| Background With the development of science and technology, especially the maturity of imaging technology, surgery, especially hepatobiliary surgery entered into a new digital era, also a "precise surgery" era. These advancements could not only provides the basic data of further research in living donor liver transplantation, extracorporeal hepatectomy and autologous liver transplantation and other difficult surgery, but also some possible strategies for massive hepatic tumors. In recent years, with the development of three-dimensional reconstruct technology and analysis, more and more surgeons realized and focused on the anatomical specificity and difference between three-dimensional and two-dimensional liver level, especially the variations in perihilar and segmental portal veins and bile ducts. And these could also change some traditional surgery conceptions, and increase the opportunity of complicated procedures. However, the two-dimensional imaging test in hepatic vein system still own its defects which may effects the decision of pre-operation and benefits of patients. And the three dimensional reconstruction can precise display the morphology of all kinds veins and their drainage volume, finally benefits the patients. As such researches were not comprehensive, it is necessary to make a further and systemic discussion.Objectives To carry on a comprehensive study with the assistance of the three dimensional imagine technique on the variations of hepatic veins, and their significance in the hepatobiliary surgery, and to explore the importance and difference of some accessory veins with the major hepatic veins in the classical liver anatomy.Methods This was a retrospective study of MSCT of 98 consecutive patients with no cirrhosis or malignant tumors. IQQA-Liver software was used to display and analyze three-dimensional (3D) images of the hepatic veins and their branches, variations and drainage volume.Results 98 consecutive adults [52 women,46 men; mean age:55.33±11.32 years (range,25-77 years)] who underwent hepatic CT at the Chinese PLA General Hospital (Beijing, China) were analyzed with 3D imaging software (IQQA-Liver, EDDA Technology Inc., Princeton, NJ, USA). Patients with severe cirrhosis and other tumors which can affect the morphology of hepatic veins were excluded. The average liver volume was 1272.65±322.04 ml; the left hepatic veins drained the smallest parts (266.89±94.51 ml,21.13±5.41%) of the liver compared with the right (443.51±190.27 ml,35.58±12.41%) and middle hepatic veins (445.53±173.71 ml,34.64±8.76%). The most common pattern around the second hepatic hilus was that the left hepatic veins shared a common trunk (12.54±4.29 mm) with the middle hepatic veins in 51cases (52.0%). Besides, the visualization rate of one or more inferior right hepatic veins (IRHVs) was 43.9%. Based on Nakamura and Tsuzuki’s classification, we classified the RHV and IRHV into three types based on the size of the IRHVs compared with that of the RHVs.55 patients (56.1%) with type I RHV had no obvious IRHV,36 (36.7%) with type II had a small IRHV (IRHV< RHV), and 7 with type III (7.1%) had a large IRHV (IRHV≥RHV). The average diameter of the IRHV in our study was 4.65±1.14 mm, and the average drainage volume was 179.27±128.79 ml (14.0±9.18%, range 21.20-618.20 ml). In 11.2% of patients, the drainage volume for the IRHV was larger than for the right hepatic vein (RHV). There was a positive correlation between the diameter of the IRHVs and the drainage volume (y=80.388x-194.268, r=0.709, p<0.01). In addition, we found that the IRHV diameter increased from type I to type Ⅲ and was inversely related to the RHV drainage territory.The patterns of the left hepatic and middle hepatic veins were also observed and classified. The MHV observed in all 98 patients were divided into four distinct variants:A. one trunk with two bifurcations (one bifurcation confluence in the middle of the trunk and the other in the distal of the main trunk); B. one trunk with one bifurcation that sometimes had obvious segment 4 or segment 8 veins at the initial part of the MHV; C. two separate trunks terminating at the IVC directly, and D. a large single MHV without receiving major subsegment tributaries. The incidences of them were 61.2%,24.5%,7.1% and 7.1%, respectively. The variations of LHV were also four types:A. one main trunk formed by segment 2 and 3 veins around the umbilical fissure, sometimes with segment 4 veins or UHVs at the beginning part of the trunk (55.1%); B. two separate large veins that each drained an individual segment without uniting before draining into the IVC (23.5%); C. a single vessel that received no significant tributaries (12.2%), and D. a radial type without a major trunk (10.2%).Umbilical hepatic veins appeared in 75 cases (76.5%), and anterior fissure hepatic veins appeared in 74 cases (75.5%).The rate of the presence of a separate segment 4 vein was 15.3%, and 77 patients had obvious superficial veins. The rate of the presence of an accessory hepatic vein that drained the caudate lobe was 22.4%.Conclusion The variation rates of hepatic veins are higher than the portal vein of perihilar region, and the incidence of inferior right hepatic veins could reduce the drainage volume of right hepatic veins and change the surgery strategies. A separate segment 4 vein would drain a considerable volume of liver. In addition, the classification of MHV, LHV and the incidence of AFV and UFV were significant during the hemihepatectomy and other complicated operations. Therefore, the three dimensional reconstruction technology could offered more detailed information about the anatomical features and variations of hepatic venous veins in Chinese people and these will assist in more precise liver surgeries. |
