中文摘要：

目的探讨DTI评估兔坐骨神经放射性损伤的可行性和准确性,分析各弥散参数（FA、ADC、λ⊥、λ∥）与病理及肢体功能的关系。方法选取21只新西兰大白兔,随机选取一侧后肢行单次立体定向辐照制作坐骨神经放射性损伤模型。对实验兔于辐照前、辐照后1天、1、2、3、4个月行DTI及T2WI、SPIR扫描,同时评价肢体功能变化,检查完毕后于各时间点随机处死2只兔行电镜检查。结果辐照前,辐照侧与对照侧各DTI参数差异均无统计学意义（P均〉0.05）。辐照后1天,辐照侧FA值与对照侧差异无统计学意义（P=0.075）;辐照后1、2、3、4个月辐照侧FA值均低于对照侧（P均〈0.05）。辐照后1天、1、2、3、4个月,辐照侧λ⊥及ADC值均高于对照侧（P均〈0.05）。FA值与肢体功能呈正相关（r=0.833,P=0.039）,λ⊥值与肢体功能呈负相关（r=-0.833,P=0.039）,ADC、λ∥值与肢体功能无相关性（r=-0.586、-0.463,P均〉0.05）。结论 FA及λ⊥随时间变化的趋势与肢体功能及病理改变相一致,可作为评价兔周围神经放射性损伤的可靠方法。

英文摘要：

Objective To evaluate the feasibility and accuracy of DTI parameters （FA, ADC, λ⊥ andλ∥） in assessing ra- diation-induced injury of sciatic nerve in rabbit models and the relationship of histologic, functional recovery and DTI pa- rameters. Methods A total of 21 New Zealand white rabbits were used. One side of sciatic nerve in each rabbit was ran- domly selected to produce radiation-induced injury model. The limb function of rabbit were assessed before and after irradi- ation at different time point（1 day, 1, 2, 3 and 4 months）. MR scans including DTI, T2WI, SPIR were also performed on each time point. Two rabbits were randomly sacrificed for histologic evaluation at each time point. Results There was no statistical difference of DTI parameters between irradiated and control nerves before irradiation （all P〉0. 05）. No statisti- cal difference of FA value was found 1 day after irradiation between irradiated and control nerves （P=0. 075）. FA value of irradiated nerve was respectively lower than that of control nerve 1, 2, 3 and 4 months after irradiation （all P〈0.05）. The ）λ⊥ and ADC values of irradiated nerve were statistically higher than those of control nerve （all P〈0. 05）. Changes of FA correlated well with functional changes in irradiated limb （r=0. 833, P=0. 039）, while ）λ⊥ negatively correlated with func- tional changes （r=-0. 833, P=0, 039）. ADC and ）λ∥/values were not related to limbs function （r= -0. 586, -0. 463, both P〉0.05）. Conclusion FA and λ⊥ values can be used as a reliable method for evaluating radiation-induced damage of peripheral nerve in rabbit models.