Congenital variants and anomalies of the pancreas and pancreatic duct: imaging by magnetic resonance cholangiopancreaticography and multidetector computed tomography

Abstract

Though congenital anomalies of the pancreas and pancreatic duct are relatively uncommon and they are often discovered as an incidental finding in asymptomatic patients, some of these anomalies may lead to various clinical symptoms such as recurrent abdominal pain, nausea and vomiting. Recognition of these anomalies is important because these anomalies may be a surgically correctable cause of recurrent pancreatitis or the cause of gastric outlet obstruction. An awareness of these anomalies may help in surgical planning and prevent inadvertent ductal injury. The purpose of this article is to review normal pancreatic embryology, the appearance of ductal anatomic variants and developmental anomalies of the pancreas, with emphasis on magnetic resonance cholangiopancreaticography and multidetector computed tomography.

Keywords: Accessory pancreatic lobe; Annular pancreas; Congenital; Pancreas; Pancreas divisum.

Fig. 1

Drawings show normal embrologic development of pancreas. Ventral pancreatic bud (VP) arises from hepatic diverticulum, and dorsal pancreatic bud (DP) arises from dorsal mesogastrium (A). During 7th gestational week, expansion of duodenum causes ventral pancreatic bud to rotate and pass behind duodenum from right to left and fuse with dorsal pancreatic bud (B-D). Ventral bud forms posterior head and uncinate process, whereas dorsal bud forms anterior head, body, and tail. Finally, ventral and dorsal pancreatic ducts fuse, and pancreas predominantly is drained through ventral duct, which joins common bile duct at level of major papilla and dorsal duct drains at level of minor papilla.

Fig. 2

Drawings show variation in course of pancreatic duct. (A) Descending (B) vertical (C) sigmoid (D) loop shaped course.

Fig. 3

Magnetic resonance cholangiopancreaticography images reveal variation in course of pancreatic duct. A. Sigmoid shaped (arrow). B, C. loop shaped (arrows) course. CBD = common bile duct, D = duodenum, MPD = main pancreatic duct

Fig. 4

Drawings show variation in configuration of pancreatic duct. (A) Bifid configuration with dominant duct of Wirsung drainage, (B) bifid configuration with dominant duct of Santorini drainage without divisum, (C) rudimentary non-draining duct of Santorini (D) pancreas divisum, (E) ansa pancreatica.

Fig. 5

Magnetic resonance cholangiopancreaticography image reveals typical inverted-S shape of duct of Santorini (S) in ansa pancreatica. CBD = common bile duct, D = duodenum, MPD = main pancreatic duct, W = Wirsung

Fig. 6

Duplication of pancreatic duct. Magnetic resonance cholangiopancreaticography images (A, B) show focal duplication (arrows) of pancreatic duct. CBD = common bile duct, D = duodenum, GB = gall bladder, MPD = main pancreatic duct

Fig. 7

Magnetic resonance cholangiopancreaticography image reveals dominant dorsal duct (DD) with santorinicele (arrow) in pancreas divisum. D = duodenum

Fig. 8

Magnetic resonance cholangiopancreaticography image reveals long common channel (> 15 mm) (arrows) and associated Todani type 4a choledochal cysts with intrahepatic and extrahepatic components. CBD = common bile duct, MPD = main pancreatic duct

Fig. 9

Magnetic resonance cholangiopancreaticography image shows dorsal duct (DD) crossing anterior to common bile duct (CBD) and emptying separately into minor papilla and CBD joining with ventral duct (VD) and both entering into major papilla in patient with pancreas divisum. D = duodenum

Fig. 10

Pancreas divisum. Axial (A) and curved planar reformatted (B) MDCT images show dorsal duct (DD) crossing anterior to common bile duct (CBD) and emptying separately into minor papilla in patient with pancreas divisum. D = duodenum, P = pancreas, VD = ventral duct, MDCT = multidetector computed tomography

Fig. 11

Magnetic resonance cholangiopancreaticography image shows annular pancreatic duct (APD) communicating with main pancreatic duct (MPD) and completely encircling duodenum (D) in patient with annular pancreas.

Fig. 12

Axial MDCT image shows pancreatic tissue (arrows) completely encircling second part of duodenum (D) in patient with annular pancreas. P = pancreas, MDCT = multidetector computed tomography

Fig. 13

Axial MDCT image shows pancreatic tissue (arrow) extending in anterolateral direction to second part of duodenum (D) and dilatation of stomach (St) in patient with incomplete annular pancreas. P = pancreas, MDCT = multidetector computed tomography

Fig. 14

Axial MDCT image shows partial dorsal agenesis of pancreas (arrows) in patient with polysplenia syndrome. P = pancreas, J = jejunum, S = spleen, MDCT = multidetector computed tomography

Fig. 15

Accessory pancreatic lobe. Oblique axial (A) and fat suppressed contrast-enhanced T1-weighted gradient echo (B) MR images show accessory pancreatic lobe (arrows) that has similar attenuation and signal intensity to pancreatic tissue (P), arising from pancreas, projecting anteriorly and attaching to gastric duplication cyst (DC). P = pancreas, J = jejunum

Fig. 16

Variations of pancreatic contours. Axial MDCT (A) and T2-weighted MR (B) images show soft tissue protuberance (arrows) that has similar attenuation and signal intensity to pancreatic head (P). C = common bile duct, CBD = common biliary duct, D = duodenum, P = pancreas