| BackgroundThe whole prognosis of Primary Hepatocellular Carcinoma have been greatlyimproved since recently twenty years, but at present, therapeutic effect can not reachthe patient hope because of five hundred thousand newly case and ten hundredthousand death case. The partial hepatectomy and liver transplantation, which arebelonged to radical cure, are still the most important choice among the therapy of theliver tumor. The feasibility of the HCC partial hepatectomy should be evaluated inview of the anatomy including of the tumorous size, number, location, the relationwith the vessels inside the tumour, the tumour metastasis, the residue liver functionpost-operation and so on. With the Preoperative adequate evaluation to the patient andthe increasingly knowledge of the anatomy and the liver function and the improvingof the partial hepatectomy skill and postoperative care, the excisional complicationand the death rate had been greatly declined. Now the hepatectomy death ratestandard of the domestic and the abroad is below 3%. At present, with the chiastopicfusion and the rapidly development of the computer skill,the image processing skill,the medicophysics and the medicine, the surgery diagnosis and therapy have great change. In these years, the computer-assisted operation system and the virtual operation system are the achievement of the rapid development of the information science applied in the medical region. The surgeon can make the operation more safe, more reliable and more fidelity by the advanced skill. The flying development in modem science and technology has built a concrete ground for the vital studies on the three-dimensional (3D) reconstruction of hepatic duct systems in recent years. The 3D reconstruction through hispeed CT angiography conducted by Raptopouls V, et al displayed the full views of portal and hepatic veins as well as the spatial conformational relations anatomically so that the portal and hepatic veins can be located and their diameters, obstructions and collateral circulation can be evaluated. Wigmore SJ et al reconstructed liver from the scanned images by helical CT and performed the virtual surgical incision of liver for the purse of assessing the risk of hepatic failure after hepatic incision and deciding the incision range. The three-dimension hepatic and the virtual surgery make use of such imagery sequence as CT and MRI, so as to display a three-dimensional model of the various structures of the hepatic, making the hiding human organ a visible "live" three-dimensional object, Namely visualization. The strengths include: 1) being specifically located in certain space; 2) Being observable in structure and being measurable and available in various data; 3) Enhancing the advancement of anatomical liver. In various surgeries of virtue liver, the CT or MRI examination data of specific liver cancer patients could be employed for image fusion and updating. Hence the surgeons can use their computers to conduct surgical planning, to repetitively test the operational process. Such computerization exercise will help surgeons to optimize the planning, to ensure the surgery quality and safety, and to reduce the operation complications.Recently, with the rapidly development of the science and technology, especially the development of the computer skiU and the modem imageology such as CT,MRI, the computer skill was utilized with the modem medical. The multi-slice helical CT possessed the powerful post-processing function and supplied the detailed image for the clinic with all kinds of the image recombination methods. But the reconstructed image in the 64-slice helical CT workstation actually is plane and two-dimension reconstruction yet, It can not be manipulated as the surgerical organ and be satisfied with the clinic requirement. Therefore, to reconstruct the three-dimension spatial image which can satisfied the clinic requirement including of randomly revolving and dissection and to bring the power feedback feeling when to incision the three-dimension hepatic, these work will bring the far-reaching practical significance for the surgery.ObjectiveTo investigate the behavior of the liver and its interior vessel scanogra based on 64-slice helical CT; to investigate the image segmentation methodology of hand-made and sequence on the scanogra of the liver and its interior vessel based on 64-slice helical CT; to investigation the methodology of the three-dimensional reconstruction by the software MIMICS and the self-designed reconstruction software for the liver and its interior vessel and the virtual liver neoplasm surgical resection mimic system.Methods1. Studies on the three-dimensional reconstruction about the liver image and abdominal cavity artery based on the 64-slice helical CT scanogra(1)Examiner: common health examination person, male, 36 year olds, Body height: 1.76M, Body weight: 74KG(2)Scan condition of the hepatic and hepatic vessel: scan parameter: pip voltage 120KV,tube current 300mAs,every cycle 0.5s,pitch 0.984,slice thickness 5mm(3) Plain scan and Enhanced scanThe Detector 0.625×64, slice thickness 5ram, interval 5ram, Pitch: 0.984, scan sight 40-50cm, matrix 512×512.