Palak J. Trivedi

Summary Background Imaging markers of biliary disease in primary sclerosing cholangitis (PSC) have potential for use in clinical and trial disease monitoring. Herein, we evaluate how quantitative magnetic resonance cholangiopancreatography (MRCP) metrics change over time, as per the natural history of disease. Methods Individuals with PSC were prospectively scanned using non‐contrast MRCP. Quantitative metrics were calculated using MRCP+ post‐processing software to assess duct diameters and dilated and strictured regions. Additionally, a hepatopancreatobiliary radiologist (blinded to clinical details, biochemistry and quantitative biliary metrics) reported each scan, including ductal disease assessment according to the modified Amsterdam Cholangiographic Score (MAS). Results At baseline, 14 quantitative MRCP+ metrics were found to be significantly different in patients with PSC ( N = 55) compared to those with primary biliary cholangitis ( N = 55), autoimmune hepatitis ( N = 57) and healthy controls ( N = 18). In PSC specifically, baseline metrics quantifying the number of strictures and the number and length of bile ducts correlated with the MAS, transient elastography and serum ALP values ( p < 0.01 for all correlations). Over a median 371‐day follow‐up (range: 364–462), 29 patients with PSC underwent repeat MRCP, of whom 15 exhibited quantitative changes in MRCP+ metrics. Compared to baseline, quantitative MRCP+ identified an increasing number of strictures over time ( p < 0.05). Comparatively, no significant differences in biochemistry, elastography or the MAS were observed between timepoints. Quantitative MRCP+ metrics remained stable in non‐PSC liver disease. Conclusion Quantitative MRCP+ identifies changes in ductal disease over time in PSC, despite stability in biochemistry, liver stiffness and radiologist‐derived cholangiographic assessment (trial registration: ISRCTN39463479).