Role of new three-dimensional image analysis techniques in planning of live donor liver transplantation, liver resection, and intervention.
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Computer Simulation↗
Biomedical subjects
Holger Bourquain
Publications and source records attributed to Holger Bourquain.
Impact of virtual tumor resection and computer-assisted risk analysis on operation planning and intraoperative strategy in major hepatic resection.
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.
Adult↗
Evaluation of accuracy in MS lesion volumetry using realistic lesion phantoms.
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.
Adult↗
Three-dimensional visualization and virtual simulation of resections in pediatric solid tumors.
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.
Child↗
Surgical impact of computerized 3D CT-based visualizations in living donor liver transplantation.
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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