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BACKGROUND: The implementation of intraoperative navigation in liver surgery is handicapped by intraoperative organ shift, tissue deformation, the absence of external landmarks, and anatomical differences in the vascular tree. To investigate the impact of surgical manipulation on the liver surface and intrahepatic structures, we conducted a prospective clinical trial. METHODS: Eleven consecutive patients [4 female and 7 male, median age = 67 years (range = 54-80)] with malignant liver disease [colorectal metastasis (n = 9) and hepatocellular cancer (n = 2)] underwent hepatic resection. Pre- and intraoperatively, all patients were studied by CT-based 3D imaging and assessed for the potential value of computer-assisted planning. The degree of liver deformation was demonstrated by comparing pre- and intraoperative imaging. RESULTS: Intraoperative CT imaging was successful in all patients. We found significant deformation of the liver. The deformation of the segmental structures is reflected by the observed variation of the displacements. There is no rigid alignment of the pre- and intraoperative organ positions due to overall deflection of the liver. Locally, a rigid alignment of the anatomical structure can be achieved with less than 0.5 cm discrepancy relative to a segmental unit of the liver. Changes in total liver volume range from -13 to +24%, with an average absolute difference of 7%. CONCLUSIONS: These findings are fundamental for further development and optimization of intraoperative navigation in liver surgery. In particular, these data will play an important role in developing automation of intraoperative continuous registration. This automation compensates for liver shift during surgery and permits real-time 3D visualization of navigation imaging.

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OBJECTIVES: Virtual imaging procedures have only rarely been analyzed in pediatric populations. We evaluated the role of CT-based virtual surgery planning in pediatric patients experiencing hepatic vascular malformations (HVM). METHODS: We analyzed 12 children with complex hepatic vascular malformations. All of the children received multislice CT scans with contrast medium followed by virtual 3-dimensional reconstructions using the software assistants MeVis LiverAnalyzer and MeVis LiverExplorer. The impact on treatment planning and the correspondence to clinical findings was assessed. RESULTS: Highest accuracies of virtual data were found in cases of intrahepatic portocaval shunt and persistent ductus venosus. Here, virtual data revealed congenital vascular conditions, which were not always seen using standard imaging diagnostics. In some patients with portalvenous thrombosis, virtual imaging provided important contributions to determining the feasibility of different shunt procedures. However, in some patients experiencing portalvenous thrombosis or liver diffuse hemangioma, virtual methods were not as accurate as standard diagnostic procedures. Nevertheless, these tools facilitated simultaneous and continuous illustrations of the different vascular systems. CONCLUSIONS: Virtual imaging and planning procedures had an important impact on treatment strategies and outcomes in children with HVM. Their use as standard diagnostic tools in selected cases of HVM should be considered.

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BACKGROUND: Although the consequences of partial venous outflow interruption have attracted only limited attention in liver surgery, maximal preservation of liver function after hepatic resection requires preservation of circulation in the remnant liver, especially hepatic vein drainage. METHODS: Data from 30 patients undergoing 3-dimensional imaging were analyzed to clarify the relationship between the area of the ventral right anterior section (RAS) and that drained by regional hepatic vein tributaries. The feasibility of our preliminary technique of right hemihepatectomy preserving the ventral RAS also was evaluated. RESULTS: The median estimated volume of the ventral RAS was 230 mL (range, 88-391). The average ratio of this estimated volume of the ventral RAS to total estimated liver volume was 18.0 +/- 4.9%. The median volume of the territory served by middle hepatic vein (MHV) tributaries draining the ventral RAS, expressed as a percentage of the whole volume of the ventral RAS, was 82.5%. Findings in fusion images of portal and hepatic vein territories demonstrated an area of MHV tributaries comparable with the ventral RAS area in 73.3% of all cases. As for the results of right hemihepatectomy with the ventral RAS preserved, no tumor was exposed on transection surfaces, and no recurrence took place within the preserved ventral RAS of the remnant liver. CONCLUSION: Procedures considering the importance of regional venous drainage offer the possibility of reducing the extent of surgery without loss of effectiveness.

