Boundaries between subsegments IVa and IVb in the human liver

Until now there has been no definitive anatomical study of the boundary between hepatic subsegments IVa and IVb. In this study, we used a multicolor segmental corrosion cast technique and a multicolor segmental technique on plastinated slices, in combination with helical CT three-dimensional (3D) reconstruction on 15 donated fresh isolated human liver specimens. The corrosion cast technique was carried out on eight of these specimens, and the remaining seven livers were used to make horizontal plastinated slices. Examination of these specimens and observation of 20 additional liver corrosion cast specimens showed that all boundaries between hepatic segments were complex, undulating scissures rather than simple, flat planes. We also found that there was an obvious boundary between subsegments IVa and IVb, such that subsegment IVa laid posterosuperior to subsegment IVb. A tributary of a hepatic vein passed through the boundary between subsegments IVa and IVb, and could serve as an anatomical landmark of this boundary.     

Couinaud肝段在矢状断面上的划分

为给肝内占位性病变的MRI定位诊断提供解剖学依据，利用30例腹部连续矢状断面标本和41例胎肝管道铸型，研究了肝内门静脉和肝静脉的矢状断面表现及Couinaud肝段在矢状断面上的划分，还详细讨论了易致错分肝段的一些因素。     

依据肝静脉断面特点的肝段三维重建

目的构建依据人体肝静脉管道系统断面结构特点的肝段数字化可视模型,为虚拟肝脏手术和数字解剖教学提供形态学依据。方法采用我所建立的数字化可视人体数据集获取的连续肝脏断面图像,通过体数据绘制及面数据绘制的方法,根据肝静脉断面图像的位置和特点,赋予肝段和肝内静脉不同的RGB颜色值进行结构提取,通过计算机三维重建来完成对肝段及肝内主支管道的可视化。结果肝脏数字化可视模型能够清晰显示肝段和肝脏主支管道的形态结构和边界毗邻。结论依据肝静脉断面结构特点的肝段三维重建可视化模型能准确反映出肝段和肝脏主支管道彼此间的形态结构和边界毗邻关系,为肝脏数字解剖教学、虚拟肝脏手术治疗提供理论基础和应用依据。     

Analyzing the human liver vascular architecture by combining vascular corrosion casting and micro‐CT scanning: a feasibility study

Although a full understanding of the hepatic circulation is one of the keys to successfully perform liver surgery and to elucidate liver pathology, relatively little is known about the functional organization of the liver vasculature. Therefore, we materialized and visualized the human hepatic vasculature at different scales, and performed a morphological analysis by combining vascular corrosion casting with novel micro‐computer tomography (CT) and image analysis techniques. A human liver vascular corrosion cast was obtained by simultaneous resin injection in the hepatic artery (HA) and portal vein (PV). A high resolution (110 μm) micro‐CT scan of the total cast allowed gathering detailed macrovascular data. Subsequently, a mesocirculation sample (starting at generation 5; 88 × 68 × 80 mm³) and a microcirculation sample (terminal vessels including sinusoids; 2.0 × 1.5 × 1.7 mm³) were dissected and imaged at a 71‐μm and 2.6‐μm resolution, respectively. Segmentations and 3D reconstructions allowed quantifying the macro‐ and mesoscale branching topology, and geometrical features of HA, PV and hepatic venous trees up to 13 generations (radii ranging from 13.2 mm to 80 μm; lengths from 74.4 mm to 0.74 mm), as well as microvascular characteristics (mean sinusoidal radius of 6.63 μm). Combining corrosion casting and micro‐CT imaging allows quantifying the branching topology and geometrical features of hepatic trees using a multiscale approach from the macro‐ down to the microcirculation. This may lead to novel insights into liver circulation, such as internal blood flow distributions and anatomical consequences of pathologies (e.g. cirrhosis).     

