The role of imaging in determining prognosis for primary sclerosing cholangitis: A systematic review

Background/Aims: Primary sclerosing cholangitis (PSC) is a chronic, progressive, fibrotic bile duct disease. Resultant complications include infection, progressive liver disease and cancer. While diagnosis relies extensively on imaging, the role of imaging in determining prognosis is unclear. The aim of this study was to systematically review existing imaging indices and features that predict PSC progression. Materials and Methods: We performed a systematic review of imaging features that predict PSC progression. PubMed, EMBASE, MEDLINE, Clinicaltrials.gov and the Cochrane Library were searched from inception to November 2018 for relevant studies. Pertinent data were extracted and assessed. Study quality was evaluated using the Newcastle-Ottawa scale (NOS). Results: The search returned 2504 results. Nine studies were included in the final review. Four studies evaluated the prognostic value of imaging features and five evaluated prognostic algorithms. The mean NOS score was 4.44 ± 0.98 on a scale of 0 to 9. Imaging features that were of prognostic value were degree of intrahepatic duct narrowing, the presence of a dominant biliary duct stricture and percentage of narrowed intraheptic ducts. Three imaging indices (one endoscopic retrograde cholangiopancreatography (ERCP)-based and two magnetic resonance-based) had been derived. The ERCP index was validated in a second cohort and subsequently updated to improve its predictive ability. The magnetic resonance cholangiopancreatography (MRCP) index was validated in two studies and was found to be predicative of transplant-free survival. A modified MRCP index (MRCP-risk score) was evaluated in a prospective multicenter study and was found to be predicative of PSC-related disease progression. Conclusion: In conclusion, ERCP and MRCP-based indices have short-term prognostic value in PSC. However, more studies are required to validate their predictability of disease-related progression, such as liver decompensation, ascending cholangitis, cholangiocarcinoma and liver transplantation.