Objective    To assess whether the Couinaud’s segmengtation of the liver in transaxial imaging is an accurate indicator of hepatic segment with 16-slice spiral CT hepatic portography and venography.     Methods    One hundred healthy subjects underwent 16-slice spiral CT hepatic portography and venography. Three-dimensional maximum intensity projection (MIP) and volume rendering (VR) of the portal and hepatic venous structures were created. The portal and hepatic vein branches were observed and the relationship between portal and hepatic veins was evaluated with tracking the branches of portal vein.     Results    Segmental branches of portal vein supplied correspondingly hepatic segment

and hepatic vein and its branches located between adjacent hepatic segments. Branches of portal vein could cross the adjacent hepatic vein. The boundaries of hepatic segments were not simple straight lines or flat planes.     Conclusion    Couinaud’s segmengtation of the liver in transaxial imaging has limitations. Three-dimension (3D) angiography of portal and hepatic venous systems can be applied to divide hepatic segment accurately. Hepatic segment analyzed by tracking the branches of portal vein is of more clinical value.