Tract-based χ-separation imaging differentiates multiple sclerosis from neuromyelitis optica spectrum disorder by mapping iron and myelin signatures

作者：Shaolong Wu, Y D Xie, Yu Zhang, Yan Su, Hongquan Zhu, Bingfang Duan, Alexey Dimov, Wenzhen Zhu, Yi Wang · 发表于：BMC Medical Imaging · 年份：2026 · DOI：10.1186/s12880-026-02537-3 · 研究领域：Multiple Sclerosis Research Studies、Advanced Neuroimaging Techniques and Applications、Advanced MRI Techniques and Applications

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) frequently present with overlapping clinical and radiological features, complicating differential diagnosis. Iron and myelin abnormalities are central to their pathophysiology, yet their distinct contributions in vivo remain poorly characterized. This study applied tract-based χ-separation imaging to evaluate susceptibility-related microstructural changes in normal-appearing white matter (NAWM) and lesions in MS and NMOSD, aiming to identify imaging patterns between these demyelinating diseases. Eighty patients (48 MS, 32 AQP4-IgG-positive NMOSD) and 39 healthy controls were included. Quantitative susceptibility mapping (QSM) with χ-separation was performed on a 3D multi-echo gradient-echo sequence to obtain bulk susceptibility and to derive model-based positive susceptibility (χ pos ) and negative susceptibility (χ neg) sources. After masking lesions, mean values of susceptibility, χ pos and χ neg were extracted from 20 JHU white matter tracts, and lesions were compared with tract-matched NAWM within each disease group. Key features were identified using LASSO with cross-validation, and receiver operating characteristic (ROC) analysis was used to assess discrimination between MS and NMOSD. The three groups were similar in age and sex distribution. Mean disease duration was 4.12 ± 4.58 years in MS and 3.61 ± 4.26 years in NMOSD. Compared with NMOSD, MS showed reduced χ pos in 12 NAWM tracts and increas...