The CT3D Reconstructions Of Short Hepatic Veins And Its Application In The Hepatectomy

BackgroundShort hepatic veins (SHVs) are regarded as the accessary hepatic venous drainage, and it attracts more and more surgeons’ attention. Previous study had shown that the size of the SHVs is smaller than the three main hepatic veins, and their mainly function is to drain the caudate lobe, including the caudate lobe of Spiegel lobe, paracaval portion, and caudate process. While existing of the undeveloped right hepatic vein, there will be the inferior right hepatic veins. Moreover, the large size of this kind vein can bring significant clinical value. Depending on the SHVs’ distribution, some SHVs will drain the segment8.Concerning the draining part of the certain SHVs, it will assist surgeons to perform well in hepatectomy. Previous studies showed that when the remaining part of the liver after hepatectomy, it will cause serious morbidity, as delayed bleeding, liver failure and bile leak, etc. If the main hepatic veins were damaged, the SHVs can act as an alternative supplement for hepatic venous drainage, and it will prevent the occurrence of the postoperative complication.SHVs’ size, distribution and amount vary significantly in humans. When existing of the large inferior right hepatic veins (IRHV), it’s eligibility to resect the superior segment of the right liver without reconstructing the right hepatic veins. Because the IRHV assist to drain the remaining segment6. It is essential to ligate the SHVs while resecting the caudate lobe, especially for the diameter of the SHVs larger than3mm. The spillage of the inferior vena cava (IVC) can lead to massive bleeding, and can be worsened by clamping blindly. The distributions of the SHVs on the IVC varied significantly, previous studies showed there existed an avascular line of1cm on the retrohepatic IVC (RHIVC). Based on this anatomical characteristic, surgeons can place a hanging tape to assist the hepatectomy.In recent years, surgeons continued to modify the liver hanging maneuver (LHM) to increase the safety of this procedure. Previous studies reported three kinds of approaches to build the retrohepatic tunnel, which are the classic approach on the10-11o’clock raised by Belghiti, right lateral approach raised by Chen, left approach after dissecting behind the common trunk of middle hepatic veins and left hepatic veins, respectively. Meanwhile, anatomists also further the studies on the anatomical bases for this kind of avascular zone on the10-11o’clock on the RHIVC. Most studies had confirmed this avascular zone is indeed an relatively low density of the SHVs. Chen’s approach and Kim’s approach are both appropriate for building the retrohepatic tunnel. Based on the preoperative assessment of the SHVs, surgeons can choose the most appropriate approach for the LHM, and it guide the safe performing of this maneuver.In this study, the individual variations of SHVs were anatomically investigated using Medical Image3D Visualization System (MI-3DVS) by way of analyzing and treating epigastrical CT imaging data of2175volunteers. In return, the acquired results in the individual variations were applied in the simulated surgical system for diagnosis of hepatic cancer as well as operation planning. The model of individual variations has its values clinically for diagnosis improvement of hepatic carcinomas, direction for actual manipulations of hepatic surgery, conservations of more normal hepatic tissues and reduction of postoperative complications. The CT3D reconstructions of short hepatic veins and its application in the hepatectomyPurpose1. To study the characteristics of individual digitized short hepatic vein imaging by MI-3DVS reconstruction;2. To investigate the size and distribution on the RHIVC of digital short hepatic;3. To explore the value of the individual digital short hepatic vein in liver surgery.Methods1. Patients and CT scanningThis retrospective study was performed on175consecutive patients (95men,80women; age range25-53, mean43years) with hepatobiliary disease between March2012and October2013in the Department of Hepatobiliary Surgery (I), Zhujiang Hospital Southern Medical University. The ethics committee of the Southern Medical University approved this study.. Exclusion criteria included the following:(1) patients who had received the liver resections;(2) patients whose hepatic tumors invading or abutting the RHIVC;(3) patients whose CT imaging effect of the SHVs score0and1(Table1).2. CT scanningThe data were collected using a Philips Brilliance64-MDCT scanner. Enhanced CT scanning was performed as follows:dynamic abdominal triphasic tomography and thin slice scanning were performed for the patients after non-ionic Iopamiro, an intravenous contrast agent, was administered. Each patient received80-100mL of the vascular contrast agent. The contrast was injected at a rate of5mL/s, followed by vascular flushing with40-50mL of normal saline at the same rate. Arterial-phase scanning was achieved by contrast agent tracing; specifically, the scanning was automatically triggered8s after the vascular CT value in the diaphragmatic section of