Learning Myelin Content in Multiple Sclerosis from Multimodal MRI through Adversarial Training

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS). A reliable measure of the tissue myelin content is therefore essential for the understanding of the physiopathology of MS, tracking progression and assessing treatment efficacy. Positron emission tomography (PET) with [^{11} \mbox{C}] \mbox{PIB} has been proposed as a promising biomarker for measuring myelin content changes in-vivo in MS. However, PET imaging is expensive and invasive due to the injection of a radioactive tracer. On the contrary, magnetic resonance imaging (MRI) is a non-invasive, widely available technique, but existing MRI sequences do not provide, to date, a reliable, specific, or direct marker of either demyelination or remyelination. In this work, we therefore propose Sketcher-Refiner Generative Adversarial Networks (GANs) with specifically designed adversarial loss functions to predict the PET-derived myelin content map from a combination of MRI modalities. The prediction problem is solved by a sketch-refinement process in which the sketcher generates the preliminary anatomical and physiological information and the refiner refines and generates images reflecting the tissue myelin content in the human brain. We evaluated the ability of our method to predict myelin content at both global and voxel-wise levels. The evaluation results show that the demyelination in lesion regions and myelin content in normal-appearing white matter (NAWM) can be well predicted by our method. The method has the potential to become a useful tool for clinical management of patients with MS.Comment: Accepted by MICCAI201

HLA-DRB1*15 influences the development of brain tissue damage in early PPMS

OBJECTIVES To investigate whether (1) there were differences between HLA-DRB1*15-positive and -negative patients at baseline, and (2) HLA-DRB1*15-positive patients showed a greater development of brain and spinal cord damage, as assessed by MRI, and greater progression of disability, during a 5-year follow-up, compared with HLA-DRB1*15-negative patients. METHODS HLA-DRB1*15 typing was performed in 41 patients with primary progressive multiple sclerosis (PPMS) who were recruited within 5 years of symptom onset. All patients and 18 healthy controls were studied clinically and with MRI at baseline, and every 6 months for 3 years, and then at 5 years. Magnetization transfer ratio parameters and volumes for brain gray matter and normal-appearing white matter, brain T2 lesion load, and spinal cord cross-sectional area were obtained. Patient disability was assessed at each visit using the Expanded Disability Status Scale and Multiple Sclerosis Functional Composite subscores. RESULTS There were no significant differences between HLA-DRB1*15-positive and -negative patients at baseline. HLA-DRB1*15-positive patients showed a greater decline in brain magnetization transfer ratio for gray matter and normal-appearing white matter (both p = 0.005) than HLA-DRB1*15-negative patients over 5 years, while the same parameters did not change over time in healthy controls. HLA-DRB1*15-positive patients also showed a trend toward a faster increase in brain T2 lesion load than HLA-DRB1*15-negative patients (0.29 [95% confidence interval 0.20-0.38] vs 0.21 [0.13-0.30] mL/mo, p = 0.085) and higher T2 lesion volumes at all time points (average difference [95% confidence interval]: 10.58 mL [7.09-14.07], p < 0.001) during the follow-up, after adjusting for disease duration. CONCLUSIONS These findings suggest that HLA-DRB1*15 influences the progression of brain pathology in PPMS

Imaging Characteristics of Choroid Plexuses in Presymptomatic Multiple Sclerosis. A Retrospective Study

Background and Objectives Recent imaging studies have suggested a possible involvement of the choroid plexus (CP) in multiple sclerosis (MS). Here, we investigated whether CP changes are already detectable at the earliest stage of MS, preceding symptom onset. Methods This study is a retrospective analysis of 27 patients with presymptomatic MS, 97 patients with clinically definite MS (CDMS), and 53 healthy controls (HCs) who underwent a cross-sectional 3T-MRI acquisition; of which, 22 MS, 19 HCs, and 1 presymptomatic MS (evaluated 8 months before conversion to CDMS) also underwent translocator protein (TSPO) F-18-DPA-714 PET and were included in the analysis. CPs were manually segmented on 3D T1-weighted images for volumetric analysis. CP F-18-DPA-714 uptake, reflecting inflammation, was calculated as the average standardized uptake value (SUV). Multivariable regressions adjusted for age, sex, and ventricular and brain volume were fitted to test CP volume differences between presymptomatic patients and MS or HCs. For the presymptomatic case who also had F-18-DPA-714 PET, CP SUV differences with MS and HCs were assessed through Crawford-Howell tests. To provide further insight into the interpretation of F-18-DPA-714-PET uptake at the CP level, a postmortem analysis of CPs in MS vs HCs was performed to characterize the cellular localization of TSPO expression. Results Compared with HCs, patients with presymptomatic MS had 32% larger CPs (beta = 0.38, p = 0.001), which were not dissimilar to MS CPs (p = 0.69). Moreover, in the baseline scan of the presymptomatic case who later on developed MS, TSPO PET showed 33% greater CP inflammation vs HCs (p = 0.04), although no differences in F-18-DPA-714 uptake were found in parenchymal regions vs controls. CP postmortem analysis identified a population of CD163(+) mononuclear phagocytes expressing TSPO in MS, possibly contributing to the increased F-18-DPA-714 uptake. Discussion We identified an imaging signature in CPs at the presymptomatic MS stage using MRI; in addition, we found an increased CP inflammation with PET in a single presymptomatic patient. These findings suggest a role of CP imaging as an early biomarker and argue for the involvement of the blood-CSF barrier dysfunction in disease development

Problems and Pitfalls of Identifying Remyelination in Multiple Sclerosis.

