Single MRI-Based Volumetric Assessment in Clinical Practice Is Associated With MS-Related Disability

Background The added value of brain volume measurements in the clinical practice of multiple sclerosis (MS) has been questioned. Purpose To investigate the contribution of volume measures obtained with magnetic resonance scans performed as part of regular care to predict measures of cognitive and physical MS disability in a real-world setting. Study Type Retrospective. Subjects In all, 470 adults with diagnosed MS. Field Strength/Sequence 3D fluid attenuation inversion recovery (FLAIR) and 3D T-1-weighted MR images at 3.0T MR. Assessment Lesion and brain volume were measured by an automated method, MSmetrix, developed by icometrix. Statistical Tests We used stepwise linear regression models to assess the added value of a single volumetric assessment in predicting Expanded Disability Status Scale (EDSS) and Symbol Digit Modalities Test (SDMT). Brain volumes categorized into quartiles were used as predictive variables in a time-to-event analysis and Cox proportional hazard regression with time to worsening from baseline as outcome measures. Results Brain and lesion volume in relapsing onset MS strongly contributed to the best models, with a substantial role for age in the EDSS model and a modest role for education in the SDMT model. Adding MR volumetric information increased the explained variance from 17% to 28% in the best model for EDSS and from 9% to 25% in the best model for SDMT. A significantly reduced hazard (P < 0.05) of SDMT worsening was found in the highest normalized brain volume quartiles (1375-1608 ml), compared with the lowest quartile (1201-1374 ml) in the total study population. Data Conclusion Our findings indicate that a single brain volumetric assessment contributes to the prediction of MS-related disability, with distinct patterns for EDSS as a measure of physical disability, and SDMT as a measure of cognitive disability. A threshold effect for the lowest brain volumes with regard to SDMT worsening over time was found.