(4)Enhanced CT scanNon-ionic contrast media with an iodine concentration of 300--- 370 mg/ml are most commonly used and are applied at a flow rate of 5 ml/s depending on the kind of examination. The artery phase delay time after injection: 20-25s.The portal vein phase delay time after injection: 50-55s(5) the liver image collection from the 64-slice helical CT scanogra(6)the three-dimensional reconstruction methods of the liver with intrahepatic vessel: the image was divided by the method of combining liminal value with man-made, then 3D reconstructed the liver model by MIMICS software. The reconstructed target was induced and reserved as the format STL and IGS. When the object were induced into contra- engineering software and were polished, the achieved model can be either to faithful for the initial data or to suit for virtual manipulative finally.2. Studies on the man-made segmentation and three-dimensional reconstruction about the liver image based on the 64-slice helical CT scanogra(1)examiner: the patient suffered left liver tumor, female, 50 year olds, Body height: 1.64M, Body weight: 58KG(2) the liver image collection from the 64-slice helical CT scanogra(3)An unenhanced helical CT of the liver was performed before contrast administration. For biphasic helical CT the liver was scanned in the arterial and the portal-venous phase of liver perfusion. With a power injector, 120ml of Iopromid was injected in an antecubital vein at a flow rate of 4.0ml/s.3.1 CTA scanning: a low-dose preliminary inject test3.2 MSCTP scanning: The portal-vein preliminary test(4)The liver image switching from the 64-slice helical CT scanograThe data were divided into the unenhanced phase, the artery phase, the hepatic vein phase and the portal-vein phase. On the Mxview workstation, all the data were deposited and converted the format DICOM into the format BMP.(5)Liver VisualizationThe different phase image should be treated respectively according to every period image.5.1 Image RegistrationTo adjust every phase image scanning sequence so as to keep the initiation point and the end point equal.5.2 Image SegmentationThe CT image were divided by the software Photoshop 7.0.The methods: the image introduction - liver outline marking - reverse selecting - delete - preserve.5.3 Liver three-dimensional ReconstructionThe series of the liver image which had been divided firstly were imported the MIMICS software. Then the liver image and the duct image were extracted according to their different gray scal. The 3D model of the liver and the intrahepatic vessels were reconstructed by the MIMICS software respectively. The 3D model were outputted into the FreeForm Modeling System in the STL format to make the model smooth and removal the fragment.3. Studies on the sequence segmentation and three-dimensional reconstruction about the fiver image based on the 64-slice helical CT scanogra(1) 64-slice helical CT liver scanograThe same as the collection data set of the second chapter.(2) Liver VisualizationThe different phase image should be treated respectively according to every phase image.2.1 Image RegistrationTo adjust every phase image scanning sequence so as to keep the initiation point and the end point equal.2.2 Image SegmentationFirstly, the liver margin and the vessel were divided from the two-dimensional image in sequence; Secondly, the single organ was 3D reconstructed with the segmentation result. The focal point was to be sure of the image segmentation correct result and to improve the segmentation automatization sequence in the meaning of sequence. In a word, applying for Regions Growth Algorithms realize the sequence segmentation.(3)The three-dimensional reconstruction of the liver with intrahepatic vesselThe MIMICS software and the self-designed software would be applied to reconstruct the three-dimensional liver with intrahepatic vessel model.4. Studies on the virtual surgery about the liver three-dimensional reconstruction based on the 64-slice helical CT scanograVirtual HepatectomyThe 3D liver model with intrahepatic vessel, which had been reconstructed in the second chapter, were Introduced into the FreeForm Modeling System. Based on the FreeForm Modeling System, the software of virtual resection and the virtual scalpel were developed. And then the virtual hepatectomy system was established with the force-feedback equipment (PHANTOM), which can manipulate the virtual scalpel to perform optional resection on virtual liver model. The Virtual Hepatectomy system were established, the different liver resection type were simulated. Results1. Studies on the three-dimensional reconstruction about the liver image and abdominal cavity artery based on the 