횡탄성 초음파 영상을 이용한 간탄력도 측정의 변동계수가 미만성 간질환 환자에서의 진단능을 높이는가?

Abstract

Purpose The aim of this study was to compare the applicability of the coefficient of variation (CV) and interquartile range divided by the median liver stiffness value (IQR/M) in the liver stiffness (LS) measurement by shear wave elastography (SWE) to raise the diagnostic accuracy in the patients with diffuse liver disease using the histologic reference method.

Materials and Methods We consecutively analyzed 96 patients with various diffuse liver diseases who underwent both of SWE and liver biopsy. Liver fibrosis was staged from F0 to F4 according to the METAVIR scoring system. The mean, median and CV of the LS values, IQR/M from each measurement were compared and correlated. The accuracy for the prediction of hepatic fibrosis was analyzed using receiver operating characteristic (ROC) curves.

Results Among 96 patients, 12 patients were belonged to F0, 14 in F1, 23 in F2, 15 in F3 and 32 in F4 stage. The correlation between LS value and hepatic fibrosis stage was significant (mean LS value, r = 0.743, p < 0.001; median LS value, r = 0.734, p < 0.001). Diagnostic accuracy of mean LS for the prediction of advanced fibrosis (≥ F3) was 0.906 (95%CI, 0.829-0.956, P < 0.001), and no significant differences between using mean LS value and median LS value on pairwise comparison. When we applied CV < 20%, diagnostic performance of mean LS showed significantly better than when using CV ≥ 20% (z statistic = 2.23, p = 0.02545), whereas matched cut-off of IQR/M did not. However, these parameters were not good discriminators of any fibrosis (≥ F1) from no fibrosis (F0); of significant fibrosis (≥ F2) from mild/no fibrosis (< F2); of cirrhosis (F4) from no cirrhosis (< F4).

Conclusion The LS measurements by SWE should be considered with its CV and if the LS value showing CV < 20%, it could be considered ‘‘more reliable’’ than those with IQR/M < 0.21 for the assessment of advanced fibrosis. Furthermore, the effort of the operator to measure homogeneous LS considering CV is needed rather than to get the consistent LS values for the normal ranged IQR/M.