A study of the accessory hepatic vein to segments VI and VII with a morphological reconsideration of the human liver

Introduction The liver is supplied by the common hepatic artery from the celiac trunk and by the portal vein from the gastrointestine. This double blood supply to the liver by the hepatic artery and the portal vein produced a complicated structure in the liver. For the blood outflow, we can see right, intermediate and left hepatic veins, and irregular veins: the accessory hepatic veins. These veins drain the blood in the liver into the inferior vena cava. In this study, we studied the layout of the accessory hepatic vein draining segments 6 and 7 in the human livers and attempted to reconsider the structure of the liver by the layout of the accessory hepatic vein. Methods Sixty livers were subjected in this study. They were prepared by using forceps to trace the layout of the blood vessels inside the livers. We carefully examined the relation between the layouts of the accessory vein to the segments 6 and 7 and of the portal vein. The confluence patterns of the accessory hepatic vein into the inferior vena cava were also examined to find the character of the vein. The relation between the accessory hepatic vein and standard hepatic veins was also studied. Results We found 2.2 accessory hepatic veins in one liver on average in our study. The vein was always within the area of segments 6 and 7, and did not surpass the boundary. We found at most five accessory hepatic veins in a liver in two cases. The accessory hepatic vein to the segments 6 and 7 always had its stem on the dorsal side to the portal vein. Different from the stem, the periphery of the accessory hepatic vein freely distributed with the peripheral branches of the portal vein. The area distributed by the accessory vein was also always dorsal part within the segments 6 and 7. The vein was small usually, but was big in few cases. When the vein was big, the area became solely drained by the accessory vein, because the standard hepatic veins (right and intermediate hepatic veins) did not reach the area, and we did not find any communication between the accessory vein and the standard veins. As the remaining region in the segments 6 and 7 became smaller, the draining right standard hepatic vein became shorter and smaller. Discussion The region drained by the accessory hepatic vein excluded the standard hepatic veins. Therefore, there are two different draining venous networks in the area of segments 6 and 7 classified by Couinaud. Conclusion The accessory hepatic vein draining segments 6 and 7 distributed somewhere dorsal side in the segments 6 and 7. The area where the accessory vein distributed was the region where standard hepatic veins did not reach. This would suggest that the region drained by the accessory hepatic vein makes an isolated segment in the liver in the segments 6 and 7 by the Couinaud’s Classification. The area might have a unique blood circulation system.     

Quantitative analysis of hepatic macro‐ and microvascular alterations during cirrhogenesis in the rat

Cirrhosis represents the end‐stage of any persistent chronically active liver disease. It is characterized by the complete replacement of normal liver tissue by fibrosis, regenerative nodules, and complete fibrotic vascularized septa. The resulting angioarchitectural distortion contributes to an increasing intrahepatic vascular resistance, impeding liver perfusion and leading to portal hypertension. To date, knowledge on the dynamically evolving pathological changes of the hepatic vasculature during cirrhogenesis remains limited. More specifically, detailed anatomical data on the vascular adaptations during disease development is lacking. To address this need, we studied the 3D architecture of the hepatic vasculature during induction of cirrhogenesis in a rat model. Cirrhosis was chemically induced with thioacetamide (TAA). At predefined time points, the hepatic vasculature was fixed and visualized using a combination of vascular corrosion casting and deep tissue microscopy. Three‐dimensional reconstruction and data‐fitting enabled cirrhogenic features to extracted at multiple scales, portraying the impact of cirrhosis on the hepatic vasculature. At the macrolevel, we noticed that regenerative nodules severely compressed pliant venous vessels from 12 weeks of TAA intoxication onwards. Especially hepatic veins were highly affected by this compression, with collapsed vessel segments severely reducing perfusion capabilities. At the microlevel, we discovered zone‐specific sinusoidal degeneration, with sinusoids located near the surface being more affected than those in the middle of a liver lobe. Our data shed light on and quantify the evolving angioarchitecture during cirrhogenesis. These findings may prove helpful for future targeted invasive interventions.     

