| BackgroundPrecise anatomic hepatectomy is an important way to treat common benign and malignant liver diseases.Although the vascular alignment of the left liver is relatively fixed compared with that of the right liver,with the development of precise hepatectomy,the identification of the spatial anatomic relationship between the left hepatic vessels and the lesions and the precise hepatectomy based on the hepatic segment or subhepatic segment has become increasingly demanding.In order to ensure the biological behavior of RO resection,reduce intraoperative vascular injury,and reduce postoperative complications,it is necessary to conduct in-depth analysis of the spatial anatomical relationship between the entering and exiting hepatic vessels of the left liver at grade 3-4 before surgery.In previous anatomical studies based on cadaver and liver perfusion cast specimens,due to limited data sources,it is difficult to form a statistical classification of the branch of the left hepatic vein and the branch of the left hepatic portal vein.For example,the number and trend of portal vein branches in segments Ⅰ,Ⅱ,Ⅲ,Ⅳ,the number and trend of left hepatic vein branch,the origin of umbilical rift vein,the number and trend of short portal vessels from the lateral wall of the left and right portal vein main stem and other fine anatomical studies are few,and it is difficult to form the subhepatic segment as anatomical unit classification.As a result,most of the existing surgical methods for left hemihepatopathy are stage Ⅲ,left hemihepatectomy,enlarged left hemihepatectomy and left external lobectomy,etc.Fine surgical resection with hepatic segment or subhepatic segment as the unit of resection is not a conventional surgical method.With the progress of medical 3D visualization soft technology,3D visualization model obtained by a large number of live human preoperative image data can realize the visualization of liver,especially the left half liver and caudate lobe 3-4 branch blood vessels,so that the anatomy of liver segment and sub-liver segment can be more refined,and the fine anatomic resection of liver segment or sub-liver segment with lesions in the left half liver or caudate lobe can also be implemented.Based on the above problems,this project intends to collect the high-quality thin-layer enhanced CT image data of the upper abdomen of normal people,and carry out 3D reconstruction of the vessels of the left portal of liver and caudate lobe through the 3D medical image processing software 3DVWorks(Three-Dimensional Visualization Work System).The branches of portal vein,caudate portal vein and short portal vessels of the left half liver were observed by three-dimensional model.And the three-dimensional anatomy of the branches of the left hepatic vein and the branches of the umbilical fissure vein,etc.,and the statistics and systematic classification were carried out to guide the precise hepatic segment or subhepatic segment resection of the left hepatic and caudate lobe lesions.ObjectivesThe number and spatial trend of grade 3-4 branches of the left hepatic portal vein,the number and spatial trend of the left hepatic vein and its branches,the initial location and spatial distribution of the umbilical frssure vein were studied by three-dimensional reconstruction technology,and 3D classification was performed to guide the precise hepatic segment or subhepatic segment resection of the left hepatic and caudate lobe lesions.MethodsData of 402 patients treated with upper abdominal enhanced CT from November 2019 to January 2023 were collected.According to the specified inclusion and exclusion criteria,data of 244 patients with high image quality were finally included.CT data of portal vein stage and hepatic vein stage in DICOM format were imported into 3DVWorks 3D medical image processing software.The segmentation and reconstruction of each phase image data were carried out.The branch and spatial trend of portal vein,caudate portal vein,portal short vessel,left hepatic vein and umbilical fissal vein were observed and analyzed in the three-dimensional model of left half liver.ResultsThe 3D reconstruction results of 244 selected liver thin-layer enhanced CT images showed that the reconstructed left portal vein and vein structure showed to the 3-4 grade branches,and the number of each subbranch,direction and drainage area were clearly displayed in stereo.The left branch of portal vein:The anatomical results of the left branch of portal vein are as follows:In 242 cases(99.1%),the main line of the left hepatic portal vein was basically fixed,starting from the transverse part of the portal vein and gradually turning to the comer,the left branch of the corner was defined as Ⅱ branch,from the corner to the front into the sagittal part,the right branch of the sagittal part was defined as Ⅳa branch,went forward to the cyst,and the right branch of the cyst was the portal vein branch of the Ⅵb.The left branch of the sac was defined as the Ⅲbranch.In 2 cases(0.9%),the right anterior portal vein originated from the left portal vein trunk.Portal vein branches of segment Ⅱ and segment Ⅲ:Segment Ⅱ sent 1-3 small