A reliability study - strong inter-observer agreement of an expert panel for intestinal ultrasound in ulcerative colitis.

De Voogd, Floris; Wilkens, Rune; Gecse, Krisztina; Allocca, Mariangela; Novak, Kerri; Lu, Cathy; D'Haens, Geert; Maaser, Christian

BACKGROUND Intestinal ultrasound (IUS) is a promising and non-invasive cross-sectional imaging modality in the diagnosis and monitoring of ulcerative colitis (UC). Unlike endoscopy, where standardized scoring for evaluation of disease activity is widely used, scoring for UC with IUS is currently unavailable. Therefore, we conducted a study to assess reliability of IUS in UC among expert sonographists in order to identify robust parameters. METHODS Thirty patients with both clinically active (25) and quiescent (5) UC were included. Six expert sonographers first agreed upon key IUS parameters and grading including bowel wall thickness (BWT), Color Doppler Signal (CDS), inflammatory fat (i-fat), loss of bowel wall stratification (BWS), loss of haustrations and presence of lymph nodes. Thirty video-recorded cases were blindly reviewed. RESULTS Inter-observer agreement was almost perfect for BWT (ICC: 0.96) and substantial for CDS (κ=0.63). Agreement was moderate for presence of lymph nodes (κ=0.41) and fair for presence of i-fat (κ=0.36), BWS (κ=0.24) and loss of haustrations (κ=0.26). Furthermore, there was substantial agreement for presence of disease activity on IUS (κ=0.77) and almost perfect agreement for disease severity (ICC: 0.93). Most individual parameters showed strong association with IUS disease activity as measured by the 6 readers. CONCLUSION IUS is a reliable imaging modality to assess disease activity and severity in UC. Important individual parameters like BWT and CDS are reliable and could be incorporated in a future UC scoring index. Standardized acquisition and assessment of UC utilizing IUS with established reliability is important to expand the use of IUS globally.