Surgical anatomy of hepatic venous system

Surgeons are comfortable with nearly all the intraabdominal structures except the liver. The reason for this is an unfamiliarity with the large intrahepatic venous structures. This arises because current educational methods, illustrations, and prepared casts are relatively unhelpful. The intrahepatic anatomy is best studied by specially prepared dissections that show the vascular structures, with their interrelationships, and the routes of access to these vessels. Forty formalin-hardened livers were thus dissected. The fissures and portal and hepatic veins have been displayed to emphasize their relations to each other with a view to facilitating their exposure at surgery.     

国人肝段的再认识

目的:对肝内门静脉和肝静脉重新认识,提出一种新的国人肝段划分方法,为影像学和肝外科提供断层解剖学资料。方法:使用50例上腹部连续断层标本和20例多层螺旋CT图像及三维重建图像,研究了肝内门静脉的走行和分布以及肝静脉及其属支的回流范围及其两者之间的相互关系。结果:国人肝段新的划分方法:门静脉右支主干存在时,依肝中静脉所在的正中裂将肝分为左、右半肝。右半肝被一弯曲的右叶间裂分成右前上叶和右后下叶。右前上叶依垂直段间裂分为腹侧和背侧段。右前上叶的腹侧段被水平亚段间裂分为上、下两个亚段。右后下叶依水平段间裂分为上、下两段。肝左静脉主干存在时,依肝左静脉主干所在的左叶间裂将左半肝分成左后上叶和左前下叶。左前下叶依左段间裂分为内侧和外侧段。水平亚段间裂将左前下叶的内侧段分为上、下两个亚段。依弧形背裂分尾状叶和右前上叶及左前下叶内侧段。结论:国人肝段新的划分法不仅有利于肝内微小病变的精确定位,而且便于肝外科探索新的和更加安全的术式来施行各种肝切除和肝移植。     

Diaphragmatic sulci and portal fissures

Diaphragmatic sulci in the superior surface of the liver were found in 40% of cases at autopsy. All sulci were located in the right lobe and in 47% they were multiple. In order to evaluate possible predisposing factors for these accessory sulci, their topography and characteristics were observed in unfixed livers; moreover, intravenous injections of radio‐opaque resins were performed in the portal and hepatic veins (HVs). After formalin fixation, the livers underwent CT and MR scans and a three‐dimensional (3D) elaboration of the images was performed. Radiological examination revealed a correspondence between the topography of the sulci and the course of the right and middle HVs and their main tributaries in 67%. The corrosion casts showed the location of the sulci at the level of the boundaries between the ramifications of the terminal branches of the portal triad, where the HVs are located, in 73%. These findings suggest that, rather than the action of ‘special’ or hypertrophied muscle bundles, the pressure exerted by the diaphragm as a whole may be responsible for the production of sulci at the level of weak zones, represented by the portal fissures, where the watershed superficial hepatic parenchyma, owing to the absence of all but the smallest vascular branches, exhibits a lower resistance to external pressure.     

Reconfirmation of the right medial division of the portal venous system of liver

With the development of hepatic surgery and radiology, an increasing amount of researchers have reported discrepancies between the real distribution of the hepatic portal vein branches and Couinaud's segmentation, especially for further division of the right medial division. The present study investigated 25 cadaveric liver dissections and 30 three-dimensional reconstruction images of intrahepatic vessels. The ramifications, course, distribution and quantity of the portal branches were analyzed. An oblique fissure that had few vessels was found among third-order branches of the hepatic portal vein of the right medial division. The right medial division could be redivided into the ventral subsegment and dorsal subsegment by this oblique fissure. A hepatic vein coursed in the oblique fissure between the ventral subsegment and dorsal subsegment. The hepatic vein could serve as an anatomical landmark of the inter-subsegmental plane. This new method of identifying further division of the right medial division is a novel concept providing further information on conventional segmental anatomy.     

