Dynamic study of pancreaticobiliary reflux using secretin-stimulated magnetic resonance cholangiopancreatography in patients with choledochal cysts.

BACKGROUND/PURPOSE: Refluxes through pancreaticobiliary maljunctions play an important role in the pathophysiology of choledochal cysts. Dynamic studies of the pancreaticobiliary tract were performed using secretin-stimulated magnetic resonance cholangiopancreatography. METHODS: Six patients with choledochal dilation were recruited for this study. Four patients exhibited cystic and 2 exhibited fusiform dilatation of the common bile duct (CBD). Magnetic resonance cholangiopancreatography images were obtained every minute during the 15-minute period after secretin stimulation. The sequential morphological changes in the biliary trees, pancreas, and duodenum were assessed, and the total pixel values of these organs were measured for each image, then plotted as a ratio against the baseline image. RESULTS: In 2 cases involving cystic dilatation, the intensity of bile duct images continued to rise after secretin stimulation. In a case involving fusiform dilatation, a transitory elevation in CBD intensity was observed. In 3 cases involving fusiform or cystic dilatation, the intensity of CBD did not change notably. In all cases, the duodenum was filled well after secretin stimulation. CONCLUSIONS: The sustained elevation in bile duct intensity after secretin stimulation indicates reflux and bile stasis. Transitory elevation may indicate reflux without stasis. This method allows assessment of the dynamics of pancreatic and bile fluid under more physiologic condition.