中文摘要：

目的探索磁共振弥散张量成像（diffusion tensor imaging,DTI）在大鼠锥体束损伤中的应用价值。方法建立大鼠Marmarou模型,伤后3、12、24及72 h行磁共振DTI扫描,探索大鼠双侧锥体束弥散参数、β-淀粉样前体蛋白（β-amyloid precursor protein,β-APP）单位面积阳性轴索数和阳性染色轴索面积百分比、神经丝（neurofilament,NF）68平均光密度和积分光密度改变规律。结果实验组锥体束轴向弥散（axialdiffusivity,AD）、各向异性分数（fraction anisotropy,FA）和相对各向异性（relative anisotropy,RA）呈持续性下降,伤后72h达到最低值（P〈0.05）,此与β-APP及NF68免疫组织化学染色观察指标变化趋势相对应。相关分析证实AD、FA和RA与β-APP染色指标均呈显著负相关。结论 DTI对锥体束损伤的早期诊断具有重要的应用价值。

英文摘要：

Objective To explore the applicability of magnetic resonance diffusion tensor imaging （DTI） for diagnosis of pyramidal tract damage in rats. Methods Marmarou＇s model was set up, followed by DTI scanning at 3, 12, 24 and 72 h post trauma to acquire the dispersion parameter of bilateral pyramidal tracts. Moreover, axonal varicosities per square millimeter and the percentage of positive area of axons demonstrated by/3-amyloid precursor protein （β-APP） immunostaining were obtained, as well as the mean density and sum density of neurofilament（NF） 68 immunostaining. Results Axial diffusivity（AD）, fraction anisotropy（FA） and relative anisotropy（RA） in the pyramidal tract were significantly and continuously re- duced and reached to the bottom at 72h post trauma（P〈0.05） in accord with the gradient of axonal damage verified by β-APP and NF68 immunostaining. Furthermore, the changes of AD, FA and RA showed a sig- nificant negative correlation with the β-APP immunohistochemieal results. Conclusion DTI has important value for early diagnosis in pyramidal tract damage.