Purpose: To analyze the CT and MR imaging features of circumportal pancreas (CP) with emphasis on the relative frequency of variants of parenchymal fusion, ductal anatomy, and vascular anatomy.
Methods: A retrospective review of CT and MR imaging findings of 40 patients with CP was performed. CT and MR images were reviewed by two radiologists in consensus. The course of the pancreatic duct in relation to the portal vein (anteportal vs. retroportal), location of the circumvenous pancreatic parenchyma in relation to the splenic vein (suprasplenic vs. infrasplenic), presence or absence of a visible accessory duct posterior to the portal vein, presence of vascular variants, history of pancreatitis and pancreatic surgery were recorded. Cases were classified into four categories: anteportal suprasplenic, retroportal suprasplenic, anteportal infrasplenic, and retroportal infrasplenic.
Results: One case of suprasplenic fusion was excluded from the classification due to non-visualization of the pancreatic duct. 32/39(82%) of cases were classified as anteportal suprasplenic, 2/39(5%) as retroportal suprasplenic, 4/39(10%) as anteportal infrasplenic, and 1/39(3%) as retroportal infrasplenic. There were 12 vascular variants including nine with an intraparenchymal course (through the pancreatic head) of the common hepatic artery, one with an intraparenchymal course of the right hepatic artery, two replaced right hepatic arteries from the superior mesenteric artery, and one with an intraparenchymal course of the left gastric vein.
Conclusion: Circumportal pancreas is an important pancreatic fusion anomaly with distinctive imaging features. The most common variant of CP is the anteportal suprasplenic subtype, with other subtypes being much less common. Intraparenchymal course of the common hepatic artery is a common variant associated with CP. Recognition of CP is important to avoid potential complications in patients who undergo pancreatic surgery.