Secretin-stimulated MR cholangiopancreatography: spectrum of findings in pancreatic diseases

MR cholangiopancreatography (MRCP) is an imaging technique that has evolved over the past 2 decades and that continues to have a fundamental role in the non-invasive detection of morphologic features of the pancreatic ducts. In several studies, MRCP has shown a good correlation with endoscopic retrograde cholangiopancreatography in the evaluation of diseases and anatomic variants of the pancreatic ductal system. However, in physiologic conditions the pancreatic ducts are not always easily recognisable. More recently, secretin-enhanced MRCP protocols have been developed for a more complete assessment of pancreatic ducts and glandular function, including monitoring of pancreatic flow dynamics and duodenal filling after pancreatic hormonal stimulation with secretin. The injection of this hormone causes temporary dilation of the pancreatic ducts, principally by increasing pancreatic exocrine secretions, and thus improving MRCP detection of the ducts and characterisation of pancreatic disorders and allowing the assessment of the exocrine pancreatic reserve. The purpose of this pictorial review is to summarise the technical aspects of secretin-stimulated MRCP, to report the secretin-stimulated MRCP findings of pancreatic duct abnormalities and to review the diagnostic capabilities of secretin-stimulated MRCP in various pancreatic ductal system conditions. MAIN MESSAGES • MRCP has a fundamental role in the non-invasive detection of pancreatic ducts. • In physiologic conditions pancreatic ducts are not always well detected on MRCP. • Secretin injection causes temporary dilation of pancreatic ducts and thus improves MRCP detection. • Secretin-stimulated MRCP may allow the assessment of the exocrine pancreatic reserve. • Secretin increases the diagnostic capabilities of MRCP for evaluating pancreatic disorders.