlate of attack-independent changes in NMOSD, which are currently under debate. This article reviews cognitive impairment in NMOSD and discusses associations between structural changes of the CNS and cognitive deficits.

[Optical coherence tomography in neuromyelitis optica spectrum disorders]

Neuromyelitis optica spectrum disorders (NMOSD) are mostly relapsing inflammatory conditions of the central nervous system (CNS). In 55% of the cases of NMOSD optic neuritis (ON) is the most frequent first manifestation and can cause severe damage to the afferent visual system and the retina with resultant severe visual impairment. In recent years, investigations of the retina as part of the CNS by optical coherence tomography (OCT) has been shown to be a valid and efficient method for diagnostics and evaluation of the disease course in NMOSD. In addition, OCT not only shows severe damage of the afferent visual system due to multiple bouts of ON but also reveals NMOSD-specific intraretinal pathologies. The latter could be just as important for future differential diagnostics as for the evaluation of potential therapeutic targets. This article briefly reviews the principles of the OCT technique and describes its relevance for the diagnostics and assessment of disease course in NMOSD.

Quantitative 7T MRI does not detect occult brain damage in neuromyelitis optica

Objective

To investigate and compare occult damages in aquaporin-4 (AQP4)-rich periependymal regions in patients with neuromyelitis optica spectrum disorder (NMOSD) vs healthy controls (HCs) and patients with multiple sclerosis (MS) applying quantitative T1 mapping at 7 Tesla (T) in a cross-sectional study.

Methods

Eleven patients with NMOSD (median Expanded Disability Status Scale [EDSS] score 3.5, disease duration 9.3 years, age 43.7 years, and 11 female) seropositive for anti-AQP4 antibodies, 7 patients with MS (median EDSS score 1.5, disease duration 3.6, age 30.2 years, and 4 female), and 10 HCs underwent 7T MRI. The imaging protocol included T2*-weighted (w) imaging and an MP2RAGE sequence yielding 3D T1w images and quantitative T1 maps. We semiautomatically marked the lesion-free periependymal area around the cerebral aqueduct and the lateral, third, and fourth ventricles to finally measure and compare the T1 relaxation time within these areas.

Results

We did not observe any differences in the T1 relaxation time between patients with NMOSD and HCs (all p > 0.05). Contrarily, the T1 relaxation time was longer in patients with MS vs patients with NMOSD (lateral ventricle p = 0.056, third ventricle p = 0.173, fourth ventricle p = 0.016, and cerebral aqueduct p = 0.048) and vs HCs (third ventricle p = 0.027, fourth ventricle p = 0.013, lateral ventricle p = 0.043, and cerebral aqueduct p = 0.005).

Conclusion

Unlike in MS, we did not observe subtle T1 changes in lesion-free periependymal regions in NMOSD, which supports the hypothesis of a rather focal than diffuse brain pathology in NMOSD.

Resting-state functional MRI demonstrates brain network reorganization in neuromyelitis optica spectrum disorder (NMOSD)

BACKGROUND

The relation between brain functional connectivity of patients with neuromyelitis optica spectrum disorder (NMOSD) and the degree of disability remains unclear.

OBJECTIVE

Compare brain functional connectivity of patients with NMOSD to healthy subjects in resting-state functional MRI (rs-fMRI).

METHODS

We compared the rs-fMRI connectivity in 12 NMOSD patients with 20 healthy subjects matched for age and sex. Graph theory analysis was used to quantify the role of each node using a set of metrics: degree, global efficiency, clustering and modularity. To summarize the abnormal connectivity profile of brain regions in patients compared to healthy subjects, we defined a hub disruption index κ.

RESULTS

Concerning the global organization of networks in NMOSD, a small-world topology was preserved without significant modification concerning all average metrics. However, visual networks and the sensorimotor network showed decreased connectivity with high interindividual variability. The hub disruption index κ was correlated to the Expanded Disability Status Scale (EDSS).

