Peitgen, Heinz-Otto
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Item-typ:Veröffentlichung, Liver Segmentation and its Application to Hepatic Interventions(2012-09-24); ; ; The thesis addresses the development of an intuitive and accurate liver segmentation approach, its integration into software prototypes for the planning of liver interventions, and research on liver regeneration. The developed liver segmentation approach is based on a combination of the live wire paradigm and shape-based interpolation. Extended with two correction modes and integrated into a user-friendly workflow, the method has been applied to more than 5000 data sets. The combination of the liver segmentation with image analysis of hepatic vessels and tumors allows for the computation of anatomical and functional remnant liver volumes. In several projects with clinical partners world-wide, the benefit of the computer-assisted planning was shown. New insights about the postoperative liver function and regeneration could be gained, and most recent investigations into the analysis of MRI data provide the option to further improve hepatic intervention planning.Dissertation471 544 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Complexity Reduction in Image-Based Breast Cancer Care(2014-09-16); ; ; The diversity of malignancies of the breast requires personalized diagnostic and therapeutic decision making in a complex situation. This thesis contributes in three clinical areas: (1) For clinical diagnostic image evaluation, computer-aided detection and diagnosis of mass and non-mass lesions in breast MRI is developed. 4D texture features characterize mass lesions. For non-mass lesions, a combined detection/characterisation method utilizes the bilateral symmetry of the breast s contrast agent uptake. (2) To improve clinical workflows, a breast MRI reading paradigm is proposed, exemplified by a breast MRI reading workstation prototype. Instead of mouse and keyboard, it is operated using multi-touch gestures. The concept is extended to mammography screening, introducing efficient navigation aids. (3) Contributions to finite element modeling of breast tissue deformations tackle two clinical problems: surgery planning and the prediction of the breast deformation in a MRI biopsy device.Dissertation530 113 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Morphological Volumetry : Theory, Concepts, and Application to Quantitative Medical Imaging(2005-03-11); ; ; This thesis brings quantitative methods on complex medical image data closer to clinical routine, and bridges the gap between manual and automated processing. Efficient and effective image segmentation methods are described, and applied to currently insufficiently solved problems that are relevant for medical diagnosis and therapy monitoring. The methods are designed to be suitable for software assistants that meet the requirements imposed by a quantitative analysis in clinical imaging: Applicability regarding the required hardware and acquisition protocols, as well as an effective and intuitive user control, robustness to variations of image quality and also of anatomy and pathology, precision of all derived quantitative measures, sensitivity with respect to relevant changes of the examined structures, and efficiency in order to be applicable to very large data sets on standard hardware. The first part of this thesis describes novel methods that build upon and extend the morphological watershed transform that is known as the key concept for image segmentation in Mathematical Morphology, with applications to brain segmentation in magnetic resonance imaging as well as bone removal in computed tomography and CT angiography. The second part focuses on quantitative image analysis in general, as well as the volumetry of specific neuroanatomical structures in particular. Morphological Volumetry is proposed as a framework for the reliable volumetric quantification of complex three-dimensional structures found in tomographic medical images, combining the extended watershed transform and automated histogram analysis. In cooperation with clinical and industrial partners, the proposed methods were successfully evaluated on a great variety of patient and volunteer images, as well as on software phantoms. The methods have shown potential to improve medical diagnosis and quantitative therapy monitoring and to enhance objectivity in medical image analysis in various instances.Dissertation379 204 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Quantitative Analysis of Lung Morphology and Function in Computed Tomographic Images(2008-07-07); ; ; In clinical lung radiology, primary cancer, metastatic disease, and parenchymal diseases such as emphysema or fibrosis play central roles. In the examination of these and other lung diseases, Computed Tomography (CT) is the reference imaging modality. In current clinical routine, the standard procedure for examining lung CT data is visual inspection. However, visual inspection not only requires a large amount of concentration and time, but is also limited to a solely qualitative and highly subjective image assessment. This thesis is concerned with research, development, and evaluation of new methods in digital image processing