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Estimation of mechanical properties of the cancellous bone tissue of the proximal tibia
Leinweber, Vít ; Valášek, Jiří (referee) ; Marcián, Petr (advisor)
This bachelor thesis is focused on the determination of mechanical properties of cancellous bone tissue of proximal tibia. In the beginning of the work there is theoretical part which consists of a description of the tibia anatomy from macroscopic and microscopic view, treatise on the bone tissue growth, influences affecting the bone tissue growth and description of mechanical properties of the bone tissue. In the end of the theoretical part there is a detailed review of related literature to this work. In the practical part morphometric parameters are measured using software ImageJ and plugin BoneJ. The process of creating a computational model is described and results of mechanical properties are presented. Regression models of mechanical properties and histomorphometric parameters are created from these results.
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Computational simulation of the compression test of the open cell metal foam
Homola, Václav ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
The thesis presents computational simulation of compression test of a nickel foam and the 3D reconstruction of micro-CT images was utilized to generate the foam’s model of geometry. Explicit FEM is used to simulate compression test using software tool LS-DYNA and the stress–deformation curve is obtained together with deformed model’s mesh used for subsequent analysis. Sensitivity analyses were performed to configure the model and ensure best fit with values obtained during real-life experiment. The ANSYS Classic environment was then used to simulate tensile test of the foam compressed to various thicknesses. The tensile moduli in three mutually perpendicular directions of nickel foam were computed and the results were compared to experimental values as well. The results of tensile test simulation revealed considerable anisotropy of the foam’s elastic behavior. It can be said that the measured experimental data correspond very well with the elastic properties obtained from simulation up to certain level of compression. Analysis of the relationship between the element size and tensile moduli showed a significant difference between fine and coarse mesh. The optimal level of discretization and the overall model configuration ensuring high level of accuracy is proposed in this thesis.
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Preclinical use and critical evaluation of micro-CT from the perspective of oral and maxillofacial surgery.
Bartoš, Martin ; Foltán, René (advisor) ; Naňka, Ondřej (referee) ; Bulik, Oliver (referee)
The preclinical imaging method micro-CT (microtomography) allows the visualization and quantification of the structure of samples at a resolution of micrometers. Its' importance is increasing globally. In addition to several advantages (non-destructive, the possibility of direct 3D analysis, time efficiency, etc.), micro-CT also has some significant limitations (problematic validation of results, image artifacts, significant influence of image modifications, etc.). This thesis focuses on the application of micro-CT in the field of research and development of metallic and non-metallic materials promoting bone healing with their possible clinical applications. The first part addresses the limitations of micro-CT through several studies. A comparison of pore sizes in biomaterials utilizing scanning electron microscopy (SEM) and micro-CT was performed, and the complications of pore size evaluation were presented. SEM image analysis leads to significantly higher values than micro-CT (approximately three times), which allows for comparison of the studies using only one of these methods. Validation of micro-CT 3D analysis results based on calibration phantoms with complex structure, to date, is not possible. We therefore developed software generating phantom datasets of 3D objects with well-defined...
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Blood vessel tree segmentation of the mouse liver in CT data
Smékalová, Veronika ; Odstrčilík, Jan (referee) ; Kolář, Radim (advisor)
The methodology of visualization of soft tissue is in biology and medicine a topic for many years. During this period there were approving many techniques how to achieve accurate and authentic image of the researched object or structure. X-ray computed tomography is very helpful to get this goal but is necessary to improve contrasting techniques as well as the techniques of image post-processing. This thesis deals with imaging soft tissue. Specifically, it focuses on mouse liver contrasting with the artificial resin Microfil. Thesis also describes image processing technique (thresholding and region growing) for the data of the measurement with the goal of the visualization of the sample in 3D.
