Andorra M, et al. - Researchers sought to assess the dynamics of brain volume loss (BVL) in correlation with multiple sclerosis progression, and if a volume loss of less than 0.4% per year is an accurate marker of therapeutic response. In addition, they examined the repeatability and exchangeability of BVL estimates with Jacobian Integration and Functional Magnetic Resonance Imaging of the Brain Software Library (specifically, the Structural Image Evaluation, Using Normalisation, of Atrophy–Cross-Sectional tool or FMRIB’s Integrated Registration and Segmentation Tool). Findings reveal faster brain volume loss in the first 5 years after multiple sclerosis onset, which affects the usability of a 0.4% threshold. Considering an expected loss of 0.5% to 1.35% per year, they noted poor repeatability of 2 separate imaging methods that restricts their use at the individual level. In addition, the 2 approaches differed regarding volumetric estimates and the accuracy of thresholds to discriminate patients with multiple sclerosis from healthy volunteers. They recommend further clarification before promoting brain volume loss as a marker of therapeutic response in multiple sclerosis.