Primary sclerosing cholangitis (PSC) is a chronic progressive biliary disease that affects approximately 1200 patients in the Netherlands and around 80,000 in the Western world. It is often accompanied by ulcerative colitis (UC) or Crohn's disease affecting the large bowel. The cause of PSC is unknown, there is no medical therapy available that has proven to halt disease progression and the median time until death or liver transplantation is 13-21 years.

Diagnosis is made by magnetic resonance cholangiography (MRC), or in the case of so called small duct disease by liver biopsy.

Due to the heterogeneous disease course and the relatively low clinical event rate of 5% per year it is difficult to predict prognosis of individual patients or to recommend any surveillance strategy for malignancies. Also, the lack of surrogate endpoints impedes performing clinical research. Recently, two new post-processing tools have been developed to characterize and quantify abnormalities in the biliary tree as well as excretory function captured by MRC. These tools called MRCP+ (quantitative magnetic resonance cholangiopancreatography +) and LiverMultiscan (LMS) hold the prospect of adequately depicting and quantifying lesions of the biliary tree as well as capturing functional derailment. However, several features must be tested before the utility of this tools in clinical patient care can be concluded. Therefore, the aim of this study is to investigate the utility of these novel techniques in monitoring disease activity by performing consecutive annual MRI's.

Inclusion Criteria:

• Established PSC diagnosis according to the IPSCSG definitions
• Age ≥ 18
• Able to give informed consent

Exclusion Criteria:

• Post LTx
• Known allergy for MRI contrast agents, implants non-compatible with MRI or extreme claustrophobia causing discontinuation of MRI studies.

After publication, the following documentation can be requested by qualified research groups:

- Study protocol, statistical analysis plan and the clinical study report can be provided if a proper request is submitted.

IPD will contain decoded and only essential data for the objective of this study. Data that will be available for sharing purposes will only include decoded demographic data. Furthermore, MRCP+ data that underlies the results in the publication will be available for sharing, e.g. MRCP+ metrics

Until 5 years after publication

Data sharing can be requested by qualified research groups. Requests will be evaluated by the following method:

The request is supposed to contain a clear objective and methodology. E.g., it must contain the objective to explore or validate the value of MRCP+ and LMS techniques. Furthermore, the study proposal could, for example, be a systematic review or meta-analysis.

The request will be reviewed by a dedicated research team of the CATCH-IT-study. This research team contains the PI, PhD student, involved gastro-enterologist and radiologist and representative of Perspectum Ltd.

If the request seems valid and the credibility of the requesting party is validated, data sharing agreement will be developed with the local research support team. To submit a request, contact t.e.middelburg@amsterdamumc.nl