核磁共振动态增强成像评价肝纤维化的临床应用

Application of dynamic contrast-enhanced magnetic resonance imaging in evaluating liver fibrosis

目的探讨核磁共振(MR)动态增强时间信号曲线(TIC)定量参数评价肝纤维化程度的价值。方法患者及健康志愿者共36人行肝脏MR常规及动态增强扫描,依据肝纤维化程度分为正常组(n=9)、轻度纤维化(n=5)、中重度纤维化(n=7)及肝硬化(n=15)共4组。获取门静脉、肝、脾的TIC,评价峰高、TTP、信号上升最大斜率(MSI)和信号下降最大斜率(MSD)等TIC量化参数与肝纤维化程度的相关性,运用ROC曲线评价TIC斜率指标诊断肝纤维化程度的效力。结果各ROI的TIC曲线的峰高、MSI、肝脾的MSD均与纤维化程度呈负相关关系(P<0.05,r为-0.446～-0.800),TTP与之呈较为密切的正相关关系(P<0.05,r>0.5)。ROC曲线分析显示:诊断轻度肝纤维时,各斜率指标曲线下面积(AUC)依次为0.747～0.783,其中脾MSD曲线下面积最大;诊断中度以上纤维化(S≥3)时,AUC为0.728～0.877,由小到大对应的指标依次为动脉期肝MSI、门静脉MSI、门静脉期肝MSI、肝MSD、动脉期脾MSI、脾MSD;诊断肝硬化时,AUC为0.742～0.821,由小到大对应的指标依次为门静脉期肝MSI、肝MSD、动脉期肝MSI、门静脉MSI、动脉期脾MSI、脾MSD。结论 MR动态增强TIC能反映肝纤维化进程的血流动力学变化,是一种无创评价肝纤维化程度的功能影像学方法。

Objective To analyze the value of time-signal intensity curve（TIC） in dynamic contrast-enhanced magnetic resonance imaging（DEC-MRI） in the evaluation of liver fibrosis.Methods Thirty-six consecutive patients and healthy volunteers were divided into 4 groups according to the stages of fibrosis,namely the normal group（n=9）,mild fibrosis group（n=5）,moderate to severe fibrosis group（n=7）,and liver cirrhosis group（n=15）.All the subjects underwent conventional and DEC-MRI,and the TIC was generated automatically to evaluate the peak height,TTP,MSI and MSD.The correlations between the TIC parameters and the stage of fibrosis were assessed.Receiver operating characteristic（ROC） curve analyses were conducted to evaluate the value of the TIC parameters in the evaluation of fibrosis stage.Results Moderate but significant inverse correlations of the peak height,MSI,and to fibrosis stage were noted in these patients（P〈0.05）;the peak time was positively correlated to the fibrosis stage（P〈0.05）.In patients with a fibrosis stage ≥1,the AUC of the measured TIC parameters ranged from 0.747 to 0.783,with the MSD of the spleen had the highest AUC（0.783）.For a fibrosis stage ≥3,the AUC of the indices ranged between 0.728 and 0.877,highest for liver MSI of the arterial phase,followed by the portal vein MSI,liver MSI of portal venous phase,liver MSD,splenic MSI of arterial phase and splenic MSD.In the diagnosis of liver cirrhosis,the AUC（range 0.742-0.821） decreased in the order of liver MSI of the portal venous phase,liver MSD,liver MSI of the arterial phase,the portal vein MSI,splenic MSI of the arterial phase and splenic MSD.Conclusion TIC of DEC-MRI can be used to evaluate hemodynamic changes in the liver,and may serve as a practical non-invasive functional imaging modality for assessing the severity of liver fibrosis.