Variations in the intrahepatic portions of the hepatic and portal veins: Findings on helical CT scans during arterial portography

OBJECTIVE. The goals of this study were to describe variations in the intrahepatic portions of the hepatic and portal veins as visualized by helical CT during arterial portography (CTAP) and to examine the surgical implications of these findings. MATERIALS AND METHODS. A retrospective review of 69 helical CTAP scans of 69 patients with small hepatic tumors and no evidence of vascular invasion or distortion was done. Axial helical CTAP scans were reviewed to determine the presence, number, and location of intrahepatic portions of the hepatic and portal veins. RESULTS. Among the 60 patients (87%) in whom the right, middle, and left hepatic veins were visualized, 19 (32%) had supernumerary hepatic veins. Right inferior hepatic veins were found in six (9%) of the 69 patients. Variations in intrahepatic portal anatomy were found in four patients (6%) and involved an immediate trifurcation of the portal vein in three patients (4%) and a left main portal vein originating from the right anterior portal branch in one patient (2%). CONCLUSION. Variations in the intrahepatic portions of the hepatic and portal veins are frequently seen on helical CTAP scans. Recognition of such variations is important in the preoperative evaluation of patients with hepatic tumors because these variations may have implications for tumor resection and for planning the operative approach.