CONCLUSION

These results demonstrate a correlation between disability according to the EDSS and neuronal reorganization using the rs-fMRI graph methodology. The conservation of a normal global topological structure despite local modifications in functional connectivity seems to show brain plasticity in response to the disability.

Diagnosis and Treatment of NMO Spectrum Disorder and MOG-Encephalomyelitis

Neuromyelitis optica spectrum disorders (NMOSD) are autoantibody mediated chronic inflammatory diseases. Serum antibodies (Abs) against the aquaporin-4 water channel lead to recurrent attacks of optic neuritis, myelitis and/or brainstem syndromes. In some patients with symptoms of NMOSD, no AQP4-Abs but Abs against myelin-oligodendrocyte-glycoprotein (MOG) are detectable. These clinical syndromes are now frequently referred to as "MOG-encephalomyelitis" (MOG-EM). Here we give an overview on current recommendations concerning diagnosis of NMOSD and MOG-EM. These include antibody and further laboratory testing, MR imaging and optical coherence tomography. We discuss therapeutic options of acute attacks as well as longterm immunosuppressive treatment, including azathioprine, rituximab, and immunoglobulins.

Cross-modal plasticity among sensory networks in neuromyelitis optica spectrum disorders

OBJECTIVE

To explore resting-state (RS) functional connectivity (FC) of the main sensory/motor networks of patients with neuromyelitis optica spectrum disorders (NMOSDs), clinically isolated optic neuritis (ON), and myelitis.

METHODS

Clinical evaluation and RS fMRI were obtained from 28 NMOSD, 11 recurrent ON, and 12 recurrent myelitis patients and 30 healthy controls. Between-group RS FC comparisons and correlations with motor performance were assessed (SPM12) on the main sensory/motor RS networks (RSNs) identified by independent component analysis. Functional network connectivity analysis estimated inter-network connectivity.

RESULTS

Intra- and inter-network RS FCs were reduced in RSNs associated to somatosensory modalities affected by pathology: regions of the primary visual network in ON patients, of the sensorimotor networks in myelitis patients, and of the sensorimotor and secondary visual networks in NMOSD patients. The opposite trend was observed in regions of RSNs spared by pathology: the auditory and part of visual networks in NMOSD, the secondary visual and sensorimotor networks in ON, and the primary visual network in myelitis patients. Better motor performance correlated with higher RS FC of spared RSNs.

CONCLUSION

Sensory and motor RSN abnormalities occur in NMOSD. Loss of function within disease-target networks may elicit cross-modal plasticity across sensory networks potentially preserving clinical function.

Pediatric Multiple Sclerosis: Distinguishing Clinical and MR Imaging Features

This article presents an overview of evolving diagnostic criteria of pediatric multiple sclerosis and related disorders, emphasizing distinguishing clinical and neuroimaging features that should be considered for differential diagnosis in childhood and adolescence. New data on the integrity of brain tissue in children with MS provided by advanced MR imaging techniques are addressed as well.

Value of the central vein sign at 3T to differentiate MS from seropositive NMOSD

Objective

To assess the value of the central vein sign (CVS) on a clinical 3T scanner to distinguish between multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD).

Methods

Eighteen aquaporin-4-antibody-positive patients with NMOSD, 18 patients with relapsing-remitting MS, and 25 healthy controls underwent 3T MRI. The presence of a central vein in white matter lesions on susceptibility-weighted imaging, defined as a thin hypointense line or a small dot, was recorded.

Results

The proportion of lesions with the CVS was higher in MS than NMOSD (80% vs 32%, p < 0.001). A greater proportion of lesions with the CVS predicted the diagnosis of MS, rather than NMOSD (odds ratio 1.10, 95% confidence interval [CI] 1.04 to 1.16, p = 0.001), suggesting that each percent unit increase in the proportion of lesions with the CVS in an individual patient was associated with a 10% increase in the risk of the same patient having MS. If more than 54% of the lesions on any given scan show the CVS, then the patient can be given a diagnosis of MS with an accuracy of 94% (95% CIs 81.34, 99.32, p < 0.001, sensitivity/specificity 90%/100%).

