Interobserver agreement for contrast-enhanced ultrasound of liver imaging reporting and data system: A systematic review and meta-analysis

BACKGROUND: Hepatocellular carcinoma is the most common primary liver malignancy. From the results of previous studies, Liver Imaging Reporting and Data System (LI-RADS) on contrast-enhanced ultrasound (CEUS) has shown satisfactory diagnostic value. However, a unified conclusion on the interobserver stability of this innovative ultrasound imaging has not been determined. The present meta-analysis examined the interobserver agreement of CEUS LI-RADS to provide some reference for subsequent related research. AIM: To evaluate the interobserver agreement of LI-RADS on CEUS and analyze the sources of heterogeneity between studies. METHODS: Relevant papers on the subject of interobserver agreement on CEUS LI-RADS published before March 1, 2020 in China and other countries were analyzed. The studies were filtered, and the diagnostic criteria were evaluated. The selected references were analyzed using the “meta” and “metafor” packages of R software version 3.6.2. RESULTS: Eight studies were ultimately included in the present analysis. Meta-analysis results revealed that the summary Kappa value of included studies was 0.76 [95% confidence interval, 0.67-0.83], which shows substantial agreement. Higgins I(2) statistics also confirmed the substantial heterogeneity (I(2) = 91.30%, 95% confidence interval, 85.3%-94.9%, P < 0.01). Meta-regression identified the variables, including the method of patient enrollment, method of consistency testing, and patient race, which explained the substantial study heterogeneity. CONCLUSION: CEUS LI-RADS demonstrated overall substantial interobserver agreement, but heterogeneous results between studies were also obvious. Further clinical investigations should consider a modified recommendation about the experimental design.