the abdominal aorta reached100HU. Portal venous phase scanning was initiated by the same criterion but with a60s delay; the scanning covered the area from the diaphragm to the lower poles of the kidneys. The scanning parameters included a voltage of120kV, a current of200mA, a slice thickness of5mm, an interval of5mm, a detector combination of0.625mm×64, a pitch of0.894, a bed speed of47.5mm/s, and a rotation time of0.5s.3. Image analysis and CT3D reconstructionTwo radiologists and one liver surgeon to identify the SHVs in the CT images, then they measured the diameters of the SHVs and got the mean diameters of those SHVs. The SHVs were classified as small, medium, and large when <3,≥3to<6, and>6mm in diameter, respectively. After all these measurement, the CT images were transferred to a dedicated workstation (MI-3DVS workstation). CT images were analyzed with the software called the medical image3D visualization system (MI-3DVS) originally developed by us to create the3D models of the SHVs, the RHIVC, the portal vein and the liver21. Then these3D models were imported into the free-form modelling system to perform the virtual liver hanging maneuver.4. Typical cases of clinical applicationsPreliminary evaluation of the application value of short hepatic vein reconstruction, select the actual clinical three cases illustrate typical cases are introduced. Example1is a mid-HCC liver, Example2is an example of the left liver cancer, liver cancer case of Example3is the caudate lobe. Three-dimensional reconstruction were preoperative liver segmentation and volume calculations and simulation preoperative planning, after the actual surgery, before the mid-liver resection were performed pathway, the former pathway left hepatectomy and caudate lobe joint right liver resection.4.1three-dimensional reconstructionMI-3DVS reconstruction completed by the researcher, is: a "revascularization" module of the hepatic vein, portal vein, hepatic vein and inferior vena cava and hepatic short segmentation, reconstruction, segmentation of " domain segmentation method" Lord, some small vessels using the "semi-interactive segmentation method "; adopt "organ reconstruction" module on the liver segmentation, reconstruction, segmentation using the " region growing." 4.2liver segmentation and volume calculationsThe three-dimensional model reconstructed into Freeform Modeling Plus, follow the hepatic vein and portal vein based on the principle of Couinaud, a "three-dimensional box method" liver segments. As a result, each segment has its own liver blood supply and return system, can be regarded as a functional unit of the liver, liver segment divided each good in different colors to contrast with distinction. After a three-dimensional model of the three-dimensional reconstruction of the MI-3DVS the volume measurement modules, measure out the whole liver volume and tumor volume, according to the results of hepatic liver segmentation locate tumors located in the calculated volume of the tumor-bearing liver resection and residual liver volume.4.3surgical planning4.3.1Simulation liver resectionFor patients before liver surgery placeholder routine surgical simulation exercises. The use of surgical instruments simulation system (software works No.:2008SR18799) self-development, the establishment of a virtual surgical environment in the computer, according to the different characteristics of the patient and in accordance with the needs of a liver surgical cutting simulation to assess liver resection assisted surgery before after the function of liver volume percentage of the original volume of the whole liver, which is conducive to the prevention of postoperative liver function due to lack of volume as a result of liver failure and other complications.4.3.2Tunnel is established and placed around the liver For the implementation of the scheme around the liver in patients with liver resection Czochralski method before pathways after hepatic inferior vena cava wall looking for "a relatively avascular zone", an analog implementation, after the establishment of the liver tunnel.4.4The actual surgery4.4.1pathway in front hepatectomy:(1) the establishment of liver tunnel, around the liver into the double dip with:①the latter revealed hepatic vena cava, the caudate lobe lift caudate process along the inferior vena cava isolated up front, short hepatic veins may be encountered transection ligation;②liver tunnel is established in accordance with classical approach introduced:revealing the right hepatic vein, hepatic vein and left hepatic vein between the veins of dry, asking after the tracks, loose tissue can blunt the downward separation within the notch;③10to11o’clock position hepatic inferior vena cava wall extending into large curved forceps carefully separated from the cephalic direction hepatic venous lacunae forward, gently rotate the face of resistance, do not use violence, when viewed from the hepatic venous lacunae piercing, which means that the tunnel is successfully established;④After the tunnel is successfully established liver, liver traction around with two from bottom to top through this tunnel.