Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan.
Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang-Gung University, Taoyuan, Taiwan.
Eur Radiol Exp. 2024 Jul 24;8(1):82. doi: 10.1186/s41747-024-00490-w.
This study aimed to investigate the long-term effects of repetitive mild traumatic brain injury (rmTBI) with varying inter-injury intervals by measuring diffusion tensor metrics, including mean diffusivity (MD), fractional anisotropy (FA), and diffusion magnitude (L) and pure anisotropy (q).
Eighteen rats were randomly divided into three groups: short-interval rmTBI (n = 6), long-interval rmTBI (n = 6), and sham controls (n = 6). MD, FA, L, and q values were analyzed from longitudinal diffusion tensor imaging at days 50 and 90 after rmTBI. Immunohistochemical staining against neurons, astrocytes, microglia, and myelin was performed. Analysis of variance, Pearson correlation coefficient, and simple linear regression model were used.
At day 50 post-rmTBI, lower cortical FA and q values were shown in the short-interval group (p ≤ 0.038). In contrast, higher FA and q values were shown for the long-interval group (p ≤ 0.039) in the corpus callosum. In the ipsilesional external capsule and internal capsule, no significant changes were found in FA, while lower L and q values were shown in the short-interval group (p ≤ 0.028) at day 90. The q values in the external capsule and internal capsule were negatively correlated with the number of microglial cells and the total number of astroglial cells (p ≤ 0.035).
Tensor scalar measurements, such as L and q values, are sensitive to exacerbated chronic injury induced by rmTBI with shorter inter-injury intervals and reflect long-term astrogliosis induced by the cumulative injury.
Tensor scalar measurements, including L and q values, are potential DTI metrics for detecting long-term and subtle injury following rmTBI; in particular, q values may be used for quantifying remote white matter (WM) changes following rmTBI.
The alteration of L and q values was demonstrated after chronic repetitive mild traumatic brain injury. Changing q values were observed in the impact site and remote WM. The lower q values in the remote WM were associated with astrogliosis.
本研究旨在通过测量扩散张量指标，包括平均扩散率（MD）、各向异性分数（FA）、扩散幅度（L）和纯各向异性（q），来研究不同损伤间隔的重复性轻度创伤性脑损伤（rmTBI）的长期影响。
将 18 只大鼠随机分为三组：短间隔 rmTBI（n=6）、长间隔 rmTBI（n=6）和假手术对照（n=6）。在 rmTBI 后 50 天和 90 天进行纵向扩散张量成像，分析 MD、FA、L 和 q 值。对神经元、星形胶质细胞、小胶质细胞和髓鞘进行免疫组织化学染色。采用方差分析、皮尔逊相关系数和简单线性回归模型进行分析。
rmTBI 后 50 天，短间隔组皮质下 FA 和 q 值降低（p≤0.038）。相反，长间隔组胼胝体下 FA 和 q 值升高（p≤0.039）。在同侧外囊和内囊，FA 无明显变化，而短间隔组 90 天 L 和 q 值降低（p≤0.028）。外囊和内囊的 q 值与小胶质细胞数量和总星形胶质细胞数量呈负相关（p≤0.035）。
张量标量测量，如 L 和 q 值，对间隔较短的 rmTBI 引起的慢性加重损伤敏感，并反映累积损伤引起的长期星形胶质增生。
张量标量测量，包括 L 和 q 值，是检测 rmTBI 后长期和细微损伤的潜在 DTI 指标；特别是 q 值可用于量化 rmTBI 后远隔白质（WM）的变化。
慢性重复轻度创伤性脑损伤后，L 和 q 值发生改变。在冲击部位和远隔 WM 观察到 q 值的变化。远隔 WM 下较低的 q 值与星形胶质增生有关。
