扩散峰度与扩散张量成像对比评估兔周围神经急性挤压伤

Comparing diffusion kurtosis imaging and diffusion tensor imaging in the evaluation of peripheral nerve acute crush injury in rabbits

目的:对比扩散峰度成像(DKI)与扩散张量成像(DTI)评估兔周围神经挤压伤的价值。方法:选取新西兰大白兔27只,于右后肢建立坐骨神经损伤与修复模型,左后肢为假手术侧。分别于术前、1、3天、1、2、4、6、8周行DTI及DKI扫描,测量各时间点定量参数,并于各时间点随机取2只兔子行电镜检查。结果:DKI参数中平均峰度(MK)值在损伤后第1天明显下降并在较低水平波动,自第2~8周逐渐上升,损伤侧与假手术侧MK值于2~8周差异均有统计学意义(P<0.05);损伤后1天各向异性分数(FADKI)值明显下降至最低点;3天~8周持续上升,各时间点差异均有统计学意义(P<0.005);径向峰度(RK)值仅在6周时双侧差异有统计学意义(P=0.018);而轴向峰度(AK)值于各时间点均无显著差异(P>0.05)。DTI参数中FADTI与FADKI变化趋势一致且各时间点差异均有统计学意义(P<0.001);ADC值仅在第8周差异有统计学意义(P=0.038)。结论:DKI可用于周围神经急性挤压伤的评估,但与DTI相比,DKI在评估急性周围神经损伤时可能并不能提供额外价值。

Objective:To investigate the value of diffusion kurtosis imaging(DKI)and diffusion tensor imaging(DTI)in the evaluation of peripheral nerve crush injury in rabbits.Methods:A total of 27 healthy New Zealand white rabbits were selected and the right hind limb was selected as the injured side to establish a sciatic nerve injury model,in which sciatic nerve injury was performed after surgical exposure.The left side was the sham surgical side,as the nerve only exposed by operation.The changes of limb function were evaluated by DTI and DKI scanning at the time points of before injury and 1 day,3 days,1 week,2 weeks,4 weeks,6 weeks and 8 weeks after injury,respectively.At each time point,2 rabbits were randomly selected from the injured sciatic nerves for pathological examination.Results:The mean kurtosis(MK)value of DKI parameters decreased significantly on the 1st day after injury and fluctuated at a low level,but gradually increased from the 2nd to the 8th week.The differences of MK value between the injured side and the sham side were statistically significant in all time points(P<0.05).The score of anisotropy(FADKI)decreased to the lowest point one day after injury,while a sustained increase was maintained over three to eight weeks,and FA values at each time point were statistically significant(all P<0.005).Radial kurtosis(RK)was only significantly different at 6 weeks(P=0.018).There was no significant difference in axial kurtosis(AK)at all time points(P>0.05).In DTI parameters,the variation trend of FADTI was consistent with the FADKI in DKI,and the differences at each time point were statistically significant(all P<0.001),while the difference in ADC value was statistically significant only at week 8(P=0.038).Conclusion:DKI can be used to evaluate peripheral nerve crush injury,but it may not provide additional value in the assessment of acute peripheral nerve injury compared with DTI.