Inter‐Reader Agreement for CT and MRI LI ‐ RADS Version 2018: An Individual Participant Data Meta‐Analysis

BACKGROUND: The Liver Imaging Reporting and Data System (LI-RADS) is a classification system to diagnose hepatocellular carcinoma (HCC) noninvasively. The reported LI-RADS inter-reader variability in single-center studies highlights the need to better understand the variability on a broader scale. PURPOSE: Evaluate inter-reader agreement for LI-RADS CT/MRI v2018 categorization and imaging features using individual participant data (IPD) meta-analysis for MRI and CT separately. STUDY TYPE: Retrospective meta-analysis. POPULATION: 805 patients (542 male, mean age 60.8 ± 11.6 [SD] years) at risk of HCC. FIELD STRENGTH/SEQUENCE: 1.5 and 3 T, Sequences varied across institutions but followed standard LI-RADS protocols. ASSESSMENT: Studies from the LI-RADS Living IPD Meta-Analysis Project were used. INCLUSION CRITERIA: observations evaluated by > 1 reader using LI-RADS CT/MRI v2018. Risk of bias was assessed for the index test domain using QUADAS-2; sensitivity analysis was conducted excluding high-risk observations. The developed protocol is available on the Open Science Framework (https://osf.io/tdv7j/files/6kh7s). STATISTICAL TESTS: . A post hoc univariable meta regression was conducted using the following variables: number of readers, reader experience, feature prevalence, and study country. Statistical significance was defined as two-tailed p < 0.05. RESULTS: Five studies (three CT and MRI, two MRI) comprising 975 observations were included. Four studies had two readers, and one had three, most readers were specialized abdominal radiologists (3-33 years' experience). Inter-reader agreement (κ) for major features was 0.21-0.74 on MRI and 0.11-0.75 on CT. For Ancillary features, κ was -0.02 to 0.68 for MRI and -0.02 to 0.58 on CT, and LR-M agreement was -0.07 to 0.58 on MRI and -0.07 to 0.66 on CT. LI-RADS categorization showed agreement of κ = 0.76 for MRI and κ = 0.50 for CT. DATA CONCLUSION: MRI consistently reported higher agreement than CT for shared features, but overall inter-reader agreement was variable. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 2: diagnostic accuracy, considered by most as clinical efficacy.