摘要目的 建立弥漫性轴索损伤(diffuse axonal injury,DAI)动物模型并探讨其早期影像学表现. 方法 选取25只成年新西兰大白兔按随机数字表法分为对照组(5只兔)、轻度DAI组和重度DAI组(6只),轻度DAI组又分3h(6只)、1 d(4只)及1周(4只)组,行弥散张量成像(diffusion tensor imaging,DTI)检查,并测量各项异性分数(fractional anisotropy,FA)、表观弥散系数(apparent diffusion coefficient,ADC)、轴向弥散度度(axial diffusivity,AD)及径向弥散度(radical diffusivity,RD). 结果 与对照组比较,重度DAI组大白兔脑白质FA明显升高(P＜0.01),ADC降低(P＜0.05),RD降低(P＜0.01),AD未见明显改变(P＞0.05).轻度DAI 3 h和1周组各项参数无明显改变,轻度DAI 1 d组FA明显升高(P＜0.01),RD降低(P＜0.05),ADC及AD无明显变化.结论 DTI是探索DAI发生及发展过程的一种敏感性成像方法,可为DAI早期诊断提供影像参考.

abstractsObjective To establish animal models of diffuse axonal injury (DAI) and discuss the early functional MRI findings.Methods Twenty-five adult white rabbits were divided into control group (n =5),mild DAI group and severe DAI group (n =6) according to random number.Mild DAI group was subdivided into mild DAI 3 h (n =6),1 day (n =4) and 1 week (n =4) groups.Routine MRI and diffusion tensor imaging (DTI) were performed.Parameters measured were fractional anisotropy (FA),apparent diffusion coefficient (ADC),axial diffusivity (AD) and radical diffusivity (RD).Results Significantly increased FA (P＜0.01) and decreased ADC (P＜0.05) and RD (P＜0.01) were detected in severe DAI group compared to control group,but there was no significant variation in AD between the two groups (P ＞ 0.05).Each parameter remained almost unchanged in mild DAI 3 h group and mild DAI 1 week group,but FA was increased (P ＜ 0.01) and RD decreased (P ＜ 0.05) in mild DAI 1 day group,with no changes of ADC and AD.Conclusion DTI is a sensitive way to detect the occurrence and development of DAI and can provide referential images for early DAI diagnosis.