Statistical analysis

All data were carried out by using SPSS version 21.0 software (SPSS Inc., Chicago, IL, USA). The permeability, perfusion, and histogram parameters of the lesions and NAWM regions did not conform to the normal distribution by using one-sample Kolmogorov–Smirnov test. The median (P25–P75) was used to describe these parameters. We compared the median of the K^trans, V_p, CBF, and CBV between groups by using Kruskal–Wallis H rank-sum test and Nemenyi test in SAS 9.2 software. We compared the skewness and kurtosis of MS lesions using Kruskal–Wallis H rank-sum test. Spearman’s correlation was used to test the association of imaging biomarkers with EDSS scores and disease duration. P<0.05 was considered to indicate statistical significance.