磁共振DTI诊断兔急性肝缺血再灌注损伤的价值

Diffusion tensor imaging assessment of acute hepatic ischemia reperfusion injury in a rabbit model

目的探讨磁共振扩散张量成像(DTI)参数平均扩散系数(Dcavg)和各项同向系数(FA)对兔急性肝缺血再灌注损伤(IRI)的诊断价值。方法新西兰大白兔21只,将其中18只兔制成IRI模型,结扎肝左叶血供60 min后恢复血供,随机分为1、2和6 h组,每组6只;另外3只作为对照组,仅解剖肝十二指肠韧带,未阻断血供。b值分别选取100、300和600 s/mm^2,检查结束后行病理学检查。结果Dcavg变化规律:在1 h组显著下降,且b=100 s/mm^2(P<0.001)、300 s/mm^2(P=0.008)时,与sham组间差异存在统计学意义;在I/R后2 h显著升高,并在b=100 s/mm^2时(P=0.021),与sham组间存在统计学意义;b=100(P<0.001)、300 s/mm^2(P=0.002),6 h组与sham差异存在统计学意义。FA变化规律:1 h组FA显著升高(b=100 s/mm^2,P=0.032;300 s/mm^2,P<0.001);2 h组显著减低,均与sham组间差异均存在统计学意义(b=100 s/mm^2,P<0.001;300 s/mm^2,P=0.004)。FA在6 h组减低,与sham间无显著性差异(P>0.05)。结论采用较小的b值(≤300 s/mm^2),平均扩散系数(Dcavg)能够准确反映急性肝IRI早期肝窦淤血、微循环障碍等病理过程,而FA则反映肝IRI后组织微细空间结构改变等病理过程。

Objective To explore the use of Dcavg and FA values for assessing acute hepatic ischemia reperfusion injury（IRI）in rabbit models.Methods IRI models were established in 21 New Zealand white rabbits.18 rabbits were divided into three groups of 6 rabbits undergoing 60 minutes of left hepatic lobe ischemia followed by 1 h,2 h and 6 h of reperfusion.The remaining 3rabbits were used as control without hepatic ischemia.DTI was performed using b values of 100 s/mm^2,300 s/mm^2 and 600 s/mm^2.The Dcavg and FA values were correlated with histology.Results The Dcavg values decreased in the 1 h reperfusion rabbits and were significantly lower than those in the control group at b values of 100 s/mm^2（P〈0.001）and 300 s/mm^2（P=0.008）.The Dcavg values increased in the 2 h reperfusion group and were significantly higher than those in the control group at b value of 100 s/mm^2（P=0.021）.The Dcavg values of the 6 h reperfusion group were significantly higher than that of the control group at b values of100 s/mm^2（P=0.021）and 300 s/mm^2（P=0.002）.FA increased in the 1 h reperfusion group（b=100 s/mm^2,P=0.032;b=300 s/mm^2,P〈0.001）,and then declined slightly in the 2 h reperfusion group（b = 100 s/mm^2,P〈0.001;b=300 s/mm^2,P=0.004）.After that,FA decreased slightly in the 6 h reperfusion group without significant difference compared to the control group（P〈0.05）.Conclusion The Dcavg and FA values reflect the microvascular and structural changes of hepatic IRI in rabbits particularly at early stages with small b values≤300 s/mm^2.