基于冠状面数据的肝静脉和肝内门静脉的三维重建

目的:构建基于肝连续薄层冠状断面数据集的肝静脉和肝内门静脉的三维数字化可视模型。方法:应用数控冷冻铣削技术获取1例肝的连续薄层冠状断面数据集;采用体绘制和面绘制的方法,通过人工干预对数据集中肝内管道系统进行人工识别提取和图像数据分割;运用3D医学可视化软件实现三维重建,构建肝静脉和肝内门静脉的三维可视化模型。结果:肝静脉和肝内门静脉的可视化模型可清晰显示门静脉及其分支和肝静脉及其属支的空间构形,真实地再现了肝门静脉和肝静脉之间复杂的空间毗邻关系。模型中的肝静脉和肝门静脉可单独或总体显示,可在三维空间位置上绕任意轴旋转任意角度,并能从不同的角度对某一血管分支进行多角度、多方位的观察。结论:高质量的二维图像、精确的数据分割和合适的三维重建方法保证了三维数字化可视模型的真实性和准确性。     

左外叶活体肝移植的解剖学研究

目的：模拟左外叶活体肝移植门静脉、肝动脉和胆管的切取方法。方法：解剖正常人肝脏标本30具，观察肝脏铸型标本30具，测量门静脉、肝动脉及胆管长度、管径及属支或分支分布情况。结果：左外叶门静脉的血供来自门静脉左支，主要为左外叶上段门静脉支、左外叶下段门静脉支；动脉主要来源于肝固有动脉、肝左动脉、肝中动脉，偶有迷走动脉支；胆道引流属支有左外叶上段胆管支、左外叶下段胆管支。结论：左外叶解剖变异较多，活体取肝前应仔细研究其结构特点，设计合理的切取模式；对门静脉、肝动脉和胆管支需行必要的整形，以便与受体相应的管道进行吻合。     

Phylogenetic analyses of the hepatic architecture in vertebrates

The mammalian liver has a structural and functional unit called the liver lobule, in the periphery of which the portal triad consisting of the portal vein, bile duct and hepatic artery is developed. This type of hepatic architecture is detectable in many other vertebrates, including amphibians and birds, whereas intrahepatic bile ducts run independently of portal vein distribution in actinopterygians such as the salmon and tilapia. It remains to be clarified how the hepatic architectures are phylogenetically developed among vertebrates. The present study morphologically and immunohistochemically analyzed the hepatic structures of various vertebrates, including as many classes and subclasses as possible, with reference to intrahepatic bile duct distribution. The livers of vertebrates belonging to the Agnatha, Chondrichthyes, Amphibia, Aves, Mammalia, and Actinopterygii before Elopomorpha, had the portal triad‐type architecture. The Anguilliformes livers developed both periportal bile ducts and non‐periportal bile ducts. The Otocephala and Euteleostei livers had independent configuration of bile ducts and portal veins. Pancreatic tissues penetrated the liver parenchyma along portal veins in the Euteleostei. The liver of the lungfish, which shares the same origin with amphibians, did not have the portal triad‐type architecture. Teleostei and lungfish livers had ductular development in the liver parenchyma similar to oval cell proliferation in injured mammalian livers. Euteleostei livers had penetration of significant numbers of independent portal veins from their intestines, suggesting that each liver lobe might receive a different blood supply. The hepatic architectures of the portal triad‐type changed to non‐portal triad‐type architecture along the evolution of the Actinopterygii. The hepatic architecture of the lungfish resembles that of the Actinopterygii after Elopomorpha in intrahepatic biliary configuration, which may be an example of convergent evolution.     

Portal Venous Territories Within the Human Liver: An Anatomical Reappraisal

Subdivision of the human liver into eight portal venous segments (according to Couinaud) is largely established in the anatomical and clinical community. However, this concept is challenged by an increasing number of surgical and radiological reports. We reexamined the intrahepatic portal venous architecture to understand the inconsistencies published. For this purpose, we studied the livers of 20 deceased who had donated their body to the Anatomy Department. The organs were investigated by portal venous injection, subsequent liver corrosion, and analysis of the branching pattern. After a usual bifurcation of the portal vein (order 0 vessel) into a right and left branch (first order vessels), the number of second order branches observed was between 9 and 44, with an average of 20. This seemingly trivial matter of fact suggests that the human liver does not consist of the eight segments presumed, but of many more. Supposedly contradictory observations turn out to be explainable by differing combinations of this large number of territories, and not simply by anatomical variability. For practical surgical purposes, we conclude that the useful eight‐segment scheme needs conceptual reappraisal when a more realistic approach to the individual hepatic territoriality in the patients under consideration is demanded. We submit a “1‐2‐20‐concept” as a possible key. Anat Rec, 291:636–642, 2008. © 2008 Wiley‐Liss, Inc.     

