中文摘要：

目的探讨DTI评价坐骨神经挤压伤的价值。方法建立32只兔坐骨神经挤压伤模型,并随机分为8组,每组4只,分别于损伤后24h、4天、8天、2周、4周、6周、8周、10周行DTI及纤维束示踪,并对4只兔在建模前扫描作为损伤前组;测量并比较损伤前及各时间段损伤远端坐骨神经FA值、λ⊥及λ∥,分析光镜及电镜下损伤远端神经的病理改变。结果 DTI纤维束重建显示挤压伤后远端神经截断,2周后远端纤维束逐渐增多,至10周时接近损伤前。损伤后24hFA值较损伤前下降（P〈0.01）,损伤4天后FA值显著降低（P〈0.001）;6周后FA值显著回升（P〈0.001）,10周FA值仍低于损伤前（P〈0.01）。损伤后4天远端λ⊥显著升高（P〈0.001）,6周后显著回落（P=0.007）,10周后λ⊥恢复至损伤前水平。损伤后远端λ∥无显著变化。损伤远端FA值及λ⊥的变化与病理改变基本一致。结论 DTI能够反映兔坐骨神经挤压伤后神经变性及再生过程。

英文摘要：

Objective： To explore the value of DTI in evaluating sciatic nerve crush injury of rabbit models. Methods： Sciatic nerve crush injury model of 32 New Zealand rabbits were established and randomly divided into 8 groups （each n=4）. DTI scan and tractography were performed 24 h, 4 days, 8 days, 2 weeks, 4 weeks, 6 weeks, 8 weeks and 10 weeks after injury accordingly, and 4 normal rabbits were scanned before building model （pre-injury group）. FA, λ⊥ and λ// of sciatic nerve distal to the injury site were measured and compared. Meanwhile, the pathologic changes of the injured nerve were analyzed under light microscope and electron microscope. Results： DTI tractography showed that the distal part of injured nerve were invisible after injury, emerged 2 weeks after injury and increased in number and length gradually thereafter. The nerve fibers showed close to pre-injury level until 10 weeks after injury. FA of distal injured nerve dropped 24 h after injury （P〈0.01）, dropped significantly 4 days after injury （P〈0.001）, increased significantly 6 weeks after injury （P〈0.001）, but remained lower than pre-injury group 10 weeks after injury （P〈0.01）. λ⊥ of the distal injured nerve increased significantly 4 days after injury （P〈0.001）. Six weeks after injury, λ⊥ dropped back significantly （P=0.007） and returned to pre-injury level 10 weeks after injury. There was no significant difference of λ// of the distal nerve after injury. FA and λ⊥ changes after injury were compatible with the pathologic changes. Conclusion： DTI is useful in reflecting degeneration and regeneration of rabbit sciatic nerve after crush injury.