Three-dimensional CT Anatomy Of Hepatic Veins And Their Spatial Relationship With Intrahepatic Portal Veins

BackgroundThe hepatic veins is the main draining vessel for liver blood,along with the port al veins and hepatic arteries,they maintain the balance of blood flow in and out of t he liver.In recent years,with the increasing incidence of liver cancer and the develop ment of chronic liver diseases,surgeries such as liver resection,living donor liver tran splantation(LDLT),and transjugular intrahepatic portosystemic shunt(TIPSS)have put higher demands on surgeons’ understanding of the complex anatomy of the liver’s inter nal ducts.Multislice spiral CT has various image post-processing techniques,and three-dimensional reconstruction can display the overall structure of the blood vessels,whil e multi-planar reconstruction can display any level simultaneously,which is conducive to observing fine structures.With the increasingly mature application of three-dimensio nal visualization technology in the medical field,it has greatly promoted the research of liver vascular imaging anatomy.However,the current classification methods for the hepatic vein are not unified,and there is still controversy over the clinical features of the right posterior hepatic vein,which will hinder the development of precision medici ne in liver surgery.TIPSS surgery is mostly used for patients with liver cirrhosis,and the liver morphology will change with the progress of liver cirrhosis,and the spatial relationship and distance between the hepatic veins and portal veins may change accor dingly.Understanding these changes can help overcome the challenges faced by TIPSS surgery.In response to the above problems,this study carried out research on the im aging anatomy of the hepatic vein and the spatial relationship between the portal vein s and hepatic veins in patients with liver cirrhosis through multislice spiral CT,in ord er to provide anatomical references for liver surgeons.Part I:Drainage types of three hepatic veins:three-dimensional reconstruction of Dual-Source CTObjective:The 3D reconstruction technique of dual-source CT was applied to study the imaging anatomy of the three main hepatic veins,and a systematic method of hepatic vein typing was proposed,with a view to providing anatomical basis for preoperative planning and intraoperative guidance in hepatic surgery.Methods:We retrospectively analyzed 406 abdominal CT-enhanced scans and performed three-dimensional reconstruction of the images using syngo workstation to observe the way the three hepatic veins drain into the inferior vena cava as well as the number of tributaries of the hepatic veins and the form of drainage,then classify them and to count the percentage of each type.Results:(1)The way three hepatic veins draining into the inferior vena cava can be divided into the following four types:75.1%(305/406)for the trunk type of left and middle HVs,23.2%(94/406)for the non-trunk type of the left,middle and right HVs,1%(4/406)for the trunk type of left,middle and right HVs,and 0.7%(3/406)for the trunk type of right and middle HVs.(2)The left hepatic vein can be divided into three types:type Ⅰ 7.1%(29/406),type Ⅱ 80.6%(327/406),and type Ⅲ 12.3%(50/406).(3)The middle hepatic vein can be divided into four types:type Ⅰ 93.1%(378/406),type Ⅱ 3.5%(14/406),type Ⅲ 1.2%(5/406),and type Ⅳ 2.2%(9/406).(4)The right hepatic vein can be divided into three types:type Ⅰ 44.1%(179/406),typeⅡ 50%(203/406),and type Ⅲ 5.4%(22/406).Conclusion:The anatomical types of hepatic veins are relatively diverse,and 3D reconstructed images can clearly show the way the hepatic veins drain into the inferior vena cava and the course of its tributaries.This study summarizes a more comprehensive anatomical type of hepatic veins based on the previous study,which has important clinical value for hepatic surgery.Part II:Assessment of the prevalence and clinical significance of the accessory right hepatic veins based on dual-source CTObjective:By using spiral CT multiplanar and volumetric reconstruction,the anatomical characteristics of the clinically important accessory right hepatic veins(aRHVs)were examined and analyzed to provide a reference for accurate treatment in hepatic surgery.Methods:This study included 257 images of patients who had undergone enhanced CT scans of the abdomen without liver disease at Shandong Provincial Hospital.The occurrence,number and grouping of this vein were observed on the 3D reconstructed images,and clinically relevant parameters such as its diameter,the diameter of the right hepatic vein,the distance between the right posterior hepatic vein and the right hepatic vein,and the angle between the right posterior hepatic vein and the distal end of the inferior vena cava were measured at different levels of the multiplanar reconstruction.Results:(1)The occurrence rate of aRHVs was 49%(125 cases)and the number was 1 to 3.The occurrence rate of the right posterior middle hepatic vein(MRHV)was 11%(41 cases)and the occurrence rate of the right posterior inferior hepatic vein(IRHV)was 33%(98 cases),and there was no gender difference in the occurrence rate(P=0.063).