蛋白酶腐蚀法在保留肌腱的血管铸型中的应用研究

目的　使用蛋白酶消化技术制作保留肌腱的血管铸型,拓展解剖学标本类型,丰富肌腱相关的临床解剖学研究方法。 方法　分别使用浓度为0.5%、1.0%、1.5%和2.0%的蛋白酶混合液对掌长肌进行分解实验,选出适合分解肌组织的基础浓度;以丙烯酸树脂为填充剂,灌注新鲜前臂标本的血管,制作铸型标本。填充剂凝固后,将前臂标本浸泡于起始浓度为1.0%的蛋白酶溶液,每24 h在混合液里加入35 g碱性蛋白酶粉,腐蚀5 d后获得保留肌腱的前臂血管铸型标本。 结果　通过对掌长肌组织进行分解实验发现,浓度为1.0%的蛋白酶混合液在肌腱断裂前能更充分地分解肌腹组织;通过对保留肌腱的血管铸型观察发现,其皮肤、脂肪组织和肌组织的肌腹基本消失,而骨骼、肌腱和铸型血管基本保存完好,可以清晰地观察皮肤及浅层、肌腱和肌腹丰富的血供来源、走向及其分布,清晰地观察铸型血管与皮肤及浅层、肌腱和肌腹的立体关系。 结论　以1.0%为起始浓度,每24 h加入1次起始浓度所需溶质（碱性蛋白酶）剂量的50%所配制的蛋白酶混合液,是制作保留肌腱的血管铸型的合适腐蚀液;保留肌腱的血管铸型为新的解剖学标本类型,并丰富了肌腱相关的临床解剖学研究方法。     

蛋白酶腐蚀法在保留肌腱的血管铸型中的应用研究

目的　使用蛋白酶消化技术制作保留肌腱的血管铸型,拓展解剖学标本类型,丰富肌腱相关的临床解剖学研究方法。 方法　分别使用浓度为0.5%、1.0%、1.5%和2.0%的蛋白酶混合液对掌长肌进行分解实验,选出适合分解肌组织的基础浓度;以丙烯酸树脂为填充剂,灌注新鲜前臂标本的血管,制作铸型标本。填充剂凝固后,将前臂标本浸泡于起始浓度为1.0%的蛋白酶溶液,每24 h在混合液里加入35 g碱性蛋白酶粉,腐蚀5 d后获得保留肌腱的前臂血管铸型标本。 结果　通过对掌长肌组织进行分解实验发现,浓度为1.0%的蛋白酶混合液在肌腱断裂前能更充分地分解肌腹组织;通过对保留肌腱的血管铸型观察发现,其皮肤、脂肪组织和肌组织的肌腹基本消失,而骨骼、肌腱和铸型血管基本保存完好,可以清晰地观察皮肤及浅层、肌腱和肌腹丰富的血供来源、走向及其分布,清晰地观察铸型血管与皮肤及浅层、肌腱和肌腹的立体关系。 结论　以1.0%为起始浓度,每24 h加入1次起始浓度所需溶质（碱性蛋白酶）剂量的50%所配制的蛋白酶混合液,是制作保留肌腱的血管铸型的合适腐蚀液;保留肌腱的血管铸型为新的解剖学标本类型,并丰富了肌腱相关的临床解剖学研究方法。     

A multilevel framework to reconstruct anatomical 3D models of the hepatic vasculature in rat livers

