The diffusion properties from diffusion tensor imaging (DTI) are sensitive to white matter (WM) abnormalities and could serve as indicators of diffuse axonal damages incurred during a traumatic brain injury (TBI). Analyses of diffusion metrics in the regions of interest (ROIs) were used to compare the differences in the 18 major fiber tracts in 46 participants, between TBI participants with (n = 17) or without (n = 16) chronic symptoms (CS) and a control group (CG, n = 13). In addition to the widely used diffusion metrics, such as fractional anisotropy (FA), mean (MD), axial (AD) and radial (RD) diffusivities, apparent fiber density (AFD), complexity (CX) and fixel number (FN) derived from Mrtrix3 software package were used to characterize WM tracts and compare between participant groups in the ROIs defined by the fixel numbers. Significant differences were found in FA, AFD, MD, RD and CX in ROIs with different FNs in the corpus callosum forceps minor, left and right inferior longitudinal fasciculus, and left and right uncinate fasciculus for both TBI groups compared to controls. Diffusion properties in ROIs with different FNs can serve as detailed biomarkers of WM abnormalities, especially for individuals with chronic TBI related symptoms.

弥散张量成像 (DTI) 的弥散特性对白质 (WM) 异常敏感，可作为外伤性脑损伤期间弥散性轴突损伤的指标（脑外伤）。感兴趣区域 (ROI) 中的扩散指标分析用于比较 46 名参与者的 18 条主要纤维束的差异，TBI 参与者有 (n = 17) 或没有 (n = 16) 慢性症状 (CS) 和对照组（CG，n = 13）。除了广泛使用的扩散指标，例如分数各向异性 (FA)、平均 (MD)、轴向 (AD) 和径向 (RD) 扩散率、表观纤维密度 (AFD)、复杂性 (CX) 和固定像素数 (FN)从 Mrtrix3 软件包派生的用于描述 WM 区域的特征，并比较由 fixel 编号定义的 ROI 中的参与者组。胼胝体钳小、左、右下纵束中不同FN的ROI中FA、AFD、MD、RD和CX均有显着差异，以及与对照组相比，两个 TBI 组的左右钩束。具有不同 FN 的 ROI 中的扩散特性可以作为 WM 异常的详细生物标志物，特别是对于具有慢性 TBI 相关症状的个体。