Regenerative medicines that promote remyelination in multiple sclerosis (MS) are making the transition from laboratory to clinical trials. While animal models provide the experimental flexibility to analyze mechanisms of remyelination, here we discuss the challenges in understanding where and how remyelination occurs in MS.The authors acknowledge the following support: The UK Multiple Sclerosis Society (RTK, CZ, RJMF), The Adelson Medical Research Foundation (DSR, DEB, RJMF), Intramural Research Program of NINDS/NIH (DSR), European Research Council (ERC) under the European Union Horizon 2020 Re- search and Innovation Program (RTK), The Lister Institute (RTK), and a core support grant from the Wellcome and MRC to the Wellcome-Medical Research Council Cambridge Stem Cell Institute (RTK, RJMF)

Problems and Pitfalls of Identifying Remyelination in Multiple Sclerosis

The authors acknowledge the following support: The UK Multiple Sclerosis Society (MS50 to R.T.K., C.Z., and R.J.M.F.), The Adelson Medical Research Foundation (D.S.R., D.E.B., and R.J.M.F.), Intramural Research Program of NINDS/NIH (D.S.R.), European Research Council (ERC) under the European Union Horizon 2020 Research and Innovation Program (771411 to R.T.K.), The Lister Institute (R.T.K.), and a core support grant from the Wellcome and MRC to the Wellcome-Medical Research Council Cambridge Stem Cell Institute (203151/Z/16/Z to R.T.K. and R.J.M.F.). Publisher Copyright: © 2020 Elsevier Inc.Regenerative medicines that promote remyelination in multiple sclerosis (MS) are making the transition from laboratory to clinical trials. While animal models provide the experimental flexibility to analyze mechanisms of remyelination, here we discuss the challenges in understanding where and how remyelination occurs in MS.Peer reviewe

Smouldering multiple sclerosis: the 'real MS'

Using a philosophical approach or deductive reasoning, we challenge the dominant clinico-radiological worldview that defines multiple sclerosis (MS) as a focal inflammatory disease of the central nervous system (CNS). We provide a range of evidence to argue that the 'real MS' is in fact driven primarily by a smouldering pathological disease process. In natural history studies and clinical trials, relapses and focal activity revealed by magnetic resonance imaging (MRI) in MS patients on placebo or on disease-modifying therapies (DMTs) were found to be poor predictors of long-term disease evolution and were dissociated from disability outcomes. In addition, the progressive accumulation of disability in MS can occur independently of relapse activity from early in the disease course. This scenario is underpinned by a more diffuse smouldering pathological process that may affect the entire CNS. Many putative pathological drivers of smouldering MS can be potentially modified by specific therapeutic strategies, an approach that may have major implications for the management of MS patients. We hypothesise that therapeutically targeting a state of 'no evident inflammatory disease activity' (NEIDA) cannot sufficiently prevent disability accumulation in MS, meaning that treatment should also focus on other brain and spinal cord pathological processes contributing to the slow loss of neurological function. This should also be complemented with a holistic approach to the management of other systemic disease processes that have been shown to worsen MS outcomes

A plea for equitable global access to COVID‐19 diagnostics, vaccination and therapy: The NeuroCOVID‐19 Task Force of the European Academy of Neurology

Coronavirus disease 2019 (COVID‐19), a multi‐organ disease caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), continues to challenge health and care systems around the globe. The pandemic has disrupted acute neurology services and routine patient care and has impacted the clinical course in patients with chronic neurological disease. COVID‐19 appears to have exposed inequalities of societies and healthcare systems and had a disproportionate impact on already vulnerable communities. The next challenge will be to set up initiatives to stop disparities in all aspects related to COVID‐19. From the medical perspective, there is a need to consider inequalities in prevention, treatment and long‐term consequences. Some of the issues of direct relevance to neurologists are summarised. With this appraisal, the European Academy of Neurology NeuroCOVID‐19 Task Force intends to raise awareness of the potential impact of COVID‐19 on inequalities in healthcare and calls for action to prevent disparity at individual, national and supranational levels

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR&nbsp;=&nbsp;2.05, 95%CI&nbsp;=&nbsp;1.39–3.02, p&nbsp;&lt;&nbsp;0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR&nbsp;=&nbsp;0.42, 95%CI&nbsp;=&nbsp;0.18–0.99, p&nbsp;=&nbsp;0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon