Magnetic resonance cholangiography in the diagnosis of dominant strictures in pediatric-onset primary sclerosing cholangitis

Magnetic resonance cholangiopancreaticography (MRCP) has become the primary imaging modality in primary sclerosing cholangitis (PSC). Endoscopic retrograde cholangiopancreaticography (ERCP) is recommended when a dominant stricture (DS) of bile ducts is suspected in MRCP. However, MRCP criteria for DS are lacking. To evaluate the diagnostic accuracy of MRCP in the diagnosis of DS in patients with pediatric-onset PSC. ERCP and MRCP images of patients with pediatric-onset PSC (n=36) were evaluated for the presence of DS applying the diameter-based ERCP criteria. The diagnostic accuracy of MRCP in detecting DS was calculated using ERCP as the gold standard. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and accuracy of MRCP for detecting DS were 62%, 89%, 5.6, 0.43, and 81%. Most common reasons for incongruent ERCP/MRCP assessment were (1) MRCP stenosis not fulfilling the diameter criteria of ERCP, resulting in false negative MRCP evaluation, and (2) lack of filling pressure in MRCP, resulting in false positive MRCP evaluation. The high positive likelihood ratio of MRCP in detecting DS suggests that MRCP is a useful tool in the follow-up of PSC. However, diameter limits of DS should probably be less strict in MRCP than in ERCP.