Gyroscan nt 1

All MRI scans were performed on a 1.5 Tesla magnet (Philips Gyroscan NT 15, Netherlands) at baseline, month 12 and month 24. The MRI protocol included proton density-and T2-weighted spin echo images (TR 2000 ms, TE 20/90 ms, matrix size 256×256, field of view 24 cm×24 cm, slice thickness 3 mm, gap 0 mm, 48 axial slices) and T1-weighted images (TR 600 ms, TE 15 ms, matrix size 256×256, field of view 24 cm x 24 cm, slice thickness 3 mm, gap 0, 48 axial slices) obtained before and five minutes after an intravenous injection of 0,1 mmol/kg of gadoliniumdiethylenetriamine penta-acetic acid (Gd).
Volumes of hyperintense lesions on T2-weighted images (T2-LL), hypointense lesions on T1weighted post-contrast images (T1-LL) and hyperintense lesions on T1-weighted post-contrast images (T1-Gd-LL) were quantified using a semi-automated method (Jim 4.0, Xinapse System, Leicester, UK). The number of patients with Gd-enhancing lesions at baseline and at month 24 was calculated for each group. The cumulative number of combined unique active (CUA) lesions, defined as new Gd enhancing lesions or new T2-weighted lesions (non-enhancing on post-contrast T1-weighted acquisitions, in order to avoid double-counting), was also quantified at month 24.