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Visualization of insect morphological structures using x-ray microtomography and other modern 3D techniques
Rosová, Kateřina ; Prokop, Jakub (advisor) ; Janšta, Petr (referee)
In my bachelor thesis I describe techniques currently used for 3D visualization of morphological structures of insects. Since X-ray microtomography is currently the most attractive option for visualizing internal insect structures, more space is dedicated to its description, but the work includes more innovative techniques. Traditional techniques used in the past decades are not neglected, since they do not lose their importance in the competition of new methods. In the first part the individual methods are presented in terms of their simplified functional mechanisms and the basic steps of creation of 3D reconstructions are described. Techniques are further compared in the text in terms of their usability on different types and sizes of samples, according to the desired final resolution of the visualization, the time required to complete the observation and final visualization and in terms of invasiveness of the techniques. The last chapter summarizes the possibilities of using these innovative methods in entomology based on available studies. Keywords: Insecta, morphology, 3D visualization, SEM, CLSM, MRI, Micro-CT
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The estimation of cross-sectional properties of femur in non-adult individuals: effect of anatomical localization
Čerevková, Simona ; Sládek, Vladimír (advisor) ; Hora, Martin (referee)
Different tracing techniques of the subperiosteal and endosteal contours (manual, automatic, semi-automatic) or their combinations taken along femoral length in adult individuals can produce different values of cross-sectional geometric (CSG) parameters. Various tracing techniques are widely used in CSG studies of non-adult individuals as well, however, the accuracy of CSG parameters estimated along femoral diaphysis is not yet known for non-adult individuals. In this study, we investigate whether the manual tracing of the subperiosteal and endosteal contours taken at 80% of the femoral diaphyseal length in non-adult individuals can be replaced by another type of tracing in relation to CSG parameters estimation. We examine the effect of anatomical localization on accuracy of the CSG parameters estimated in non-adult individuals femora. We digitized the subperiosteal and endosteal contours in the micro-CT scans from femoral diaphyseal cross-sections in Early Medieval sample of non-adult individuals (N = 46). The digitization and computation of CSG parameters were made in Fiji software with EPJMacro implementation. The assessment of estimates' accuracy was expressed by percentage prediction error (%PE) and limits of agreement. Five percent of CSG parameter obtained from manually traced contours was...
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Morphology of the Abdominal Aortic Aneurysm
Eberlová, Lada ; Valenta, Jiří (advisor) ; Stingl, Josef (referee) ; Šebesta, Pavel (referee)
Dissertation Abstract Abdominalaortic aneurysm (AAA) is a serious disease. Its prevalence is in the developed countries about 3%. As an aneurysm is considered a dilatation of all layers of a vessel wall over 3 cm. Majority of AAA are small and asymptomatic, and although the risk of rupture increases with the size of aneurysm sack, even the small aneurysms rupture. The rupture mortaliry ranges about 70 %. Surgical treatment is indicated in the asymptomatic patients in diameter of AAA over 5 cm. The average speed of growth of AAA is 0.3 cm per year, e.g. in the early diagnosed patients there is a several years interval for a pharmacolocical influencing of the progression of this disease. Knowledge of pathogenesis is essential for any targeted pharmacological treatment. Our prospective, non-randomised studies are based on the application of the stereological methods for the histopathological assessment of the AAA samples. The acquired data enable the statistical analysis, including the null hypothesis testing. In our study analyzing the histopathology of AAA aortae of 65 patients (65 walls and 55 thrombi) and 6 normal abdominal aortae from the organ donors we assessed the following parameters: the area fractions of collagen and elastin, and the length density of elastin in intima and media, the area...
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X-ray computed tomography of mouse embryo
Šejnohová, Marie ; Walek, Petr (referee) ; Kolář, Radim (advisor)
The aim of this semestral thesis is to compare the possibilities of available micro-CT systems. Theoretic part of this thesis there deals with possibilities of staining soft tissues and embryos because of enhancement the contrast of micro-CT images. Here follows a description of sources X-ray and detectors of available micro-CT systems. In practice there was realized the staining of embryo in cooperation with Department of histology and embryology in Brno. Then followed a measuring on FSI in Brno, ČVUT in Prague and synchrotron Elettra in Italy. In semestral thesis are described of the thesis there are compared the micro-CT systems and results of measuring embryos by means of presented systems and results are compared.The best results were obtained on micro-CT in Brno, where X-ray tube and flat panel detector were used. This images were used for a segmentation of cartilage olfactory system by means of 3D region growing. From results they were created 3D models for comparison with a manually segmented model. A less accurate results were obtain with the semi-automatic segmentation but this method isn’t too time-consuming.
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On the reliability of microstructural models of trabecular bone with tissue properties from nanoindentation for bone quality assessment
Jiroušek, Ondřej ; Zlámal, Petr
Material properties of trabecular bone can be inversely determined by microstructural finite element (FE) models. The geometry of these models is developed using three-dimensional image data from microfocus Computed Tomography (micro-CT). The reliability of these models to predict the overall elastic properties is influenced by several factor, namely the tissue material properties, resolution of the input images, quality of the segmentation and quality of the FE mesh. This article describes all the aspects of proper and reliable inverse estimation of bone quality using the microstructural models with tissue properties assessed by nanoindentation.
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