Grading fatty liver and detecting liver pathological features - Is there consensus between sonographers and radiologists?

Introduction Hepatic steatosis is the leading cause of chronic liver disease. Reliable detection and staging of liver disease is important to facilitate diagnosis and treatment. The aim of this study was to evaluate the interobserver agreement between trainee sonographers, qualified sonographers and radiologists in grading non-alcoholic fatty liver disease (NAFLD) and detecting common liver pathological features in B-mode images. Methods 150 B-mode liver ultrasound images from 50 adult patients referred for an abdominal ultrasound were obtained retrospectively from a PACS system. The images were independently graded for the severity of hepatic steatosis (normal, mild, moderate or severe) and the detection of incidental 0findings, focal fatty sparing, liver surface irregularity and rounded liver edge (present or absent) by 17 qualified, six trainee sonographers and six radiologists. Fleiss’ kappa statistics were used to calculate interobserver agreement among participants in grading common liver pathological features. Intraclass correlation coefficient (ICC) were used to calculate the level of absolute agreement among participants in grading NAFLD. Results The interobserver agreement rates among trainee sonographers for the detection of incidental findings, focal fatty sparing, liver surface irregularity and rounded liver edge were: κ = 0.243, 0.486, 0.155 and 0.079 respectively. Among qualified sonographers, the agreement rates were: κ = 0.323, 0.428, 0.167 and 0.152 respectively. Among radiologists, the agreement rates were: κ = 0.156, 0.266, 0.015 and 0.154 respectively. The intraclass correlation coefficient average scores among trainee sonographers, qualified sonographers, all the sonographers combined and radiologists were: 0.927, 0.978, 0.985 and 0.954 respectively. Conclusion Visual assessment of common liver pathology in B-mode imaging has low interobserver agreement among sonographers and radiologists, but excellent inter-rater reliability in grading NAFLD. The low agreement levels are likely caused by a lack of standardised assessment criteria. The development of a standardised criteria for staging NAFLD and common liver pathological features are recommended.