(2)The mean diameter of aRHVs was 4.91 mm.The diameter of the right hepatic vein was negatively correlated with the diameter of aRHVs(P<0.001),and the greater the number of aRHVs,the smaller the diameter of the right hepatic vein(P=0.048).(3)The distance between the aRHVs and the right hepatic vein at the coronal level was 3.65 cm,with no difference in gender or age(P>0.05).91%(114 cases)of the angles between the aRHVs and the distal end of the inferior vena cava were acute,3%(4 cases)were right angles and 6%(7 cases)were obtuse,with a mean angle of 63.5°,with no difference in gender or age(P>0.05).Conclusion:This study used VR and MPR post-processing techniques to observe and measure clinically relevant parameters such as the emergence rate,diameter and grouping of the right posterior hepatic vein,and to assess for the first time the angle between the aRHVs and the distal end of the inferior vena cava in subjects without liver disease,which will help to increase clinicians’ knowledge of this vein and thus better respond to the need for surgery.Part III:Quantification of the spatial relationship between hepatic veins and intrahepatic portal veins and their alterations in cirrhosisObjective:By establishing a anatomy coordinate system,the in vivo spatial orientation and distance between the branches of the portal vein and hepatic vein were measured,and the changes in orientation and distance were statistically analyzed in patients with liver cirrhosis.Methods:This study included the images of 30 patients with liver cirrhosis who underwent contrast-enhanced CT scans at Shandong Provincial Hospital,as well as the images of 60 healthy subjects without liver cirrhosis.Taking the position of the first hepatic vein that drains the inferior vena cava as the origin,the RAS anatomy coordinate system is established with the coronal axis,sagittal axis,and vertical axis passing through the origin as the X,Y,and Z axes,respectively,with directions from left to right,dorsal to ventral,and inferior to superior.TheΔx,Δy,Δz of the IJK image coordinate system,as well as the image coordinates of the origin of the RAS coordinate system,the endpoint of the right hepatic vein,and the starting point of the right branch of the portal vein,are read in 3D Slicer.A program is developed to achieve automatic conversion from the image coordinate system to the RAS anatomy coordinate system and to automatically calculate the spatial position and distance of the right branch of the portal vein relative to the right hepatic vein.Statistical analysis was performed on the results of the liver cirrhosis group and the control group.Results:(1)The coordinate transformation program can successfully automatically convert the IJK image coordinate system into the RAS anatomical coordinate system,and the spatial position of the portal vein and hepatic vein calculated is consistent with the orientation displayed in the 3D reconstruction.(2)In most people in the cirrhosis group and the control group,the right branch of the portal vein is located on the medial,ventral,and cranial sides of the right hepatic vein,but in 23.3%of the cases(7/30)in the cirrhosis group,the position is medial,dorsal,and cranial,while in 15%of the cases(9/60)in the control group,the position is lateral,ventral,and cranial.(3)The distance between the portal vein and the right hepatic vein in the control group is greater than that in the cirrhosis group,and the difference is statistically significant(P=0.002).Conclusion:This study established a liver-centered anatomical coordinate system and used Python programming language to calculate the pattern of transforming the original coordinate system of the scanned images to this anatomical coordinate system.This achieved a quantitative analysis of the spatial relationship between the hepatic vein and portal vein,and explored the changes in venous relationships in patients with liver cirrhosis,aiming to provide reference for preoperative planning of TIPSS.Conclusion:In this study,CT three-dimensional imaging and multiplanar reconstruction postprocessing techniques were used to conduct extensive research on the anatomy and spatial relationship of hepatic veins.Firstly,this study observed and analyzed the types,tributaries numbers,and course of the three major hepatic veins entering the inferior vena cava,and proposed a new classification method with clinical value based on previous studies.Secondly,this study conducted a detailed quantitative analysis of the relevant parameters of the right posterior hepatic vein from a surgical perspective.Finally,this study established a human anatomy coordinate system and developed a program to measure changes in the spatial location and distance between the portal vein and hepatic vein in liver cirrhosis patients,providing anatomical information for preoperative planning of TIPSS surgery.In summary,this study investigated the imaging anatomy of hepatic veins and their changes in liver cirrhosis patients,which is helpful for clinicians to understand common patterns and provides anatomical evidence for precise treatment of hepatic surgical diseases.