MR T2WI显示实验兔坐骨神经损伤

MR T2WI demonstration of sciatic nerve injury in rabbits

目的探讨实验兔坐骨神经损伤后MRI信号、病理改变及与神经功能变化的关系。方法将20只新西兰大白兔随机均分为5组,制作右侧坐骨神经夹伤模型;分别于夹伤后3天、7天、2周、3周和4周行T2脂肪抑制快速恢复自旋回波(T2fs FRFSE)序列扫描,TE分别为30 ms、60ms、90 ms,测量夹伤近端、远端和对照侧神经肌肉信号强度比(SIR)及相对信号强度(ΔS),分析SIR和ΔS与病理改变和实验兔下肢神经功能的关系。结果损伤侧神经夹伤远端SIR和ΔS在损伤后3~7天升高,病理见神经出现空泡变性,张趾功能基本丧失;2周时SIR和ΔS升高达到峰值,髓鞘崩解,张趾功能完全丧失;3~4周时SIR和ΔS逐渐恢复,神经纤维出现再生,张趾功能恢复。夹伤侧TE=90、60ms的T2fs FRFSE图像显示率及神经夹伤远端和近端的SIR均高于TE=30ms图像(P均<0.05)。结论 T2fs FRFSE序列SIR和ΔS可用于评估实验兔神经损伤情况。

Objective To investigate the relationship between MRI signal, pathological changes and neurological function after sciatic nerve injury in rabbits. Methods Twenty New Zealand white rabbits were randomly and evenly divided into 5 groups, and the right sciatic nerve crush models were established. T2 fat suppression fast recovery spin echo （T2 fs FRFSE） sequence scanning was performed 3 days, 7 days, 2 weeks, 3 weeks and 4 weeks after injury, and TE was set as 30, 60 and 90 ms, respectively. Signal intensity ratio （SIR） and relative signal intensity （ΔS） of proximal and distal part of injured nerve and control side nerve were measured. The relationship between SIR, ΔS, pathology and rabbit lower limb nerve function were analyzed. Results In the distal part of injured nerve, SIR and ΔS increased 3-7 days after injury, pathological results showed vacuolar degeneration, and basic toe function lost was found. SIR and ΔS reached the peak 2 weeks after injury, with most serious disintegration of myelin and toe function disable. SIR, ΔS and toe function disable gradually recovered, and the nerve regenerated at 3-4 weeks after injury. The injure display rate of T2 fs FRFSE images with TE=90 and 60 ms, SIR of both distal and proximal part of injured nerve were higher than those on images with TE=30 ms （all P〈0.05）. Conclusion SIR and ΔS changes on T2 fs FRFSE imaging can be used to predict rabbit nerve injury.