Conclusion

The clinical value of the CVS in the context of the differential diagnosis between MS and NMOSD, previously suggested using 7T scanners, is now extended to clinical 3T scanners, thereby making a step towards the use of CVS in clinical practice.

Classification of evidence

This study provides Class III evidence that the CVS on 3T MRI accurately distinguishes patients with MS from those with seropositive NMOSD.

Optical coherence tomography in neuromyelitis optica spectrum disorders: potential advantages for individualized monitoring of progression and therapy

Neuromyelitis optica spectrum disorders (NMOSD) are mostly relapsing inflammatory disorders of the central nervous system (CNS). Optic neuritis (ON) is the first NMOSD-related clinical event in 55% of the patients, which causes damage to the optic nerve and leads to visual impairment. Retinal optical coherence tomography (OCT) has emerged as a promising method for diagnosis of NMOSD and potential individual monitoring of disease course and severity. OCT not only detects damage to the afferent visual system caused by ON but potentially also NMOSD-specific intraretinal pathology, i.e. astrocytopathy. This article summarizes retinal involvement in NMOSD and reviews OCT methods that could be used now and in the future, for differential diagnosis, for monitoring of disease course, and in clinical trials.

Diagnosis and management of neuromyelitis optica spectrum disorders - An update

Neuromyelitis optica (NMO) and Neuromyelitis optica spectrum disorders (NMOSD) are a group of autoimmune conditions characterized by inflammatory involvement of the optic nerve, spinal cord and central nervous system. Novel evidence showed a key role of autoantibodies against aquaporin-4 immunoglobulin G (AQP4 IgG) in the pathogenesis of NMOSD and, recently, new classification and diagnostic criteria have been adopted to facilitate an earlier identification and improve the management of these conditions. Diagnosis of NMOSD is currently based on clinical, neuroimaging and laboratory features. Standard treatment is based on the use of steroids and immunosuppressive drugs and aims to control the severity of acute attacks and to prevent relapses of the disease. This review gives an update of latest knowledge of NMOSD and NMO, emphasizing the novel diagnostic criteria and both current and future therapeutic approaches.

Diffusion tensor imaging for multilevel assessment of the visual pathway: possibilities for personalized outcome prediction in autoimmune disorders of the central nervous system

The afferent visual pathway represents the most frequently affected white matter pathway in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). Diffusion tensor imaging (DTI) can reveal microstructural or non-overt brain tissue damage and quantify pathological processes. DTI facilitates the reconstruction of major white matter fiber tracts allowing for the assessment of structure-function and damage-dysfunction relationships. In this review, we outline DTI studies investigating the afferent visual pathway in idiopathic optic neuritis (ON), NMOSD, and MS. Since MS damage patterns are believed to depend on multiple factors, i.e., ON (anterior visual pathway damage), inflammatory lesions (posterior visual pathway damage), and global diffuse inflammatory and neurodegenerative processes, comprehensive knowledge on different contributing factors using DTI in vivo may advance our understanding of MS disease pathology. Combination of DTI measures and visual outcome parameters yields the potential to improve routine clinical diagnostic procedures and may further the accuracy of individual prognosis with regard to visual function and personalized disease outcome. However, due to the inherent limitations of DTI acquisition and post-processing techniques and the so far heterogeneous and equivocal data of previous studies, evaluation of the true potential of DTI as a possible biomarker for afferent visual pathway dysfunction is still substantially limited. Further research efforts with larger longitudinal studies and standardized DTI acquisition and post-processing validation criteria are needed to overcome current DTI limitations. DTI evaluation at different levels of the visual pathway has the potential to provide markers for individual damage evaluation in the future. As an imaging biomarker, DTI may support individual outcome prediction during personalized treatment algorithms in MS and other neuroinflammatory diseases, hereby leveraging the concept of predictive, preventive, and personalized medicine in the field of clinical neuroimmunology.

