MRCP of Congenital Pancreaticobiliary Malformation

Abstract

Background and Aims: MRCP is one of the first choices for investigating and diagnosing pancreaticobiliary diseases noninvasively. We compared the accuracy of conventional MRCP and ERCP in making the diagnosis of congenital pancreaticobiliary malformations. Methods: In patients with pancreas divisum (n = 17; complete, n = 15 and incomplete, n = 2), pancreaticobiliary maljunction (n = 12), choledochocele (n = 2) and annular pancreas (n = 1) who underwent both ERCP and MRCP, the diagnostic accuracy and findings on MRCP were compared with those on ERCP. Results: Of the 32 patients with congenital pancreaticobiliary malformations diagnosed on ERCP, 23 (72%) patients could also be diagnosed on MRCP. Of the 15 patients with complete pancreas divisum, 11 could be diagnosed on MRCP based on the finding of a dominant dorsal pancreatic duct crossing the lower bile duct and emptying into the duodenum without communicating with the ventral pancreatic duct. The dorsal pancreatic duct was identified in all patients, but the ventral pancreatic duct was not identified in 8 patients, 5 of whom had a narrow and short ventral pancreatic duct up to 2 cm long on ERCP. Of the 4 patients who could not be diagnosed as having complete pancreas divisum on MRCP, the relationship between the dorsal pancreatic duct and the lower bile duct was unclear in 3, and a long inferior branch from the dorsal pancreatic duct crossed the short ventral pancreatic duct in 1 patient. In 2 patients with incomplete pancreas divisum, dominance of Santorini's duct could be suspected but the precise configuration of the filamentous connecting branch remained unclear. Of the 12 patients with pancreaticobiliary maljunction, 9 were diagnosed on MRCP based on findings of an anomalous union between the common bile duct and the pancreatic duct, as well as a long common channel. In 3 patients in whom the MRCP diagnosis of pancreaticobiliary maljunction could not be made, the formation of a long common channel could not be depicted on MRCP. In these 3 patients, the measured length of the long common channel on ERCP was 13 mm, 13 mm, and 15 mm, respectively. The 2 patients with choledochocele were also diagnosed on MRCP based on the presence of cystic dilatation of the lower bile duct. One patient with an annular pancreas was also diagnosed on MRCP based on the presence of an annular pancreatitis. Conclusions: Conventional MRCP is a useful, noninvasive tool for diagnosing congenital pancreaticobiliary malformations and the diagnostic accuracy can be increased with 3D-MRCP or dynamic MRCP with secretin stimulation.