Computer-assissted3D Clinical Anatomy Research Of Perihilar And Segmental Portal Vein And Bile Ducts

Background Precise anatomy knowledge must be conducted before precise surgery.Recent years, with the rapid development of science and technology, liver surgery hasentered the era of “Precise Liver Surgery”. Surgeons need to have deep command ofanatomy on perihilar region and segmental horizon to perform the most complicatedprocedures, such as living donor liver transplantation, anatomical segmentectomy/subsegmentectomy, radical resection of hilar cholangiocarcinoma and major liverresection for congenital bile ducts dilation. However, studies in recent years on regionalliver anatomy are basically conducted by the methods of cadaveric liver or2D imaging,which are either in conformity with the clinical application habit or lack of contrast with3D models. Therefore, the results are not convincing enough. So far, it is still lack ofsystemic study on segmental vessels. In addition, according to recently researchingresults, many of the intrahepatic portal vein structure does not fully comply with thetraditional Couinaud segments, so it is necessary to take further discussion on thisquestion.Aim To carry on a systemic study on the perihilar and segmental portal veins and bileducts, and on the anatomical relationship of surgical significance in between, and todiscuss the development and significance of Couinaud’s segmentation.Methods The research involved consecuative128obstuctive jaundice cases in ourhospital, and MSCT of these cases were analysed. Liver, portal vein and biliary tractwere reconstructed3-dimensionally using Intrasense Myrian. The researcher observedthe region of interest with2D images combined3D models.Result28cases were excluded accoding to our criteria, and100cases were enrolled inthis study, among which73male and27female, mean age58.2±12.9yrs. The variationrate of portal vein in hilar region is was21%. The occurance rate of typical branch form (Type A), trifurcation type (Type B), I-shaped type (Type C), and other rare types (TypeD) was79%,9%,9%and3%respectively. P2had1to3branches, where1branch typetook92%and always originated from Rex Recess; Among2-3branches type, thebranches may originate from the left margin of UP. P3has1to4branches, where1branch type took88%and its original point was LPV cystic portion. Multi-branch typeP3might originate from the left (10%), ventro-caudal(1%) or cranial-dorsal (1%)margin of UP. P4could be divided into P4a and P4b, with1to3branches respectively(88%,89%). P4a and P4b originated seperately or jointly, with a frequency of53%and47%respectively; P4always originated from LPV cystic portion, but there might bebranches originated from cranial dorsal (31%) and the right side (17%) of the UP. P5comprised mostly2-4branches (87%), originated from RAPV. Ectopic originations ofP5include RPPV trunk (57%), P8v (54%), P8d or P8l (11%) and RAPV/RPPVbifurcation (7%). P8could be divided into P8v (100%), P8d (100%), P8l (73%) andP8m (49%).85%of P8d extended to the dorsal part of RHV. RPPV trunk was absent in12%of the cases. Besides the variation, the RPPV trunk could be divided into threetypes, which are arcuate type (62.5%),2-branch type (28.4%) and feather-shaped type(8.0%). Segmental anatomy of portal vein does not obey traditional Couinaudsegmentation strictly. The most common variations are1) P8d extended to the dorsalpart of RHV, where belongs to S7and2) the branches of P5originate from RPPV trunk(57%) and P8v (54%).The variation rate of perihilar bile ducts was36%. The occurrence rate of typicaltype (type A), trifurcation type (type B), RASD/RPSD low converging type (type C),RASD/RPSD converging into LHD type (type D) and rare type (type E) was64%,9%,2%,17%and8%respectively. The overall variation rate of left biliary system was56%. In75%cases, B2and B3converge to form the main trunk of LHD as the classicalanatomy. And in other25%cases, B4converge into B3prior to B2, as the variation. B4could be divided into B4a and B4b, among which66%form the trunk and34%did not. Onishi typeⅠ, Ⅱ, Ⅲ of the convergence was17%,72%and11%, respectively. Theoverall variation rate of right biliary system was85%. The most common variation wereB5branch converging into RPSD (61%), B8branch converging into RPSD (14%),RASD trunk absent (13%) and accessory hepatic duct (5%). The occurrence rate ofinfrapotal type in B3and RPSD was4%and18%respectively. All of the type C2andD1type bile ducts were infraportal type. The features of infraportal type bile ducts in2D images (continuous analysis from head to feet) were1) occurred in RAPV-RPSD-RPPV order;2) long RPSD trunk paralleled with RPV trunk. According to portal veinform, the proportion of infraportal bile ducts in A, B, C and D type portal vein groupwere16.7%,22.2%,22.2%and33.3%respectively. No statistical significance werereached between these groups (P<0.05).According to portal vein form, the patients were divided into normal group (n=79)and variation group (n=21). The variation rate of biliary tract in two groups was30.4%and57.1%respectively. There was statistical significance to make a contrast betweengroups (P <0.05).Conclusion The variations of hilar bile ducts are correlated with that of hilar portalveins. In portal vein variation group, the variation rate of hilar bile ducts elevates, butthe occurrence rate of infraportal type bile ducts does not. The rate of variation insegmental vessels is higher than that of perihilar region, and the segmental vessels’distribution does not obey the Couinaud’s segmentation. Couinaud’s segmentationshould be modified, but it is still valuable in liver surgery.3D technology hasadvantages on the three-dimensional anatomic assessment and can provide importantanatomical information, which should be applied routinely before complex liversurgery.