Cervical cord and ventricle affection in neuromyelitis optica

OBJECTIVES

Cervical cord involvement is common in neuromyelitis optica (NMO) and multiple sclerosis (MS), but its impact on disability in NMO has rarely been studied. Recent publications on NMO examined the periventricular system, areas of high aquaporin-4 expression, but not yet by using ventricle volumetry.

PURPOSE

To compare cervical cord atrophy, ventricular widening, and supra- and infratentorial brain measures between NMO and MS, and study their impact on clinical disability.

METHODS

Magnet resonance imaging-based volumetry of upper cervical cord, third and fourth lateral ventricles, grey matter, white matter, brainstem, cerebellum and clinical status of 18 NMO and 20 MS patients, was compared between the groups and with 26 healthy controls. Patterns of ventricular widening relative to healthy controls were inspected by voxel-based morphometry of the cerebrospinal fluid.

RESULTS

Cervical cord atrophy was similar in NMO and MS (75.2 ± 10.0 mm² , respectively, 76.5 ± 9.5 mm² vs 84.1 ± 8.6 mm² in controls).Third ventricle increase in both groups, and specific fourth ventricle widening in MS were detected. Patient groups differed in third to fourth ventricle ratio (P = 0.002). In NMO, white matter correlated inversely with the affected cord segments (P = 0.001) and with cervical cord area (P = 0.043). The disability status was explained by cervical cord area and third ventricle volume (R² =0.524) in NMO, and by grey matter and fourth ventricle volume (R² =0.565) in MS.

CONCLUSION

Cervical cord atrophy and third ventricular enlargement are both clinically relevant in NMO. Third and fourth ventricle volumetry shows differences between NMO and MS regarding the involvement of periventricular structures.

Microstructural visual system changes in AQP4-antibody-seropositive NMOSD

Objective:

To trace microstructural changes in patients with aquaporin-4 antibody (AQP4-ab)-seropositive neuromyelitis optica spectrum disorders (NMOSDs) by investigating the afferent visual system in patients without clinically overt visual symptoms or visual pathway lesions.

Methods:

Of 51 screened patients with NMOSD from a longitudinal observational cohort study, we compared 6 AQP4-ab–seropositive NMOSD patients with longitudinally extensive transverse myelitis (LETM) but no history of optic neuritis (ON) or other bout (NMOSD-LETM) to 19 AQP4-ab–seropositive NMOSD patients with previous ON (NMOSD-ON) and 26 healthy controls (HCs). Foveal thickness (FT), peripapillary retinal nerve fiber layer (pRNFL) thickness, and ganglion cell and inner plexiform layer (GCIPL) thickness were measured with optical coherence tomography (OCT). Microstructural changes in the optic radiation (OR) were investigated using diffusion tensor imaging (DTI). Visual function was determined by high-contrast visual acuity (VA). OCT results were confirmed in a second independent cohort.

Results:

FT was reduced in both patients with NMOSD-LETM (p = 3.52e⁻¹⁴) and NMOSD-ON (p = 1.24e⁻¹⁶) in comparison with HC. Probabilistic tractography showed fractional anisotropy reduction in the OR in patients with NMOSD-LETM (p = 0.046) and NMOSD-ON (p = 1.50e⁻⁵) compared with HC. Only patients with NMOSD-ON but not NMOSD-LETM showed neuroaxonal damage in the form of pRNFL and GCIPL thinning. VA was normal in patients with NMOSD-LETM and was not associated with OCT or DTI parameters.

Conclusions:

Patients with AQP4-ab–seropositive NMOSD without a history of ON have microstructural changes in the afferent visual system. The localization of retinal changes around the Müller-cell rich fovea supports a retinal astrocytopathy.

Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica (NMO) is clinically characterized by severe optic neuritis and transverse myelitis, but recent studies with anti-aquaporin-4-antibody specific to NMO have revealed that the clinical spectrum is wider than previously thought. International consensus diagnostic criteria propose NMO spectrum disorders (NMOSD) as the term to define the entire spectrum including typical NMO, optic neuritis, acute myelitis, brain syndrome, and their combinations. NMOSD is now divided into anti-aquaporin-4-antibody-seropositive NMOSD and -seronegative NMOSD (or unknown serostatus). MR imaging and optical coherence tomography are indispensable in the diagnosis and evaluation of NMOSD. This article reviews the clinical and MR imaging findings of anti-aquaporin-4-antibody-seropositive and anti-myelin oligodendrocyte glycoprotein-antibody-seropositive NMOSD.

Neurodegeneration in multiple sclerosis and neuromyelitis optica

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are autoimmune demyelinating diseases of the central nervous system (CNS), having distinct immunological and pathological features. They have two pathogenic components, 'inflammation' and 'neurodegeneration', with different degrees of severity and pathogenetic mechanisms. The target antigen of autoimmunity in NMO is the water channel aquaporin-4 (AQP4), and antibodies directed against this antigen result in astrocyte damage. MS is a disease primarily affecting myelin and oligodendrocytes, but thus far, no MS-specific autoantigen has been identified. The distinct inflammatory processes in these diseases may trigger cascades of events leading to disease-specific neurodegeneration. Damage of the CNS tissue appears to be amplified by mechanisms that are in part shared by the two conditions and involve oxidative burst activation in microglia/macrophages, mitochondrial damage and axonal energy failure, Wallerian degeneration and meningeal inflammation. However, they appear to differ regarding the nature of the inflammatory response, the type and extent of cortical injury, and the type of astrocyte reaction and damage. Here, we provide a detailed comparison of the pathology between MS and NMO, which may help to define shared and disease-specific mechanisms of neurodegeneration in these diseases.

Complexity and wide range of neuromyelitis optica spectrum disorders: more than typical manifestations

Neuromyelitis optica (NMO), considered to be mediated by autoantibodies, often cause severely disabling disorders of the central nervous system, and predominantly cause optic nerve damage and longitudinally extensive transverse myelitis. Remarkable progress has been made in deciphering NMO pathogenesis during the past decade. In 2015, the International Panel for NMO Diagnosis proposed the unifying term "NMO spectrum disorders" (NMOSD) and the updated NMOSD criteria reflects a wide range of disease and maintains reasonable specificity. Moreover, cumulative findings have indicated that NMOSD are frequently associated with multiple autoimmune diseases, thereby presenting complex clinical symptoms that make this disease more difficult to recognize. Notably, most neurologists do not heed these symptoms or comorbid conditions in patients with NMOSD. Whereas previous reviews have focused on pathogenesis, treatment, and prognosis in NMOSD, we summarize the present knowledge with particular emphasis on atypical manifestations and autoimmune comorbidities in patients with NMOSD. Furthermore, we emphasized the identification of these atypical characteristics to enable a broader and better understanding of NMOSD, and improve early accurate diagnosis and therapeutic decision making.

The use of targeted genomic capture and massively parallel sequencing in diagnosis of Chinese Leukoencephalopathies

