MRI-based Brain Volumetric Analysis Protocol

All MRI scans were performed with a standardized protocol at a central site on the same 1.5 T scanner (Gyroscan; Philips Medical Systems, Best, The Netherlands). The MRI scans were performed at least 30 days after intravenous high dose steroids and not more than 120 days after or before their respective spinal tap (Figure 2). Axial brain acquisitions included fluid attenuated inversion recovery (FLAIR) and 3D T1-weighted images (3D-T1W). Image analyses included the analyses of changes in T2 lesions and whole brain volumes. Absolute T2 lesion volumes and brain parenchymal fractions were obtained using ScanView software [24 (link)] and percent changes in whole brain (WB) volumes were obtained using the SIENA method [25 (link),26 (link)]. Lesion filling on 3D T1-WI images was used to reduce the impact of T1 hypo-intensities on tissue segmentation [27 (link)].