Posterior aspect of hepatic segment IV: patterns of portal venule branching at helical CT during arterial portography.

Abstract

To determine the anatomy of the portal venous system in the posterior aspect of segment IV of the liver by using helical computed tomography (CT) during arterial portography (CTAP). One hundred consecutive patients underwent CTAP. Helical CT during hepatic arteriography was performed in 20 patients. In seven patients with hepatocellular carcinoma in the posterior aspect of segment IV, the feeding arteries were also analyzed. A venule from the intrahepatic portal vein to segment IV was seen in all patients. Other findings included a tiny venule from the distal part of the main left portal vein (n = 36), from the proximal left main portal vein (n = 20), and from the right portal vein (n = 18). Aberrant right gastric venous drainage and/or parabiliary venous drainage directly into the posterior aspect was present in 14 patients. In two patients, a tiny accompanying artery was seen on images from CT during hepatic arteriography. In seven patients with hepatocellular carcinoma, the main feeding artery branched from the right (n = 2) or left (n = 5) hepatic artery. CTAP adequately demonstrates the tiny portal venous and arterial branches from the main right or left portal vein that distribute to the posterior aspect of segment IV. Knowledge of this vascular anatomy is clinically important.