中文摘要：

目的观察大鼠弥漫性轴索损伤（DAI）模型伤后不同时间大脑白质磁共振弥散张量成像（DTI）弥散参数和β-APP、NF68免疫组织化学染色的变化。方法建立SD大鼠Marmarou DAI模型,分别于伤后3、12、24、72 h行DTI扫描,获取大鼠胼胝体、内囊和外囊弥散参数;比较相应部位β-APP单位面积阳性轴索数及阳性染色面积百分比,NF68平均光密度的伤后变化。结果实验组胼胝体、内囊和外囊轴向弥散（AD）、各向异性分数（FA）伤后逐步下降;β-APP单位面积阳性轴索数量、阳性染色面积百分比及NF68平均光密度伤后逐步增加。相关分析证实AD、FA值与β-APP、NF68变化呈显著负相关。结论 DTI弥散参数可作为DAI早期诊断的生物标记物。

英文摘要：

Objective To investigate the characteristics of diffusion diffusivities in diffusion tensor imaging（DTI） and immunohistochemical evidence demonstrated by β-APP and NF68 in different time after trauma in the white matter of cerebrum in rats with diffuse axonal injury（DAI）.Methods The model of DAI was established in the rats,then the animals were imaged with DTI at multiple time points-3,12,24 and 72 h respectively.The corpus callosum,bilateral external capsule and internal capsule were studied to obtain the diffusion parameters,the corresponding counts and the percentage of positive area of axons demonstrated by β-APP immunohistochemical staining,as well as the mean density of NF68 immunohistochemical staining.Results Fraction anisotropy（FA） and axial diffusivity（AD） were dramatically and consistently decreased after trauma in the ROIs in the experimental group,but the corresponding counts and the percentage of positive area of axons verified by β-APP immunohistochemical staining and the mean density of NF68 immunohistochemical staining increased.The data shown that the values of FA and AD were obviously negatively correlated with the changes of β-APP and NF68.Conclusion Diffusion diffusivities of DTI could be used as biomarkers in the early diagnosis of DAI.