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BACKGROUND: Complex, highly variable, anatomic relationships in the portal hilum complicate the surgical management at hilar cholangiocarcinoma. Preoperative three-dimensional (3D) imaging to stage the tumor and define anatomy may help in planning for curative resection. METHODS: Between 2003 and 2006, 20 consecutive patients with hilar cholangiocarcinoma underwent preoperative multidetector row computed tomography (MDCT) cholangiography; 3D images of the portal vein, hepatic artery, and bile ducts were created and viewed simultaneously. Longitudinal tumor extension was evaluated by direct cholangiography and 3D cholangiography, and contiguous spread by 2D computed tomography (CT). Of 20 patients, 15 underwent surgical resection. Liver resection was planned based on 3D imaging that allowed visualization of the relationship between the tumor and the umbilical portion of the left portal vein, or the bifurcation of the anterior and posterior branch of the right portal vein. Preoperative and operative findings were compared. RESULTS: All patients tolerated 3D CT without serious complication. The accuracy rates of longitudinal tumor extension, using the Bismuth-Corlette classification system, were 85% (11/13) and 87% (13/15) with direct cholangiography and 3D cholangiography, respectively. The sensitivity, specificity, and accuracy rates were 100%, 80%, and 87% for portal invasion and 75%, 91%, and 87% for hepatic arterial invasion. The number of bile duct orifices in the cut end of the hilar plate was estimated correctly in 13 of 15 patients. There were no operative deaths. Potentially curative resection was achieved in 14 of 15 patients. CONCLUSIONS: 3D images provide accurate information about the relationship between hilar cholangiocarcinoma and adjacent vessels. This technique is a powerful new tool for improving the proportion of potentially curative resection.

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Accurate knowledge of partial anatomy is essential in hepatic surgery but is difficult to acquire. We describe the potential impact of a new technique for constructing three-dimensional virtual images of the portal vein, hepatic artery, and bile ducts and present a representative case. An 80-year-old man was suspected of having papillary cholangiocarcinoma arising in S8 of the liver and extending to the hepatic hilum intraluminaly. Right hemihepatectomy with bile duct resection was planned. However, it was uncertain whether duct-to-duct biliary reconstruction would be possible based on the appearance of the confluence of the right and left hepatic ducts on cholangiogram and conventional computed tomograph. Virtual three-dimensional images of the liver were constructed and revealed vascular and biliary anatomy. They showed that the upper margin of bile duct excision would be 19 mm from the umbilical point of the left portal vein, and that the site of the left branch of the caudate lobe bile duct could be preserved. Based on this information, we performed a sphincter-preserving biliary operation safely without complications. Planning complex biliary surgery may be improved by the use of virtual three-dimensional images of the liver. This approach is especially useful in candidates for postoperative regional chemotherapy.

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HYPOTHESIS: Currently, standard planning for hepatic resection is based on the schematic description of the functional anatomy of the liver according to Couinaud, and on the evaluation of 2-dimensional computed tomographic imaging of the liver. Recent developments in image-based computer assistance allow patients' individual functional liver anatomy to be computed from mathematical analysis of standard multidetector computed tomographic scans. An intended resection can be performed virtually under realistic anatomic conditions, and the influence of different resection planes on blood supply and drainage within the remaining liver parenchyma can be calculated by a computer-assisted risk analysis. We evaluated the impact of computer-assisted risk analysis on operation planning for major hepatectomies, in particular on extent of resection or need for vascular reconstruction. DESIGN: Prospective cohort study. SETTING: Academic tertiary care referral center. PATIENTS: Twenty-five consecutive patients admitted to the hospital for major hepatectomy, of whom 4 had tumors deemed unresectable by both methods. INTERVENTIONS: Two-dimensional computed tomography was used to calculate the volume of the future liver remnant with the intended resection line manually determined, and then the volume of the future liver remnant was calculated again by computer-assisted risk analysis as the remaining liver volume not being devascularized but having both portal venous blood supply and hepatic venous drainage. MAIN OUTCOME MEASURES: The difference between the remaining functional liver volumes calculated by the 2 methods. RESULTS: The deviation between liver volumes determined by 2-dimensional computed tomography and by computer-assisted risk analysis was less than 20% in 14 of 21 patients, between 20% and 30% in 3, between 30% and 40% in 2, and 41% and 43% in 1 patient each. The most extensive deviations were found in extended left hepatectomy or when left hepatectomy was combined with additional wedge resection in the right lobe. In 7 cases, all with a deviation greater than 20%, the results of computer-assisted risk analysis led to a change of operation planning with regard to the extent of resection (n = 3) or the need for vascular reconstruction (n = 4), although in 1 of these cases resection was not performed because of peritoneal carcinomatosis. CONCLUSIONS: Image-based computer assistance allows for areas at risk for devascularization or venous congestion to be identified and precisely calculated before resection. In selected cases with small liver remnants, operation planning may be improved substantially by preoperative computer-assisted risk analysis.

