大鼠肝大部分切除术后T1和T2值变化及其与肝再生过程关系的研究

Experimental study on the changes of T1 and T2 values in residual liver of rats after major liver resection and their relationship with liver regeneration process

目的探讨大鼠肝大部分切除术后残肝T1和T2值变化过程及其与肝再生相关病理指标的关系。方法健康雄性Sprague-Dawley大鼠70只,SPF级,鼠龄7~8周,重量250~280 g,分成MR扫描组(n=14)和病理分析组(n=56)。MR扫描组又分为肝部分切除术组(2/3肝切除,n=7)和假手术组(n=7)。均于术前和术后第1、2、3、5、7、14、21天行磁共振T1 mapping和T2 mapping扫描,测量肝实质T1和T2值。病理分析组在术前及术后上述每个时间点随机选取7只实验鼠取肝脏组织进行病理学检查,测量肝细胞直径和肝细胞增殖活性(Ki-67指数)。观察影像学指标和病理指标的变化规律,分析MR参数与肝脏体积及病理指标间的相关性。结果肝实质T1和T2值均于术后第1天升高,且均于术后第2天达到最大值(P<0.05);随后逐渐下降,分别于术后第14天和第21天恢复至术前水平(P均>0.05)。T2值与肝体积、肝细胞直径及Ki-67指数均存在较好相关性(r值分别为-0.764,0.640,0.765,P均<0.001)。T1值和肝体积、肝细胞直径及Ki-67增殖指数均存在相关性(r值分别为-0.481,0.472,0.444,P均<0.001)。结论大鼠肝大部分切除后残肝实质T1和T2值出现规律变化,且与肝脏再生指标存在相关性,可反映大鼠肝脏大部分切除后肝实质的微观变化,有望被用于定量监测残肝再生过程。

Objective To investigate the changes of T1 and T2 values in residual liver after major liver resection in rats and the relationship with pathologic indices related to liver regeneration.Methods Seventy healthy male Sprague Dawley rats,SPF grade,aged 7-8 weeks,weighting 250-280 g,were divided into MR scan group(n=14)and pathologic analysis group(n=56).The MR scan group was further divided into partial hepatectomy group(n=7)and the sham operation group(n=7).MRI T1 mapping and T2 mapping were performed before surgery and on day 1,2,3,5,7,14,21 after surgery.T1 and T2 values of liver parenchyma were measured.In the pathologic analysis group,7 rats were randomly included at each time point before and after surgery for pathologic examination,the diameter and proliferative activity(Ki-67 indices)of hepatocytes were assessed.The changes of imaging and pathologic indices were observed,and the correlations between MR parameters and liver volume and pathologic indices were analyzed.Results Both T1 and T2 values in liver parenchyma were increased on day 1 after surgery and reached their maximum values on day 2(P=0.005 and P<0.001,compared with baseline),then were gradually decreased,and recovered to the preoperative level on day 14 and 21(P>0.05),respectively.T2 value was correlated with hepatocyte diameter,liver volume and Ki-67 indices better(r=0.640,-0.764,0.765,respectively,all P<0.001).T1 value was correlated with hepatocyte diameter,liver volume and Ki-67 indices(r=0.472,-0.481 and 0.444,all P<0.001).Conclusion The T1 and T2 values of rats liver remnant parenchyma showed regular changes,and were correlated with liver regeneration indices,which reflect the microscopic changes of rat liver remnant parenchyma,and are expected to be used for quantitative monitoring of liver remnant regeneration.