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

Abstract

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 T₁ -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.

Level of evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1312-1321.

Keywords: brain volume; cognitive disability; lesion volume; multiple sclerosis; physical disability.