Magnetic resonance cholangiopancreatography for suspected cholangiopathy in children and young adults: a multi-reader agreement study

Background: Magnetic resonance cholangiopancreatography (MRCP) is used to diagnose and monitor primary sclerosing cholangitis (PSC). Objective: To assess inter-reader agreement for the diagnosis of PSC/autoimmune sclerosing cholangitis (ASC) and for individual MRCP features of cholangiopathy in a pediatric sample. Materials and methods: This was a retrospective, IRB-approved study that included MRCP examinations from patients <21 years old with known or suspected cholangiopathy. Multiple biliary and hepatic imaging features were assessed independently by nine pediatric radiologists using 2D and 3D MRCP images. Kappa (κ) statistics and intra-class correlation coefficients (ICC) with 95% confidence intervals (CI) were used to measure inter-reader agreement. Results: Seventy-five patients were included (median age=16.8 [IQR 13.8-18.7] years; 48 boys); 22.7% (17/75) had PSC, 22.7% (17/75) had ASC, and 54.7% (41/75) had other diagnoses. Among observers, agreement was only slight for presence of cholangiopathy (κ=0.15 [95% CI 0.07 to 0.23]) and presence of PSC/ASC (κ=0.13 [0.06 to 0.21]). Agreement was poor for categorical intrahepatic stricture number (κ=-0.002 [(-0.16 to 0.15]) and stricture extent (κ=-0.06 [-0.09 to-0.02]). Agreement was slight for presence of intrahepatic stricturing disease (κ=0.08 [0.04 to 0.12]). Most other findings had fair agreement between readers (including intrahepatic focal dilations, intrahepatic and extrahepatic diverticula, diffuse extrahepatic dilation without stricture, bile duct mural thickening, and biliary obstruction [κ=0.22 to 0.34]). There was moderate agreement for categorical extrahepatic stricture length (κ=0.46 [-0.11 to 1]) and presence of extrahepatic biliary dilation (κ=0.53 [0.40 to 0.65]). There was excellent agreement for extrahepatic bile duct maximum diameter (ICC=0.89 [0.85 to 0.92]). Conclusion: Inter-reader agreement for interpreting MRCP in children and young adults is slight to fair for the diagnosis of PSC/ASC and for most findings of cholangiopathy.