The intricate (micro)vascular architecture of the liver has not yet been fully unravelled. Although current models are often idealized simplifications of the complex anatomical reality, correct morphological information is instrumental for scientific and clinical purposes. Previously, both vascular corrosion casting (VCC) and immunohistochemistry (IHC) have been separately used to study the hepatic vasculature. Nevertheless, these techniques still face a number of challenges such as dual casting in VCC and limited imaging depths for IHC. We have optimized both techniques and combined their complementary strengths to develop a framework for multilevel reconstruction of the hepatic circulation in the rat. The VCC and micro‐CT scanning protocol was improved by enabling dual casting, optimizing the contrast agent concentration, and adjusting the viscosity of the resin (PU4ii). IHC was improved with an optimized clearing technique (CUBIC) that extended the imaging depth for confocal microscopy more than five‐fold. Using in‐house developed software (DeLiver), the vascular network – in both VCC and IHC datasets – was automatically segmented and/or morphologically analysed. Our methodological framework allows 3D reconstruction and quantification of the hepatic circulation, ranging from the major blood vessels down to the intertwined and interconnected sinusoids. We believe that the presented framework will have value beyond studies of the liver, and will facilitate a better understanding of various parenchymal organs in general, in physiological and pathological circumstances.     

Hepatic microcirculation as a morpho-functional basis for the metabolic zonation in normal and pathological rat liver

The hepatic microcirculation is well known as a fundamental component of the liver structure, deeply involved in the zonal organization of the acinar structure. In cirrhosis, the microvascular tree shows dramatic changes that would heavily influence the development of the disease. When the cirrhosis becomes evident the result is a progressive organ failure, also in presence of only moderately decreased hepatocyte volume. The aim of this research was to compare the role of microcirculation of the hepatic zonation in normal and cirrhotic livers. Cirrhosis was experimentally induced in 36 rats following a controlled intragastric CCl4 administration. Cirrhotic and control normal livers were processed for routine light microscopy, histoenzimology, and scanning electron microscopy vascular corrosion cast. Control livers showed normal hepatic structure and microvascularization; enzymatic activities were constantly and normally distributed. In CCl4-treated animals LM showed a characteristic micronodular cirrhosis in all livers. Vascular corrosion casts under the scanning electron microscope displayed a progressive reduction of the distance between pre- and post-sinusoidal vessels and the presence of newly formed perinodular plexus. The histoenzymatic analysis demonstrated the loss of zonation in the cirrhotic parenchyma. Moreover, the sinusoid/hepatocyte ratio was significantly reduced, because of the presence of two or more hepatocyte thick laminae during the scarring development. The altered microcirculation in cirrhosis also changed the normal acinous metabolic gradient. The histoenzymatic study revealed a zonal rearrangement of the cirrhotic liver metabolic activity, that leads to a progressive hepatic failure. These data confirm the fundamental importance of the normal relationship between the hepatocyte laminae and the sinusoids for the preservation of a normal zonation which represents the basis for a normal liver function.     

左肝管全程剖开胆肠吻合术的应用解剖学研究

左肝管全程剖开手术,必须熟悉左肝管与邻近血管的局部解剖关系.为此我们用 ABS 丙酮溶液灌注塑型了6具新鲜成人尸肝脏,解剖40例(成人30,儿童10)肝脏标本,测量了左肝管长度和管径,左肝管与肝总管夹角。全程剖开左肝管与右肝管,并观察左肝管与右肝管、左肝动脉、门静脉左干和肝圆韧带的关系,提出了右肝管全程剖开手术方法和注意事项。     

Intrahepatic Branching Pattern of Portal Vein

The variations in the branching pattern of Portal vein within liver are mandatory factor while dealing with Subsegmental Hepatectomy. The variations in the Intra hepatic portal vein branching need to be recognized when contemplating an initial ligation of the vessels at the porta hepatis during partial hepatectomy. This study, was done in 47 adult human liver specimens and 3 fetal liver specimens. In this study different methods like manual dissection, corrosion cast and Radiological study methods used. During this study the “BIFURCATION” or “TRIFURCATION” pattern of portal vein, accessory branches from its branches and relation between, portal vein and hepatic vein were observed. The knowledge of the portal vein and its intra hepatic branching, including their variations are crucial to ensure surgical success pertaining to different and modern surgical procedures.