Monitoring Remyelination and Its Association With Disability Improvement in Multiple Sclerosis Using APART‐QSM: A Longitudinal Cohort Study
Zhuo Wang, Mingsong Tang, Junye Yao, Kai Ai, Yujing Li, Jun Wang, Xia Xu, Wenjing Ren, Wenzhu Dang, Guangyao Liu, Yanli Jiang, Siru Kang, Wenxia Yang, Hao Li, Dan Yang, Yuping Han, Jinrui Liu, Fei Jia, Jingqi Jiang, Yucheng Ding, Jing ZhangABSTRACT
Background
Conventional MRI has limited specificity for myelin quantification. IterAtive magnetic suscePtibility sources sepARaTion quantitative susceptibility mapping (APART–QSM) quantifies myelin–sensitive (χ dia ) and iron–sensitive (χ para ) susceptibility components, but its value for longitudinal assessment of remyelination in multiple sclerosis (MS) remains unclear.
Purpose
To characterize longitudinal χ dia in MS and assess its associations with clinical characteristics.
Study Type
Prospective, longitudinal.
Population
One hundred forty–five patients with MS and 65 healthy controls (HCs).
Field Strength/Sequence
3.0T;
Assessment
APART‐QSM generated χ dia and χ para maps, with susceptibility quantified in lesions and non–lesional regions, and the Expanded Disability Status Scale (EDSS) assessed at baseline and follow–up.
Statistical Tests
Chi–square, Mann–Whitney U, Wilcoxon signed–rank, Friedman tests, linear mixed‐effects models, linear and nonlinear regression. A p value < 0.05 was considered significant.
Results
One hundred one patients with MS and 20 HCs completed follow–up after a median (IQR) interval of 1.0 (0.8) and 1.25 (0.2) years, respectively. At baseline, white matter lesions (WMLs) exhibited lower χ dia (0.0131 [IQR 0.0087] ppm) and higher χ para (0.0058 [IQR 0.0049] ppm) than corresponding normal‐appearing white matter (NAWM) (0.0191 [0.0088] ppm; 0.0036 [0.0038] ppm; both p < 0.001). Over 1 year, χ dia in WMLs increased (0.0122 [IQR 0.0069] vs. 0.0152 [IQR 0.0065] ppm, p < 0.001), particularly in ofatumumab‐treated patients (0.0114 [IQR 0.0085] vs. 0.0158 [IQR 0.0081] ppm, p < 0.001). Greater increases in χ dia were significantly associated with female sex, ofatumumab treatment, relapsing–remitting phenotype, and EDSS improvement (all Bonferroni correction p < 0.01). Δχ dia showed a nonlinear decline with increasing disease duration (effective degrees of freedom ( edf ) = 1.83, p = 0.002).
Conclusion
APART–QSM may enable longitudinal monitoring of remyelination–related changes in MS, with declining Δχ dia over disease duration potentially informing individualized treatment strategies.
Level of Evidence
2.
Stage of Technical Efficacy
2.