Congenital anomalies and variations of the bile and pancreatic ducts: magnetic resonance cholangiopancreatography findings, epidemiology and clinical significance

PURPOSE

The objective of this paper is to document the magnetic resonance cholangiopancreatography (MRCP) findings and the epidemiology of congenital anomalies and variations of the bile and pancreatic ducts and to discuss their clinical significance.

MATERIALS AND METHODS

Three-hundred and fifty patients of both sexes (150 females, 200 males, age range 0-76 years, average age 38 years) underwent MRCP for clinically suspected lithiasic, neoplastic or inflammatory disease of the bile and pancreatic ducts. Patients were imaged with a 1.5-T superconductive magnet (Magnetom Vision, Siemens, Erlangen, Germany), a four-channel phased-array body coil, breath-hold technique, with multislice T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE), MIP reconstructions, and a single-shot T2-weighted turbo-spin-echo sequence rapid acquisition with relaxation enhancement (RARE) with different slice thicknesses. Studies in oncological patients were completed with fat saturation 3D T1 gradient-echo sequences during the intravenous injection of gadolinium diethylene triamine pentaacetate acid (DTPA) (0.2 ml/kg).

RESULTS

MRCP demonstrated recurrent and therefore normal bile and pancreatic ducts in 57% of patients. In the remaining 42.3%, it documented anatomical variants (41%) and congenital anomalies (1.3%). Variants of the intrahepatic bile duct were seen in 21% of cases: crossover anomaly (6.7%), anterior branch of the right hepatic duct draining the IV and VII segments that flow together with the left bile duct (3.1%) and anterior and posterior branches of the right hepatic duct that flow together with the common hepatic duct (3.3%). Variants of the extrahepatic bile ducts were present in 8.8% of patients: low insertion of the cystic duct into the common hepatic duct (4.5%), emptying of the cystic duct into the right hepatic duct (2.7%) and a second-order large branch draining into the cystic duct (1.6%). MRCP identified a double gall bladder in 3% of patients and anatomical variants of the biliopancreatic system in 8.2%: pancreas divisum (5.2%) and a long sphincter of Oddi (3%). Finally, congenital anomalies were diagnosed in 1.3% of cases: bile duct cysts (0.3%), atresia of the bile ducts (0.3%) and multiple biliary hamartomatosis (0.7%).

CONCLUSIONS

The congenital anomalies and anatomical variants of the bile and pancreatic ducts present a complex spectrum of frequent alterations, which are worthy of attention in both the clinical and surgical settings and are readily identified by MRCP.