超声实时剪切波弹性成像评价脂肪肝的价值

Evaluation of shear wave elastography in diagnosing fatty liver

目的:应用超声实时剪切波弹性成像(SWE)技术测量人体脂肪肝硬度的变化,分析脂肪肝硬度(kPa_(Mean))与MR mDixon测得的脂肪含量的相关性,探讨脂肪肝硬度的诊断阈值及SWE技术对脂肪肝的诊断价值。方法:对26例志愿者行传统二维超声、SWE及MR mDixon序列检查。超声检查由两位医师分别进行操作和数据测量,并分析两位医师间的一致性;通过计算Pearson相关系数r1、r2分析两位医师内的可重复性。对SWE测得的硬度值、速度值及MR mDixon测得的脂肪含量分别与传统超声在脂肪肝检出及分度上进行一致性分析,绘制散点图,并得到kPa_(Mean)诊断阈值;对SWE和MR mDixon的测量结果进行相关性分析,计算Pearson相关系数。结果:检验两位医师间的一致性的BlandAltman散点图显示26例中有24个数据位于95﹪一致性界限内;检验两位医师内的可重复性的Pearson相关系数r1=0.917、r2=0.921(P值均<0.05);分别计算kPa_(Mean)界值=4、5、6时的Kappa值,当杨氏模量诊断阈值kPa_(Mean)为5kPa时,Kappa值为0.819>0.75(P<0.05);SWE测得的硬度值(kPa_(Mean))、速度值与MR脂肪含量的Pearson相关系数分别为0.877、0.867,差异均有统计学意义(P值均<0.05)。结论:SWE成像技术诊断脂肪肝具有较好的稳定性,可为临床提供脂肪肝患者肝脏硬度方面的信息,与MR mDixon序列检测的肝脏脂肪含量有很高的相关性。

Objective：To investigate the change of fatty liver stiffness by real-time shear wave elastography （SWE）, and to obtain the diagnostic threshold of fatty liver by comparing with conventional two-dimensional ultrasound and MR mDixon sequence which were used to detect the liver fat content. To analyze the correlation between fatty liver stiffness and fat content. And to assess the value of ultrasound SWE technique in diagnosis of fatty liver. Methods： 28 healthy volunteers were examined by conventional two-dimensional ultrasound,SWE and MR mDixon sequence. The consistency between the observers of SWE technique was examined by the Bland Altman plot. The repeatability within the observers of the SWE technique was examined by calculating Pearson correlation coefficient r1. r2. The consistency of the ultrasound SWE tech- niques,MR mDixon sequence and traditional ultrasound in the detection and grade of fatty liver were analyzed to obtain the diagnostic threshold （kPaMcan） combined with the scatter plot. To analyze the correlation of two imaging methods by calcu- lating the Pearson correlation coefficient. The correlation of two imaging methods were analyzed by calculating the Pearson correlation coefficient. Results：Bland-Altman plot showed that 24 cases were within the 95% agreement limit in 26 healthy volunteers. Intra-group correlation coefficients were r1= 0.917, r2 = 0.921 （P〈 0. 05）. Kappa values of kPaMo,n = 4,5,6 were calculated respectively. When Young＇s modulus diagnostic threshold （kPaMoan） was seted at 5kPa, Kappa value= 0. 819 〉0.75 （P〈0.05）. Pearson correlation coefficient was r hardness=0. 877〉0.85, r velocity=0. 867〉0.85, with a signifi- cantly statistical difference （all P〈0.05）. Conclusion： SWE imaging technique can be applied to the measurement of fatty liver with good stability,it can be used not only in clinical detection of fatty liver,but also can provide information about liv- er stiffness in patients with fatty liver, and it has a high correlation with liver fat content detected by MR mDixon sequence.