64-slice helical CT scanograThe 64-slice helical CT scanogra of the liver totally had 676 slice image. The image data were composed of four phase image: the uncontrasted phase; the hetatic artery phase, the portal vein phase, the hepatic vein phase.The reconstructed liver model could reflect the liver real volume and the liver anatomic landmark and demonstrated the liver and the hepatic artery, the portal vein, the hepatic vein and their branch by adjusting the liver clarity simultaneously and respectively.The 3D structure of the inferior vena cava and the hepatic venous clearly demonstrated that the stem and the branch of the Left hepatic veins, the Middle hepatic veins and the Right hepatic veins. The Courser,the caliber of the hepatic veins and the way of the three hepatic veins abouchement into the inferior vena cava could be clearly demonstrated.The abdominal aorta,the arteria coeliaca and its branch suah as: the gastroduoden artery,the renal arteries,the right gastric artery,the left gastric artery,the proper hepatic artery,the splenic artery,the mesentery artery and so on, these artery had the high fidelity and the strong three-dimensional effect. Especially the artery course and caliber was realer and more solid than the anatomy atlas graph.The portal system demonstrated the portal extrahepatic stem and the splenic vein and the sup. mes. vein. The intrahepatic portal system could clearly demonstrate the portal vein stem and the leaf branch, the segment branch of the liver, for example, the transverse part, the anteroposterior axes, the superior lobar branch, the internal lobe branch, the posterior lobe branch, the anterior lobe branch and its next grade branch. The structure of the reconstructed portal vein system was the same as the image of the portal system which was reconstructed in the method of VR on the Mxview workstation of the 64-slice helical CT.2. Studies on the man-made segmentation and three-dimensional reconstruction about the liver image based on the 64-slice hdieal CT scanogra(1) The 64-slice helical CT scanograThe 64-slice helical CT scanogra of the liver totally had 658 slice image. The image data were composed of four phase image: the uncontrasted phase; the hetatic artery phase, the portal vein phase, the hepatic vein phase.The liver outline was clear, the contrast agent in the pipeline of the cross-section was filling well. Every kind of vessel was clarification. The artery phase: the abdominal aorta and the hepatic artery and its branch were clearly demonstrated. The hepatic vein phase: the stem of the hepatic vein was clearly showed, but its branch just can be showed to the third grade vessel. The contrast agent in the inferior vena cava was filling uneven, the portal vein phase: the portal vein system was obviously showed, its branch almost can reach the fifth grade branch. The contrast agent in the portal vein can be showed very well. The demarcation with the liver parenchyma was very apparent.(2)Visualization of liverThe 3D reconstructed liver imageThe 3D liver model by the software MIMICS had the rough surface and the feeling of "stair". The vessels structure was continuity, but the artery surface had many triangular fragment. The 3D reconstructed liver model by the MIMICS software looks like the liver sample when the fragment was removed by the FreeForm Modeling System. The 3D model demonstrated in the FreeForm Modeling System can be magnified, contracted and rotated. The model can be observated in omnibearing. The three kinds of the vessels: the artery, the portal vein and the hepatic vein total introduced into FreeForm Modeling System, the integrity liver with intrahepatic vessels can be finished.3. Studies on the sequence segmentation and three-dimensional reconstruction about the liver image based on the 64-slice helical CT scanogra(1)Liver Image segmentationThe image rapid segmentation in the method of Regions growth could finish dividing the liver scanned image data as soon as quickly. The scanned dataset included 846 slice liver image.(2)The three-dimensional reconstruction of the liver and the intrahepatic vessel and the vessel structural featureThe image dataset which had been Divided in sequence were reconstructed by the software MIMICS. The reconstructed model can showed clearly the hepatic artery, the hepatic vein, the portal vein. The model had stero-image and the appearance fidelity. The portal system can clearly demonstrated the stem of the portal vein formulated from the splenic vein and superior mesenteric vein and the intrahepatic branch of the portal vein.Adopting self-designed software Tony2image, the reconstructed result showed: artery phase hepatic: the appearance fidelity good, the liver anatomic landmark can be clearly observed and the hepatic look like the real hepatic organ. At the hepatic portal, the hepatic artery courser was distorting and fidelity. The hepatic artery location,branch,caliber can observed