(2) transection of the liver parenchyma:Preset first portal hepatic inferior vena cava with; assistant pulling around the liver with delineate pre tangent, split liver parenchyma scrape suction method, in case the piping system are to be ligated, to be completely split, you can fully exposed to the liver after anterior inferior vena cava, left hepatic pedicle, the right hepatic vein, the left hepatic vein and the hepatic vein were dry, ligation of the hepatic vein and hepatic vein is short, then the free hepatic ligament to remove the tumor.4.4.2The former pathway left hepatectomy:(1) the establishment of liver tunnel, into pulling the belt around the liver:with6.1.(2) transection of the liver parenchyma:Anatomy first portal, the left hepatic duct, left hepatic artery and left portal vein were isolated, and vessel occlusion band ligation, pre-blocked with hepatic inferior vena cava, then liver visible on the surface of ischemic zone, the extension of ischemia with suction method to scrape split liver parenchyma, in case pipes are to be neutered, until the second hepatic hilum, ligation of the left hepatic vein, hepatic ligament free to remove the tumor.4.4.3Joint right caudate lobe hepatectomy:①free sickle hepatic hilum ligament to the second separation on the right coronary ligament, triangular ligament, liver and right superior vena cava ligament, exposed to the liver bare area, this when the right hepatic ligament is completely free;②anatomy second portal isolated extrahepatic right hepatic vein in juxtaposition with blocking, pre-hepatic inferior vena cava with;③anatomy first portal separate ligation on the right Glisson beam, with the right hepatic ischemia occurs, the pre-designated tangent;④turn to the left to the right lobe separation gap between the tumor and the inferior vena cava, the right to left ligation, cut short hepatic veins;⑤extension of pre-tangent suction method to scrape split liver parenchyma in the liver to the second portal right hepatic vein ligation right Glisson beam cluster ligation.5. Statistical analysisMultiple comparison among several sample rates was determined with the Pearson chi-square test. And if there was a statistically significant different among all the groups, pairwise comparisons were performed by the Partition of Chi-square method. Kruskal-Wallis H test was used to compare the composition of the groups with non-normally distributed variables. If the cells’ count less than5exceeds1/5of the total number, we shall combine the adjacent group. P≤0.05was considered statistically significant, and the program SPSS, version13.0software package was used for statistical analysis.Results1.1short hepatic veins display of three-dimensional reconstructionReconstruction using MI-3DVS stereoscopic three-dimensional model, realistic shape, contrasting observer in MI-3DVS or FreeForm Modeling System for three-dimensional reconstruction of the model can be arbitrary zoom, rotation, perspective and so treatment can also be select the transparency and color control target (Figure2), set the display alone or in combination, can clearly understand the anatomy of internal abdominal organs and blood vessels.1.2short hepatic veins in the liver distribution under the vena cava wallIn selected175patients, showed good short hepatic vein reconstruction, reconstruction of the display rate of100%. Based on cross-sectional CT-clockwise direction, the short hepatic veins in the liver under the distribution division of the superior vena cava wall6-9’,9-12’ and12-3’ of three regions, including9-12’basis clockwise direction continue into9-10’,10-11’ and11-12’ clock direction According to the regional statistics,6-9’ bell short hepatic veins occur85.7%(150/ 175),9-10’short hepatic veins appear bell was22.9%(40/175),10-11’ bell appeared short hepatic veins was14.9%(26/175),11-12’appears bell short hepatic veins was32.0%(56/175),12-3’ short hepatic veins appear clock rate of54.3%(95/175).3constitutes a characteristic short hepatic vein diameter sizeAccording to the diameter of the short hepatic veins D<3,≥3D<6, and D≥6mm divided into small, medium and large hepatic vein diameter short description, the diameter of the different regions appear to constitute a short hepatic veins6-9’ bell short hepatic veins configured (81/107/41),9-10’ bell short hepatic veins composed of (33/10/0),10-11’ bell short hepatic veins composed of (22/7/0),11-12’ bell short hepatic veins composed of (46/12/1),12-3’ bell short hepatic veins composed of (53/50/1).Conclusion1After the64-slice spiral CT hepatic vein enhanced scan data sets, using MI-3DVS digitized three-dimensional reconstruction based on short hepatic vein model clear, realistic, three-dimensional sense, the distribution can be obtained short hepatic veins, the size, the number of individuals of information; liver in individual segments, surgical risk assessment, the choice of surgical approach has great value.2Large IRHV and10-11’clock direction appears short hepatic veins in the liver surgery should attach great importance to the role of full use of these variants, digital three-dimensional reconstruction of individual models can provide important information.