Background: The prevalence of PSC in patients with UC and normal liver function tests is unknown. This prospective study sought to clarify the prevalence and characteristics of biliary abnormalities consistent with PSC on magnetic resonance cholangiography (MRC) in UC patients with normal liver function, and to evaluate evidence of disease progression and complications during long-term follow-up.
Methods: In phase one, 51 patients with extensive UC and normal liver function tests underwent MRC and blood evaluation. 28 age and sex-matched healthy volunteers and 28 patients with an established diagnosis of PSC and cholestatic liver function had MRC evaluation as negative and positive controls, respectively. In phase two, 19 patients with extensive UC and colorectal dysplasia (CRD) identified from colonoscopic surveillance, and 24 negative and positive matched controls underwent MRC evaluation. Two independent specialist radiologists blinded to clinical details interpreted MRC scans. Clinical outcome was assessed prospectively at outpatient clinic with liver biochemistry, endoscopic surveillance and abdominal imaging as indicated.
Results: 7/51 UC patients (14%) and 4/19 UC patients with CRD (21%) and normal liver function had biliary abnormalities on MRC consistent with PSC. Over half (7/11; 55%) had intrahepatic duct involvement only. The presence of biliary abnormalities was associated with quiescent disease (p=0.03) and negative smoking history (p=0.03) on multivariate analysis. Inter-observer (κ=0.88) and intra-observer (κ=0.96) agreement by radiologists for MRC interpretation was good, with 100% of positive PSC controls identified correctly. During a median follow-up of 8.8 years (range 30–116m), 4/11 patients (36%) with biliary abnormalities on MRC developed persistently abnormal liver function and 2/11 patients (18%) had radiological evidence of progression of PSC. 1/7 patients (14%) with extensive UC and biliary abnormalities developed a low-grade adenoma on colonoscopic surveillance that was endoscopically resected, and 1/4 patients (25%) with UC and CRD developed a cholangiocarcinoma (CCA) after 7.2 years. 2/11 patients died.
Conclusions: Unsuspected biliary abnormalities consistent with PSC were present in 14% of extensive UC patients, and 21% UC patients with CRD, and normal liver function. During 9 year follow up, a third developed abnormal liver function, a fifth developed progressive ductal disease, and one developed CCA. MRC may be appropriate in patients with extensive UC regardless of liver function, to identify subclinical PSC and stratify surveillance strategies. This is especially important in those with UC and CRD, with an increased risk of PSC and development of CCA.