MR弹性成像与T1ρ成像诊断肝脏纤维化分期的对比实验研究

Noninvasive assessment of hepatic fibrosis staging with MR elastography versus T1ρ imaging

目的对比MR弹性成像（MRE）和T1ρ成像诊断肝纤维化（HF）分期的价值。方法纯种健康新西兰大白兔60只，采用动物随机区组分组法分成造模组HF（44只）和对照组（16只）。HF组兔通过皮下注射CCl4溶液的方法建立HF模型。HF组分别于注射CCl4后第4、5、6周时各任意选取8只，对照组每次选取4只，第10周为两组剩余兔行肝脏常规扫描、MRE及T1ρ成像。完成MRI扫描后行肝脏病理检查，进行纤维化Scheuer分期（F0~F4期）。在MRE和T1ρ图像上分别测量肝脏硬度值和T1ρ值。采用单因素方差分析比较不同肝纤维化分期组间肝脏硬度值和T1ρ值的差异，采用Spearman分析评价肝脏硬度值和T1ρ值与病理分期的相关性，采用ROC评价MRE与T1ρ成像诊断HF分期的效能。结果剔除图像质量差和死亡兔，2组共43只兔纳入研究，F0期10只、F1期8只、F2期8只、F3期8只、F4期9只。F0、F1、F2、F3和F4期兔的肝脏硬度值分别为（1.051±0.155）、（1.335±0.235）、（1.401±0.163）、（2.001±0.499）、（2.981±0.714）kPa，T1ρ值分别为（23.20±4.02）、（24.28±2.93）、（25.40±1.82）、（24.69±1.85）、（31.54±3.39）ms，差异均有统计学意义（P均〈0.05）。肝脏硬度值、T1ρ值和HF分期均具有正相关性（r值分别为0.916、0.608，P均〈0.01）。硬度值诊断不同分期肝纤维化的ROC下面积为0.938~0.989，T1ρ值的ROC下面积为0.771~0.954，MRE优于T1ρ成像。结论MRE诊断肝纤维化分期优于T1ρ成像。

ObjectiveTo compare the diagnostic values of magnetic resonance elastography （MRE） and T1ρ imaging in staging hepatic fibrosis （HF） in a rabbit model. MethodsThe institutional animal care and use committee approved all experiments. Sixty healthy rabbits were divided into HF group （n=44） and control group （n=16）. Each eight rabbits in the HF group and 4 rabbits in the control group were randomly selected at the 4th, 5th, 6th week and the remaining rabbits at the 10th week after subcutaneous injection with 0.1 ml 50% CCl4 oily solution per kilogram of body respectively, to undergo liver MR scan including axial liver MRE and T1ρ imaging. The values of liver stiffness （LS） and T1ρ were measured. Masson trichrome staining of liver tissue was used. According to the Scheuer scoring system, rabbits were classified into F0 to F4 group based on the percentage of hepatic fibrosis. The difference of LS values and T1ρ values among stage F0 to F4 were compared by the one-way ANOVA analysis. The correlations between pathological staging and LS, T1ρ values were performed by the Spearman correlation analysis. ROC curve analysis was performed to compare the value of MRE with T1ρ imaging.ResultsForty three rabbits were included, there were 10, 8, 8, 8, 9 rabbits in F0, F1, F2, F3 and F4 stage, respectively. LS values were （1.051±0.155）, （1.335±0.235）, （1.401±0.163）, （2.001±0.499） and （2.981±0.714） kPa in F0, F1, F2, F3 and F4, respectively, while T1ρ values were （23.20±4.02）, （24.28±2.93）, （25.40±1.82）, （24.69±1.85） and （31.54±3.39） ms （all P〈0.05）. The correlation of LS values with hepatic fibrosis staging measured on MRE was stronger than T1ρ values （r values were 0.916 and 0.608, all P〈0.01）. Area under ROC curve of LS value for differentiating hepatic fibrosis stage were 0.938 to 0.989, while the areas of T1ρ were 0.771 to 0.954.ConclusionMR elastography is an accurate technique for quantitatively staging hepatic fibrosis and superior to T1ρ imaging.