3D Liver Model Research Articles

Surgical anatomy of hepatic caudate lobe based on 3D virtual human liver

Objective To provide practical anatomy of hepatic eaudate lobe for clinical practice. Method Based on Chinese Visible Human 1--5 and assisted by technique of 3D visualization, the dig-itized 3D models of liver were reconstructed and the anatomy of caudate lobe was investigated. Results The right and ventral boundaries of caudate lobe were obscure. The coronal oblique plane through the confluence of hepatic veins and the fissura ligamenti venosi and the sagittal oblique plane through the end of right hepatic vein and the gallbladder fossa could stand for the relative ventral and right borders of the caudate lobe. The caudate lobe could be divided into 2 principal regions: the Spiegel lobe and the paraeaval portion. Conclusion Our classification and the relative borders of the caudate lobe might be reasonable and practical. The 3D visualization is a convenient and accurate study method on clinical a-natomy. Key words: Anatomy; Caudate lobe; 3D visualization; Chinese Visible Human

Virtual piggyback liver transplantation using three-dimensional imaging technique

Objective To study the value of three-dimensional (3D) visualization and virtual surgery system in piggyback liver transplantation. Methods Two patients who suffered from choledocholithiasis were scanned by 64-slice spiral CT and the data were collected. The segmentation of the hepatic CT images was carried out. The 3D model of the liver and the intrahepatic vessels was reconstructed, and was imported to the FreeForm Modeling System in STL format for smoothing and modifying. Piggyback liver transplantation was simulated with the force-feedback equipment (PHANToM). Results The reconstructed 3D model of the liver was vivid, and the process of the virtual piggyback liver transplantation was verisimilar. Conclusions The 3D model of the liver enables the simulation of piggyback liver transplantation. It can reduce the risk and complications of the surgery, and enhance the communication between doctor and patient through designing surgical plan and demonstrating visualized operation before surgery. Virtual liver transplantation is also helpful during the training of medical workers. Key words: Piggyback liver transplantation; Three-dimensional reconstruction; Virtual surgery

The research of virtual hepatectomy

To investigate the methodology of mimic resection system on liver. Hepatic arteries, portal vein, inferior cava vein, hepatic veins and biliary ducts of liver with integrate hepatic portal were perfused with filling materials in different colors. And then the sample was embedded, frozen and slice-cut to obtain serial sectional images. After image registration and segmentation, the 3D reconstruction model which contained the liver's surface and its internal structures was constructed with MIMICS 9.0. Based on the freeform modeling system and its accessories (the software GHOST and the force-feedback equipment PHANTOM), the virtual hepatectomy system was established which could manipulate the virtual scalpel to perform optional resection on virtual liver model. After slice-cutting the cast liver, 910 serial cross-section images were obtained sharply and clearly. The 3D reconstructed liver model looked like the liver sample exactly, and could be magnified, contracted and rotated. In the virtual surgery system with good interaction, powerful immersion and great imagination, the virtual scalpel could be manipulated to perform optional resection on 3D liver model with the haptic device (PHANTOM). The 3D visualized liver and the virtual hepatectomy system has been satisfactorily developed using the hepatic serial sectional images. The process of simulation operation was consistent with clinical practice.

Studies on the hepatic three-dimensional reconstruction and virtual surgery using the hepatic images of the digitized virtual Chinese human female number 1 database

To study digitized virtual hepatic three-dimensional reconstruction and virtual hepatic surgery. The whole series of hepatic images taken from the database of digitized Virtual Chinese Human Female Number 1 (VCH-F1) was employed to reconstruct a three-dimensional (3D) liver. First, studied some algorithms for registration of human liver tissue images, and then, segmented the regions of liver, vein, bile duct, and gallbladder from the images. Based on them, the 3D visualization human liver model was reconstructed. Finally, a 3D visualization demo system of liver was developed based on personal computer and Windows operation system. This demo system of liver provided a graphics user interface to rotate, scale the 3D liver to observe the 3D hepatic structure, and a virtual liver simulation system of resection with primary function. The study may be beneficial to the future research on digitized virtual hepatic and virtual hepatic surgery, and the 3D visualization demo system of liver may be beneficial to the research on the hepatic structure.

The segments of the hepatic veins—is there a spatial correlation to the Couinaud liver segments?

Purpose: To investigate and describe the volume, position and shape of venous segments within the human liver and define their spatial correlation to the Couinaud segments (CS) and to the portal vein segments (PVS). Material and methods: This study was based on 64 routinely acquired CT scans of patients undergoing hepatic surgery. The final analysis included 19 patients. All 19 CT data sets were transformed into 3D liver models. Three venous segments were postulated reflecting the left, middle, and right hepatic vein. Each venous segment was furthermore divided in two venous subsegments. Volume, position and shape of these venous segments/subsegments were calculated and, finally, compared with the volume, position and shape of the Couinaud segments and the portal vein segments. Results: The right hepatic vein covers with 539.8±119.5 ml (47.1%) the largest part of total liver volume followed by the middle hepatic vein 372.7±151.1 ml (32.5%) and the left hepatic vein 248±75.9 ml (20.4%). The Couinaud liver segments and portal vein segments 2, 3, 5, 7, and 8 have consistent positional assignments within the three venous segments. Only the CS 4a, 4b, and 6 showed significantly different positions compared to the PVS 4a, 4b, and 6 ( P<0.03). The venous subsegments have a broad volumetric distribution reaching from 79 to 337 ml. There is no positional correlation of venous subsegments compared to Couinaud segments or portal vein segments at all (kappa<0.75). In contrast, the venous segments/subsegments which can be assigned to either liver halve and either liver lobe have an identical volume, shape and position compared to the corresponding Couinaud liver segments (kappa>0.75). Conclusion: The venous segments distinguish liver areas divided by the left and middle hepatic vein in exactly the same pattern as Couinaud segments and portal vein segments do. However, the comparison of shape and position of venous subsegments showed no correlation with both liver segmental approaches.