that assist the radiologist in performing a quantitative CT-based assessment of pulmonary morphology and function in patients with parenchymal or tumorous lung disease. To support the regional analysis of the lung parenchyma in patients with parenchymal disease, fast robust methods for the automated segmentation of the lungs and their subsequent subdivision into lung lobes are developed. The lobe segmentation relies on an analysis of the vessel and airway anatomy rather than explicitly detecting the lobe-separating fissures. This makes it applicable to cases in which the fissures are concealed by pathology, incomplete, or missing. The new methods are extensively evaluated on a large heterogeneous set of pathological test cases to demonstrate their potential in the analysis of clinically relevant patient data. In the field of lung tumor analysis, previous research focused on supporting lung cancer screening by providing automatic segmentation methods for the volumetry of small pulmonary nodules. The algorithm presented in this thesis is designed to perform a fast, automated segmentation of small nodules and large lung metastases alike, and to be thereby equally suitable for application in the diagnosis of early stage lung cancer and monitoring of chemotherapy response. This flexibility is achieved by the introduction of an optimal opening procedure that, based on realistic model assumptions, permits a theoretically guaranteed separation of connected vasculature. Still, segmentation is merely the first step to volume measurement: The imaging variabilities caused by slight variations of the acquisition protocol are shown to severely impair clinical applicability of conventional segmentation-based volumetry approaches. This thesis proposes a volume quantification technique that compensates for these variabilities by exploiting the knowledge gained during segmentation and performing a selective volume averaging analysis at the tumor boundaries. Evaluation is performed on both in-vivo metastases and phantom nodules to demonstrate the robustness of the new segmentation method as well as the validity and significantly increased reproducibility of the developed volumetry technique.While the technical soundness of the developed solutions is crucial, clinical impact can only be achieved if attention is also paid to practical applicability, i.e., the capability of running robustly under clinical conditions and of blending in smoothly with the demanding radiological workflow. Thus, the developed algorithms are integrated into a software prototype that can be conveniently used by clinicians. In addition to the technical evaluation, several evaluation studies are performed by clinical experts to verify applicability and clinical usefulness of the novel methods.Dissertation473 153 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Computer-Assisted Diagnosis and Therapy Planning in Coronary Artery Disease Based on Cardiac CT and MRI(2012-08-31); ; ; State-of-the-art imaging with CT and MRI allows the acquisition of image data for the evaluation of coronary pathologies, myocardial perfusion, detection of infarctions and myocardial function. Thus, information about the cause, effect and potential progression of coronary artery disease is available. The interpretation of the available image data is a difficult task due to the differences in coverage, resolution and contrast types. The goal of the presented work was the development and evaluation of a set of image processing methods to support this task. These methods include registration methods for the alignment of different datasets as well as compensation methods for the motion, which is caused by breathing or myocardial contraction. Other image processing tasks are the segmentation of the coronary arteries and the classification of the myocardium according to its viability status. The proposed methods are integrated into clinically applicable software prototypes and evaluated with phantom and animal datasets as well as with data from clinical routine. The results show a clear benefit for the diagnosis and therapy prognosis of CAD patients based on CT and MRI image data.Dissertation395 305 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Papierfalten(2006-12-13); ; ; In this thesis the properties of the paperfolding sequence are investigated with an emphasis on the application in mathematical education.In ten chapters the sequence is examined in different ways: first and foremost as a sequence of symbols produced by folding a strip of paper repeatedly in halves. The geometric point of view gives a curve that is space-filling and a fractal, known as the Dragon-curve or the Heighway-dragon. This is connected to iterated function-systems (IFS). If the unfolding angle is slightly larger than 90 degrees intersections of the curve occur. This is investigated in detail in chapter 9. The sequence can also be seen as the binary representation of a number of the unit interval. Then the problem of an easy calculation arises. The paperfolding sequence is one of the foremost examples for an automatic sequence, which is looked at in chapter 7. In the last chapter some classic curves are investigated if they can be generated by paperfolding.Dissertation948 1647