Perfusion and drainage difference in the liver parenchyma: Regional plane in segment 6

The differences between the perfusion areas of portal vein and the drainage areas of hepatic vein result in the occurrence of either ischemic or congested areas after liver resection. To elucidate which factors are related to the differences between these areas of segment (S) 6 were therefore investigated. The portal-vein-based and hepatic-vein-based regional planes of S6 were defined using the region-growing and Voronoi tessellation methods in 103 consecutive patients who undergo liver resection. Finally, factors related to the difference between the perfusion and drainage areas of S6 were identified. The S6 regional plane based on the portal was coincident with that of hepatic veins (non-difference group) in 57 patients (55.3%), but was discordant on the ventral side (S6-dominant group) in 43 patients (41.7%) and the dorsal side (S5-dominant group) in 3 patients (3.0%). The presence of a proximal branch of the first portal 6 (S6-dominant group vs. non-difference group, 72.1% vs. 17.0%, p < 0.001) and the presence of an inferior right hepatic vein (S6-dominant group vs. non-difference group, 72.1% vs. 43.9%, p = 0.008) suggested large S6 ventrally. The median volume difference between the perfusion area of the portal vein and drainage area of the hepatic vein in S6 was 73 mL (range: 29-189 mL). In conclusion, preoperative 3D-simulation may enhance the preciseness of anatomic liver resection.