Intrahepatic Venous Anato my on Three-Dimensional Spiral CT during Arterial Portography

Purpose: To evaluate the intrahepatic anatomy of the hepatic vein and right portal venous system, as seen on 3-D CTAP, and to assess the avascular zone between the anterior and posterior segments of the right lobe in relation to the right hepatic vein. Materials and Methods: Fifteen patients in whom nodular hepatocellular was suspected underwent spiral C-TAP. 3-D images of the portal and hepatic vein were obtained using the maximal intensity projection technique. We examined the portal venous branching pattern and the draining pattern of the hepatic venous system to the inferior vena cava, as well as variation of the right hepatic vein and the avascular zone between the anterior and posterior segments of the right lobe. Results: In 13 patients, three hepatic veins were clearly visualized, and in ten, the middle and left hepatic veins conjoined before draining to the IVC. In three patients, three hepatic veins drained separately into the IVC. Two right hepatic veins were seen in three patients. The right portal venous system was clearly visualized in 13 patients a classical branching pattern in 11, trifurcation in one, and four simultaneous branching patterns in one. Lateral projection showed that the angle of the avascular zone declined posteriorly by 26- 64( 47.5) in relation to the right hepatic vein. Conclusion: We observed the drainage pattern of the hepatic vein and variation of the right portal venous system on 3-D image, and confirmed that since the avascular zone declined posteriorly, the right hepatic vein is an inappropriate landmark for right hepatic segmentation.