Cystic duct drainage into hepatic ducts: a primary study using three dimensional magnetic resonance cholangiopancreatography

Objective To study the pattern of cystic duct (CD) drainage into hepatic ducts (CDIHD) by using three dimensional magnetic resonance cholangiopancreatography (3D MRCP) combined with conventional MRI sequences. Methods Thirty-eight patients with CDIHD were studied retrospectively and they served as the observation group. Another 38 patients who had no CDIHD were selected randomly and they served as the control group. The hepatic bile duct where the CD drained in the observation group, the site where the common hepatic duct (CCHD) started, and the types of the intrahepatic bile duct (IHBD) in the two groups were analyzed. The types of the IHBD were classified according to the modified Couinaud's criteria. Results There were 26 patients who had their CD draining into the right liver bile ducts, 9 into the incomplete common hepatic duct, and 3 into the left hepatic duct in the observation group. For the types of IHBD in the observation/control groups, type A was observed in 15/19 patients, type B in 0/6, type C in 22/1, type D in 0/9, type E in 0/2, and type F in 1/1, respectively. The differences were significant (P<0.05). The number of patients who had their CCHD starting in the porta hepatis, superior duodenal bulb, posterior duodenal bulb, and pancreatic head in the observation/control groups, were 1/36, 19/2, 17/0, 1/0, respectively. The differences were also significant (P<0.05). Conclusion In patients with CDIHD, CD most commonly drained into the right hepatic duct. Patients with CDIHD had a different IHBD type, and the IHBD confluence was lower. Key words: Magnetic resonance cholangiopancreatography (MRCP); Cystic duct; Intrahepatic bile duct; Common hepatic duct; Anatomy variation