branches from the corner to the left quadrant of cephalic dorsum,of which 1 branch was sent in 155 cases(63.5%),2 branches in 74 cases(30.3%),3 branches in 15 cases(6.1%).There were 1-4 branches in segmentⅢ,which were divided into the following three categories:Class Ⅰ:Branches distributed in the left quadrant of the cephalic ventral side in 57 cases(23.4%),including 1 branch in 39 cases,2 branches in 14 cases,and 3 branches in 4 cases;Class Ⅱ:129 cases(52.9%)had branches distributed in the left quadrant of the ventral side of the foot,including 37 cases in 1 branch,79 cases in 2 branches,9 cases in 3 branches and 4 cases in 4 branches.In class Ⅲ 58 cases(23.8%)were divided into the above two quadrants.The distance between the starting points of stage Ⅱ and Ⅲ was(1.7±0.7)cm;Taking 2cm as the boundary,the distance between sections Ⅱ and Ⅲ can be divided into the following compact type(the shortest distance between starting points is less than 2cm)and discrete type(the shortest distance between starting points is more than 2cm).Branch of portal vein in segment Ⅳ:15 cases(6.1%)had 1 branch in segment Ⅳ,31 cases(12.7%)had 2 branches,57 cases(23.4%)had 3 branches,69 cases(28.3%)had 4 branches,and 72 cases(29.5%)had 5 or more branches.These branches can be distributed into four quadrants:the right side of the ventral side of the head,the right side of the dorsal side of the head,the right side of the ventral side of the foot,and the right side of the dorsal side of the foot.The starting point of segment Ⅳb is fixed,and 1-7 small branches emanate from the right side of the sac.In segment Ⅳa,1-3 small branches were distributed in different numbers,including the right branch(1.35±0.48),the comer branch(0.74±0.36),and the transverse branch(portal short vessel)(0.39±0.17).According to the above results,the blood vessels in segment Ⅳ were classified by 3D.Type Ⅰ:Cluster distribution of Ⅳb segment+absence of Ⅳa segment,accounting for 8.20%(20/244);Type Ⅱ:More than 2 in section Ⅳb+1-2 in section Ⅳa(lost form),accounting for 65.16%(159/244);Type Ⅲ:More than 2 in section Ⅳb+more than 2 in section Ⅳa(lost form),accounting for 19.67%(48/244);Type Ⅳ:More than 2 branches in section ⅳb+multiple branches in section ⅳA(atraform part+transverse part),accounting for 6.97%(17/244).Short portal vein:The short portal vein refers to the portal vein branches from the ventral and cephalic sides of the main portal vein of the left and right in the transverse sulci of the hilar liver,distributed in segments Ⅴ,Ⅶ and paraval,as well as segments Ⅱ,Ⅳa and Spiegel’s cephalic side(between the transverse and angular parts of the left branch).All of them originated from the transverse groove of the main portal vein,and sent out 3-8 small branches(3.87±1.59)within the range of about 5cm at the bifurcations,and distributed in the paravaval part of caudate lobe and the short portal vessels of Spiegel lobe(3.27±1.59)on average.There were also 51 cases(51/244,20.9%)in which portal short vessels sent off small branches supplying segments Ⅱ(8 cases),Ⅳa(27 cases),Ⅴ(5 cases)and Ⅶ(11 cases).Umbilical fissure vein:In this study,217 cases(88.9%)showed umbilical fissure vein,of which 122 cases were connected to the main hepatic vein(48 cases were within 2cm of the root of the main hepatic vein,74 cases were over 2cm).53 cases were imported into the branch of the root of the left middle hepatic vein(inferior vena cava).42 cases were imported into the main hepatic vein(14 cases were within 2cm of the root of the main hepatic vein,28 cases were over 2cm).According to the above results,the 3D classification of umbilical fissure vein was as follows:Type Ⅰ:the umbilical fissure vein merged into the main hepatic vein,122 cases(56.22%).It was further divided into two subtypes,among which type Ⅰa was imported into the left hepatic vein root within 2 cm,48 cases(22.12%).i.Type b:It was imported into the middle hepatic vein root beyond 2cm,74 cases(34.10%).Type Ⅱ:retrohepatic inferior vena cava,53 cases(24.42%).Type Ⅲ:The umbilical fissure vein merged into the main hepatic vein in 42 cases(19.35%).It was further divided into two subtypes,among which type Ⅲa was imported into the middle hepatic vein root within 2 cm,14 cases(6.45%).Ⅲb type:2 cm outside the root of the middle hepatic vein,28 cases(12.90%).The left hepatic vein and the middle hepatic vein merged into the inferior vena cava in 139 cases(57.0%),and the left hepatic vein and the middle hepatic vein merged into the inferior vena cava alone in 105 cases(43.0%).Conclusions1.The 3D reconstruction and visualization analysis of the left hepatic vessels at the 3-4 levels based on in vivo data is convenient to observe the fine anatomy of the left hepatic lesion at the level of liver segment and liver segment.2.3D classification of blood vessels in the hepatic segment and subhepatic segment of the left liver and caudate lobe can be clinically Ⅳa and Ⅳb resection;Stage Ⅱ and stage Ⅲ resection;Visual guidance is provided for reduced left external lobectomy that preserves the umbilical fissure vein and standard left hemihepatectomy. |
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