Study of liver volume measurement and its clinical application for liver transplantation using multiple-slice spiral CT

Objective To study the accuracy of liver volume measurement using MSCT and its application in liver transplantation.Methods (1) Experimental study.Ten pig livers were scanned using MSCT with two collimations (3.2 mm and 6.5 mm) and pitch 1.25.Semi-automatic method was used to reconstruct 3D liver models to measure the liver volume.(2) Clinical study.Twenty-three patients received MSCT scan with collimation of 6.5 mm before liver transplantation.Same method was used to calculate the liver volume and the measurement was repeated by the same observer after 1 month.Results (1) Experimental study.Actual liver volumes were (1134.1±288.0) ml.Liver volumes by MSCT with two collimations were (1125.0±282.5) ml (3.2 mm) and (1101.6±277.6)ml (6.5 mm).The accuracy was (99.5±0.8)% and (97.4±0.8)%,respectively.Both showed same good agreement with actual liver volume: r=0.999, P0.01.(2) Clinical study.Actual liver volumes were (1455.7±730.0) ml.Liver volume by MSCT was (1462.7±774.1) ml.The accuracy was (99.5±9.6)%,r=0.986,P0.01.Liver volume measured again was (1449.4±768.9) ml,r=0.991 (P0.01).Conclusion MSCT can assess the liver volume correctly,and could be used as a routine step for evaluations before liver transplantation.

パッシブセイフティを実現する手術ロボットナビゲータ

Precise measurements of geometry should accompany robotic equipments in operating rooms if their advantages are further pursued. For deforming organs including a liver, intraoperative geometric measurements play an essential role in computer surgery in addition to pre-operative geometric information from CT, MRI and so on. Previously developed laser-pointing endoscope acquires and visualizes the shape of the area of interest in a flash of time. Using this intraoperative geometry, in this paper we develope a surgical navigator for laparoscopic procedure. This system has the function of intraoperative monitoring and safety management. The authors believe that the proposed function enhances robotically assisted operations not only in ordinary operational environments but also in tele-operative environments. Results of in-vivo experiments on a liver of pig verify the effectiveness of the proposed system. The intraoperative 3D model of liver and 3D geometric calculation in virtual abdominal space were useful to avoid unexpected collisions with the forceps of surgical robot.

Fully Automatic Anatomical, Pathological, and Functional Segmentation from CT Scans for Hepatic Surgery

Objective: To improve the planning of hepatic surgery, we have developed a fully automatic anatomical, pathological, and functional segmentation of the liver derived from a spiral CT scan.Materials and Methods: From a 2 mm-thick enhanced spiral CT scan, the first stage automatically delineates skin, bones, lungs, kidneys, and spleen by combining the use of thresholding, mathematical morphology, and distance maps. Next, a reference 3D model is immersed in the image and automatically deformed to the liver contours. Then an automatic Gaussian fitting on the imaging histogram estimates the intensities of parenchyma, vessels, and lesions. This first result is next improved through an original topological and geometrical analysis, providing an automatic delineation of lesions and veins. Finally, a topological and geometrical analysis based on medical knowledge provides hepatic functional information that is invisible in medical imaging: portal vein labeling and hepatic anatomical segmentation according to the Couinaud classification.Results: Clinical validation performed on more than 30 patients shows that delineation of anatomical structures by this method is often more sensitive and more specific than manual delineation by a radiologist.Conclusion: This study describes the methodology used to create the automatic segmentation of the liver with delineation of important anatomical, pathological, and functional structures from a routine CT scan. Using the methods proposed in this study, we have confirmed the accuracy and utility of the creation of a 3D liver model compared with the conventional reading of the CT scan by a radiologist. This work may allow improved preoperative planning of hepatic surgery by more precisely delineating liver pathology and its relationship to normal hepatic structures. In the future, this data may be integrated with computer-assisted surgery and thus represents a first step towards the development of an augmented-reality surgical system.

Fully automatic anatomical, pathological, and functional segmentation from CT scans for hepatic surgery.

To improve the planning of hepatic surgery, we have developed a fully automatic anatomical, pathological, and functional segmentation of the liver derived from a spiral CT scan. From a 2 mm-thick enhanced spiral CT scan, the first stage automatically delineates skin, bones, lungs, kidneys, and spleen by combining the use of thresholding, mathematical morphology, and distance maps. Next, a reference 3D model is immersed in the image and automatically deformed to the liver contours. Then an automatic Gaussian fitting on the imaging histogram estimates the intensities of parenchyma, vessels, and lesions. This first result is next improved through an original topological and geometrical analysis, providing an automatic delineation of lesions and veins. Finally, a topological and geometrical analysis based on medical knowledge provides hepatic functional information that is invisible in medical imaging: portal vein labeling and hepatic anatomical segmentation according to the Couinaud classification. Clinical validation performed on more than 30 patients shows that delineation of anatomical structures by this method is often more sensitive and more specific than manual delineation by a radiologist. This study describes the methodology used to create the automatic segmentation of the liver with delineation of important anatomical, pathological, and functional structures from a routine CT scan. Using the methods proposed in this study, we have confirmed the accuracy and utility of the creation of a 3D liver model compared with the conventional reading of the CT scan by a radiologist. This work may allow improved preoperative planning of hepatic surgery by more precisely delineating liver pathology and its relationship to normal hepatic structures. In the future, this data may be integrated with computer-assisted surgery and thus represents a first step towards the development of an augmented-reality surgical system.