The Branching Pattern of the Inferior Pancreaticoduodenal Artery in Patients with a Replaced Right Hepatic Artery.

: Understanding the anatomy of the inferior pancreaticoduodenal artery (IPDA) is important in patients undergoing pancreaticoduodenectomy, especially in an artery-first approach, resulting in some studies focusing on IPDA anatomy. However, the studies have covered only cases without variation in hepatic arterial anatomy, a common arterial variant, suggesting the necessity of the investigation of IPDA anatomy in cases with the variant. Using images of multidetector row computed tomography, cases with replaced right hepatic artery (rRHA) were picked out among 714 patients undergoing multidetector row computed tomography for determining arteries of the pancreatic head at our institution. IPDA branching pattern was investigated in the rRHA cases. Three-dimensional reconstruction was performed to visually understand the branching pattern in representative cases. rRHA was identified in 139 cases (19.5%); rRHA originating from the superior mesenteric artery (SMA) (type 1; 74.1%), celiac axis (type 2; 18.0%), and others (type 3; 7.9%). IPDA branching pattern was categorized; IPDA originated from SMA (type A), posterior and anterior IPDA originated from rRHA and SMA, respectively (type B), or IPDA originated from rRHA (type C). Of type 1 cases, 69, 23, and 11 cases showed type A, B, and C pattern, respectively. Of type 2 cases, 16 and 9 cases showed type A and B, respectively. All 11 type 3 cases showed type C. IPDA branching pattern was determined in the rRHA cases. This would help identification of rRHA cases where the artery-first approach is technically less feasible at pancreaticoduodenectomy (type 1-B, 1-C, and 2-B).