Three-dimensional computed tomography pancreatography of an annular pancreas with special reference to embryogenesis.

OBJECTIVES: Several hypotheses have been proposed to explain the embryogenesis of an annular pancreas. Three-dimensional (3D) imaging of the annular pancreas may be useful to elucidate the embryogenesis. The aim of this case report is to clarify the pancreatic ducts in the annular pancreas by 3D computed tomography pancreatography (3D-CTP), stereographically.

METHODS: Three-dimensional CTP under endoscopic retrograde pancreatography using a balloon catheter was performed with a helical CT scanner. Three-dimensional images of the pancreatic duct were obtained with simple threshold, shaped surface display.

RESULTS: Wirsung duct that surrounds the ventral side of the descending portion of the duodenum and Santorini duct that surrounds the dorsal side of the descending portion of the duodenum were reconstructed by 3D-CTP, stereographically, and the presence of an annular pancreas was confirmed. These findings suggest that the formation of the annular pancreas in the current case may be attributable not only to abnormal development of the right lobe of the ventral pancreatic bud, but also to overgrowth of the dorsal pancreatic bud toward the ventral aspect of the duodenum or excessive rotation of the duodenum following fusion of the ventral bud to the dorsal bud.

CONCLUSION: Three-dimensional CTP is expected to contribute usefully toward clarifying the embryogenesis of an annular pancreas.