Leukoencephalopathies are diseases with high clinical heterogeneity. In clinical work, it’s difficult for doctors to make a definite etiological diagnosis. Here, we designed a custom probe library which contains the known pathogenic genes reported to be associated with Leukoencephalopathies, and performed targeted gene capture and massively parallel sequencing (MPS) among 49 Chinese patients who has white matter damage as the main imaging changes, and made the validation by Sanger sequencing for the probands’ parents. As result, a total of 40.8% (20/49) of the patients identified pathogenic mutations, including four associated with metachromatic leukodystrophy, three associated with vanishing white matter leukoencephalopathy, three associated with mitochondrial complex I deficiency, one associated with Globoid cell leukodystrophy (or Krabbe diseases), three associated with megalencephalic leukoencephalopathy with subcortical cysts, two associated with Pelizaeus-Merzbacher disease, two associated with X-linked adrenoleukodystrophy, one associated with Zellweger syndrome and one associated with Alexander disease. Targeted capture and MPS enables to identify mutations of all classes causing leukoencephalopathy. Our study combines targeted capture and MPS technology with clinical and genetic diagnosis and highlights its usefulness for rapid and comprehensive genetic testing in the clinical setting. This method will also expand our knowledge of the genetic and clinical spectra of leukoencephalopathy.

Comparison of myelin water fraction values in periventricular white matter lesions between multiple sclerosis and neuromyelitis optica spectrum disorder

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are inflammatory autoimmune diseases of the central nervous system. We hypothesized that the degree of demyelination within lesions in MS and NMOSD would differ as the pathophysiology of the two diseases do. We used myelin water imaging to compare the myelin water fraction (MWF) in 106 periventricular white matter (PVWM) lesions in 27 MS patients and 51 PVWM lesions in 20 NMOSD patients. The MWF was significantly reduced in the MS compared with the NMOSD lesions, suggesting that myelin loss was more severe in MS than in NMOSD.

Electrodynamics and radiofrequency antenna concepts for human magnetic resonance at 23.5 T (1 GHz) and beyond

OBJECTIVE

This work investigates electrodynamic constraints, explores RF antenna concepts and examines the transmission fields (B 1 (+) ) and RF power deposition of dipole antenna arrays for (1)H magnetic resonance of the human brain at 1 GHz (23.5 T).

MATERIALS AND METHODS

Electromagnetic field (EMF) simulations are performed in phantoms with average tissue simulants for dipole antennae using discrete frequencies [300 MHz (7.0 T) to 3 GHz (70.0 T)]. To advance to a human setup EMF simulations are conducted in anatomical human voxel models of the human head using a 20-element dipole array operating at 1 GHz.

RESULTS

Our results demonstrate that transmission fields suitable for (1)H MR of the human brain can be achieved at 1 GHz. An increase in transmit channel density around the human head helps to enhance B 1 (+) in the center of the brain. The calculated relative increase in specific absorption rate at 23.5 versus 7.0 T was below 1.4 (in-phase phase setting) and 2.7 (circular polarized phase setting) for the dipole antennae array.

CONCLUSION

The benefits of multi-channel dipole antennae at higher frequencies render MR at 23.5 T feasible from an electrodynamic standpoint. This very preliminary finding opens the door on further explorations that might be catalyzed into a 20-T class human MR system.

Neuromyelitis optica does not impact periventricular venous density versus healthy controls: a 7.0 Tesla MRI clinical study

OBJECTIVE

To quantify the periventricular venous density in neuromyelitis optica spectrum disease (NMOSD) in comparison to that in patients with multiple sclerosis (MS) and healthy control subjects.

MATERIALS AND METHODS

Sixteen patients with NMOSD, 16 patients with MS and 16 healthy control subjects underwent 7.0-Tesla (7T) MRI. The imaging protocol included T2*-weighted (T2*w) fast low angle-shot (FLASH) and fluid-attenuated inversion recovery (FLAIR) sequences. The periventricular venous area (PVA) was manually determined by a blinded investigator in order to estimate the periventricular venous density in a region of interest-based approach.

RESULTS

No significant differences in periventricular venous density indicated by PVA were detectable in NMOSD versus healthy controls (p = 0.226). In contrast, PVA was significantly reduced in MS patients compared to healthy controls (p = 0.013).

CONCLUSION

Unlike patients with MS, those suffering from NMOSD did not show reduced venous visibility. This finding may underscore primary and secondary pathophysiological differences between these two distinct diseases of the central nervous system.