磁敏感加权成像诊断早期肾缺血再灌注损伤的初步实验观察

Evaluate the early changes of renal ischemia-reperfusion by susceptibility weighted imaging：primary experiment study

目的 利用兔肾脏缺血再灌注（IRI）模型探讨磁敏感加权成像（SWI）能否反映肾脏IRI早期改变.方法 新西兰大白兔34只,每只兔左肾结扎60 min制作兔肾IRI模型,于结扎前、结扎后0.5、24和48 h分别行MR扫描,包括SWI和T2 WI序列等,分析兔肾IRI后皮髓质信号的变化并与病理相对照.结果 结扎前正常兔肾T2 WI呈内髓高信号、外髓明显低信号及皮质稍高信号三带分布,SWI上外髓呈明显低信号,内髓及皮质呈高信号;结扎后0.5h肾肿胀明显,T2 WI上皮质带变薄,内髓、外髓带增宽,外髓低信号带模糊变淡,内髓及皮质带信号略升高,SWI上外髓带信号明显升高;24、48 h皮髓质分界逐渐清楚,SWI显示外髓带信号仍高于结扎前,并出现点状、条状低信号出血点.SWI和T2WI在IRI后0.5、24、48 h外髓外带发现点状出血灶的平均数目分别为0、2.50、6.75（F=52.17,P＜0.01）;0、1.13、2.88（F=15.65,P＜0.01）,配对t检验显示SWI和T2WI对出血灶检出差异有统计学意义（t =4.83,P＜0.01）.结论 SWI能显示肾脏尤其是外髓带IRI后的改变,对评估早期肾IRI有一定价值.

Objective To explore whether susceptibility weighted imaging （SWI） could diagnose the early changes of renal IRI in vivo by modeling the renal ischemia-reperfusion （IRI） of rabbit.Methods Thrity four New Zealand white rabbits were chosen, the vesseles of the left kidney of rabbits were ligated for 60 minutes, then the renal ischemia-reperfusion model was established.Respectively, the rabbits before ligation, 0.5,24 and 48 h after the ligation, were examined with MR , then the signal of the cortex and medulla was analyzed in SWI and T2WI, the imaging features were compared with histopathology.Results The inner medullary of renal showed high signal, low signal in the outer medulla and mildly high in the cortex before ligation in T2 WI sequence, which showed the typical three-band signal distribution, while the outer medulla showed wildly hypo-signal in SWI, the remnants showed high signal;kidney swelled significantly 0.5 hour after ligation, the stripe of cortex became thin, however, the inner medulla and outer medulla widened.The hypo-signal of the outer medulla faded, while the signal of inner medullary and cortical slightly elevated.The signal intensity of outer medulla lowered more obviously in SWI, the margin of the cortex and medulla became more clearly 24 and 48 h after ligation, However the signal of the outer medulla was higher than normal kidney in the SWI, and punctuate or stripe haemorrhage occurred in the outer medulla.Respectively, the number of punctuate, stripe haemorrhage detected by SWI in the out medulla of kidney 0.5,24 and 48 h after ligation were 0, 2.50,6.75 （F =52.17, P 〈 0.01）, Meanwhile, the number detected by T2 WI was 0, 1.13,2.88 （F =15.65, P 〈 0.01）;the number of hemorrhage which was detected by SWI and T2WI in the outer medulla among different timepoint have the statistical significance（t =4.83, P 〈 0.01）.Conclusion SWI can clearly show early changes in IRI-renal, especially in the outer medulla of the renal, the technique was helpful to assess the early changes of renal IRI.