from the transparent hepatic. After the hepatic in the artery phase and the hepatic in the portal vein phase simultaneously were imported into the software, the two phase hepatic outline almost were overlapping, they had highly goodness of fit. The reconstructed hepatic vein was observed from different direction, the third grade branch of the left hepatic vein, the middle hepatic vein,the right hepatic vein were showed clearly. The reconstructed hepatic in the portal vein phase was translucence, the vessel courser caliber length distribution in the portal vein system were clearly demonstrated.The reconstructed liver model possessed the liver and the hepatic artery, the portal vein, the hepatic vein. The appearance fidelity was better than the real liver. The model can be observed omnibearing just by magnifying, contracting and rotating the model. The model could be demonstrated solo or combination just by adjusting the objective colour and the clarity, the reciprocation analysis could be realized. After the liver visualization, the intrahepatic vessels could be showed in the stero and distinct. The intrahepatic vessels courser, caliber and their relationship could be clearly demonstrated.4. Studies on the virtual surgery about the liver three-dimensional reconstruction based on the 64-slice helical CT scanogra(1) Visualization of liverThe 3D reconstructed liver image.The 3D reconstructed liver model by the MIMICS software looks like the real liver after the fragment were removed by the FreeForm Modeling System. The 3D model demonstrated in the FreeForm Modeling System can be magnified, contracted and rotated. The model can be observed in omnibearing.(2) The virtual partial hepatectomy systemIn the virtual surgery system with interaction and immersion, the virtual scalpel can be manipulated to perform optional resection on 3D liver model with the haptic device (PHANToM). The power feedback can be felt through adjusting the liver intensity.(3)The simulation of the left segment Hepatectomy and Right lobe of liver resection operationIn the virtual surgery system, the virtual scalpel can be manipulated to perform optional resection on 3D liver model with the haptic device (PHANTOM). The left segment Hepatectomy and Right hemihepatectomy were simulated, the effect were the same as the clinic operation. The spatial relationship between the simulated tumour and the intrahepatic vessel can be clearly observed by the action such as turning the liver surface into transparent and rotating and so on. The simulated Hepatectomy was the same as the real surgery. Meanwhile, the power feeling can be touched by the haptic device (PHANToM). A simulation tumor can be manmade with the by GHOST SDK tool and was put into the liver 3D model.Conclusions1. The 3D liver model with intrahepatic vessel, which was 3-dimensionally reconstructed in the combining method of liminal value and man-made using advanced 64-slice helical CT scanogra and MIMICS software, especially the coeliac artery system image is lively, its branch caliber and the relation among the vessels is clearly, may be helpful to operate in the clinic surgery and teaching, hepatic vascular investigation.2. The intrahepatic vessel image can be clearly made by the special angiography on 64-slice helical CT. The 3D liver model with intrahepatic vessel, which was three-dimensionally reconstructed in the method of MIMICS software and of man-made segmentation image from the advanced 64-slice helical CT scanogra, always have smooth and glossy surface, clearly vessel structure, bright-colored, strongly stereo feeling and can become the basis of the virtual operation. The 3D model has good interaction and manifestation and is fit to manipulate.3. In the basis of the second chapter, the segmentation procedural and three-dimensional reconstruction software were self-developed. When the image were divided and reconstructed in the application for the self-device sequence, the result were the same as that using the MIMICS software. Compared with the image using the MIMICS software, the 3D liver model with intrahepatic vessel structure, although the surface was slightly rough, had good stero-effect. Either the liver model imagination or the liver structure and the vessel stereo-position were fully manifested. If the work was continued to be designed, the independence knowledge property right software about the liver image segmentation and the three-dimensional reconstruction will be developed.4. The 3D visualized liver has been satisfactorily developed with the method of surface rendering using the advanced 64-slice helical CT scanogra. Then the developed virtual hepatectomy system and the virtual operation tool based on the haptic devices (PHANToM), which has good interaction, powerful immersion and great imagination, will be of great significance for the promotion of hepatic clinical surgery.
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