Objective Rates of worsening and evolution to secondary progressive multiple sclerosis (MS) may be substantially lower in actively treated patients compared to natural history studies from the pretreatment era. Nonetheless, in our recently reported prospective cohort, more than half of patients with relapsing MS accumulated significant new disability by the 10th year of follow‐up. Notably, “no evidence of disease activity” at 2 years did not predict long‐term stability. Here, we determined to what extent clinical relapses and radiographic evidence of disease activity contribute to long‐term disability accumulation. Methods Disability progression was defined as an increase in Expanded Disability Status Scale (EDSS) of 1.5, 1.0, or 0.5 (or greater) from baseline EDSS = 0, 1.0–5.0, and 5.5 or higher, respectively, assessed from baseline to year 5 (±1 year) and sustained to year 10 (±1 year). Longitudinal analysis of relative brain volume loss used a linear mixed model with sex, age, disease duration, and HLA‐DRB1*15:01 as covariates. Results Relapses were associated with a transient increase in disability over 1‐year intervals ( p = 0.012) but not with confirmed disability progression ( p = 0.551). Relative brain volume declined at a greater rate among individuals with disability progression compared to those who remained stable ( p < 0.05). Interpretation Long‐term worsening is common in relapsing MS patients, is largely independent of relapse activity, and is associated with accelerated brain atrophy. We propose the term silent progression to describe the insidious disability that accrues in many patients who satisfy traditional criteria for relapsing–remitting MS. Ann Neurol 2019;85:653–666

Objective In multiple sclerosis (MS) cerebral gray matter (GM) atrophy correlates more strongly than white matter (WM) atrophy with disability. The corresponding relationships in the spinal cord (SC) are unknown due to technical limitations in assessing SCGM atrophy. Using phase sensitive inversion recovery (PSIR) MRI, we determined the association of the SCGM and SCWM areas with MS disability and disease type. Methods 113 MS patients and 20 healthy controls were examined at 3T with a PSIR sequence acquired at the C2/C3 disc level. Two independent, clinically-masked readers measured the cord WM and GM areas. Correlations between cord areas and Expanded Disability Status Score (EDSS) were determined. Differences in areas between groups were assessed with age and sex as covariates. Results Relapsing (R) MS patients showed smaller SCGM areas than age and sex matched controls (p=0.008) without significant differences in SCWM areas. Progressive MS patients showed smaller SCGM and SCWM areas compared to RMS patients (all p≤0.004). SCGM, SCWM, and whole cord areas inversely correlated with EDSS (rho: −0.60, −0.32, −0.42, respectively; all p≤0.001). SCGM area was the strongest correlate of disability in multivariate models including brain GM and WM volumes, FLAIR lesion load, T1-lesion load, SCWM area, number of spinal cord T2 lesions, age, sex, disease duration. Brain and spinal GM independently contributed to EDSS. Interpretation SCGM atrophy is detectable in-vivo in absence of WM atrophy in RMS. It is more pronounced in progressive than RMS and contributes more to patient disability than spinal cord WM or brain GM atrophy.

Background and Purpose-The quantification of spinal cord (SC) atrophy by MRI has assumed an important role in assessment of neuroinflammatory/neurodegenerative diseases and traumatic SC injury. Recent technical advances make possible the quantification of gray matter (GM) and white matter tissues in clinical settings. However, the goal of a reliable diagnostic, prognostic or predictive marker is still elusive, in part due to large inter-subject variability of SC areas. Here, we investigated the sources of this variability and explored effective strategies to reduce it.Methods-129 healthy subjects (mean age: 41.0±15.9) underwent MRI on a Siemens 3T Skyra scanner. 2D PSIR at the C2-C3 vertebral level and a sagittal 1mm 3 3D T1-weighted brain acquisition extended to the upper cervical cord were acquired. Total cross-sectional area and GM area were measured at C2-C3, as well as measures of the vertebra, spinal canal and the skull. Correlations between the different metrics were explored using Pearson product-moment coefficients. The most promising metrics were used to normalize cord areas using multiple regression analyses.Results-The most effective normalization metrics were the V-scale (from SienaX) and the product of the C2-C3 spinal canal diameters. Normalization methods based on these metrics reduced the inter-subject variability of cord areas of up to 17.74%. The measured cord areas had a statistically significant sex difference, while the effect of age was moderate.Conclusions-The present work explored in a large cohort of healthy subjects the source of inter-subject variability of SC areas and proposes effective normalization methods for its reduction.

Background and Objectives Magnetic resonance imaging (MRI) can be used to measure structural changes in the brain of people with multiple sclerosis (MS), and is essential for diagnosis, longitudinal monitoring, and therapy evaluation. The North American Imaging in Multiple Sclerosis Cooperative (NAIMS) steering committee developed a uniform high-resolution 3T MRI protocol relevant to the quantification of cerebral lesions and atrophy and implemented it at seven sites across the United States. To assess inter-site variability in scan data, a volunteer with relapsing-remitting MS was imaged with a scan-rescan at each site. Materials and Methods All imaging was acquired on Siemens scanners (4 Skyra, 2 TIM Trio, and 1 Verio). Expert segmentations were manually obtained for T1-hypointense and T2 (FLAIR)-hyperintense lesions. Several automated lesion detection and whole-brain, cortical, and deep gray matter volumetric pipelines were applied. Statistical analyses were conducted to assess variability across sites, as well as systematic biases in the volumetric measurements that were site-related. Results Systematic biases due to site differences in expert-traced lesion measurements were significant (p<0.01 for both T1 and T2 lesion volumes), with site explaining over 90% of the variation (range = 13.0–16.4ml in T1 and 15.9–20.1ml in T2) in lesion volumes. Site also explained more than 80% of the variation in most automated volumetric measurements. Output measures clustered according to scanner models, with similar results from the Skyra vs. the other two units. Conclusions Even in multi-center studies with consistent scanner field strength and manufacturer, after protocol harmonization, systematic differences can lead to severe biases in volumetric analyses.

The source of inter-subject variability and the influence of age and gender on morphometric characteristics of the spinal cord, such as the total cross-sectional area (TCA), the gray matter (GM) and white matter (WM) areas, currently remain under investigation. Understanding the effect of covariates such as age, gender, brain volumes, and skull- and vertebra-derived metrics on cervical and thoracic spinal cord TCA and GM areas in healthy subjects would be fundamental for exploring compartment specific changes in neurological diseases affecting the spinal cord. Using Magnetic Resonance Imaging at 3T we investigated 32 healthy subjects using a 2D phase sensitive inversion recovery sequence and we measured TCA, GM and WM areas at 4 cervical and thoracic levels of the spinal cord. We assessed age and gender relationships of cord measures and explored associations between cord measures and a) brain volumes and b) skull- and vertebra-derived metrics. Age and gender had a significant effect on TCA, WM and GM areas (with women and elderly having smaller values than men and younger people respectively), but not on the GM area/TCA ratio. The total intracranial volume and C3 vertebra dimensions showed the highest correlations with cord measures. When used in multi-regression models, they reduced cord areas group variability by approximately a third. Age and gender influences on cord measures and normalization strategies here presented might be of use in the study of compartment specific changes in various neurological diseases affecting the spinal cord.