Sample sizes for brain atrophy outcomes in trials for secondary progressive multiple sclerosis

Altmann, Dr; Jasperse, B; Barkhof, F; Beckmann, K; Filippi, Massimo; Kappos, Ld; Molyneux, P; Polman, Ch; Pozzilli, C; Thompson, Aj; Wagner, K; Yousry, Ta; Miller, Dh