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PURPOSE: Three-dimensional visualization of solid tumors is possible because of high-resolution computed tomography and magnetic resonance imaging scans. However, additional preoperative information is often desirable in complex malignancies. For the first time, the authors present a model of preoperative 3-dimensional visualization and virtual resections in pediatric solid tumors. METHODS: Image analysis of various pediatric tumors was performed using the research software HepaVision2 (MeVis, Bremen). Organs, tumors, and the vascular system were extracted from multislice computed tomography scans. After hierarchical analysis of the vascular system, territories supplied or drained by the major vascular branches were calculated. Results were explored and virtual resections of organs were carried out using the research software InterventionPlanner (MeVis, Bremen). Data were correlated to intraoperative findings. RESULTS: Four hepatic malignancies, 4 renal tumors, and 3 other neoplasms were analyzed. The technique of 3-dimensional visualization was feasible for all investigated children (mean age 5 years and 9 months). Spatial relations between physiological and pathological structures were identified, and anatomical structures (vessels, tumor tissue, and organ parenchyma) were determined using colorimetric encoding. Virtual simulations of tumor resection were used successfully for planning of surgical procedures in the hepatic and renal tumors. CONCLUSIONS: The technique of 3-dimensional tumor visualization and virtual simulation of tumor resections provides the basis for a successful planning of complex tumor resections in children. The efficiency of these techniques should be further analyzed in series with higher numbers and differentiations of tumors.

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RATIONALE AND OBJECTIVES: Quantitative analysis of such small structures as focal lesions in patients with multiple sclerosis (MS) is an important issue in both diagnosis and therapy monitoring. To reach clinical relevance, the reproducibility and accuracy of a proposed method have to be validated. We propose a framework for the generation of realistic digital phantoms of MS lesions of known volumes and their incorporation into a magnetic resonance (MR) data set of a healthy volunteer. MATERIALS AND METHODS: We generated 54 data sets from a multispectral brain scan of a healthy volunteer with incorporated MS lesion phantoms. Lesion phantoms were created using different shapes (three), sizes (six), and orientations (three). An evaluation is carried out from a manual analysis of three human experts and two different semiautomatic approaches, with and without explicit modeling of partial volume effects (PVEs). RESULTS: Intraobserver and interobserver studies were performed for the phantom data sets. All experts overestimated the true lesion volume for any phantom data set (median overestimation between 42.9% and 63.2%). Relative error and variability increased with decreasing lesion size. Similar results were obtained for the semiautomatic approach without PVE modeling. Only the approach with explicit PVE modeling was capable of generating accurate volumetric results with low systematic error. CONCLUSION: The proposed framework based on realistic lesion phantoms incorporated into an MR scan allows for quantitative assessment of the accuracy of manual and automated lesion volumetry. Results clearly show the importance of an improved gold standard in lesion volumetry beyond voxel counting.

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For living donor liver transplantation (LDLT), accurate diagnostic evaluation is essential. Problems arise in assessment of the vascular, bile duct anatomy, liver graft volume, and vascular territories involved. Requirements for the realization of decision-support and enhanced precision in the planning of surgery in LDLT engineering fields are a three-dimensional (3D) visualization system that improves anatomic assessment, allows for interactive surgery planning, and acts as an intraoperative guide. Thirteen LDLT candidates and three LDLT recipients were assessed by "multislice" computer-tomographic examinations. Image processing for 3D visualization included segmentation and calculation of centre lines. A hierarchical mathematical model representing the vascular and biliary tree was created, which allowed calculation of individual vascular territories. Precision of 3D computed tomography (CT)-based visualizations was superior to diagnostic modalities used currently. In addition to detection of decisive anatomic variants, computerized interactive insertion of splitting lines allowed for better planning of the surgical approach and image-guided surgery. 3D CT-based visualization in LDLT facilitates diagnostic evaluation with high accuracy. Multiple examinations, especially with regard to invasive diagnostics, may be avoided. Surgical strategy was directly influenced by the detection of vascular and biliary variants.

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