As the different analyses included different muscle subgroups (all 12 muscles for ROEM analyses, ten muscles for a cross-sectional area, eight muscles for T2 measurement) when overall means were calculated only the common set of muscles were included, left and right: SR, IR, LR and MR. Mean values in patient and control groups, reported with their respective standard deviations, were compared using the two-tailed Student’s t-test. The proportion of muscles in each group with T1w hyperintensity was compared with Pearson’s χ2 test. Correlations between MRI measures were analysed using the Spearman rank correlation (rho). All statistical analyses were performed using IBM SPSS Version 20.