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Wittek, Andreas: Mechanical and pathophysiological in vivo characterization of the individual aortic wall based on 4D ultrasound imaging. 2020
Inhalt
Title page
Preface
Summary
Zusammenfassung
Contents
Nomenclature
1 Introduction
1.1 Motivation by the abdominal aortic aneurysmrupture risk estimation
1.2 Organization of the thesis
1.3 The heart and the physiological function of thearteries’ elastic properties
1.4 Microstructural elements and compositionof the aortic wall
1.5 Mechanical properties of the aortic wall
1.6 Axial prestretch and residual stresses
1.7 Degenerative changes of the aorta‘s elastic properties with age and pathology
2 Continuum mechanical framework
2.1 Kinematics of finite deformations
2.2 Stress tensors
2.3 Elastic material properties
3 A method for non-invasive fullfield strain measurement
3.1 Ultrasound measurement of aortic wall deformation
3.2 Clinical data acquisition and post-processing
3.3 Deformation metrics based on customized 4D ultrasound wall motion data
3.4 Effects of increased spatial resolution on in vivo strain measurement
3.5 Characteristic size of aortic wall motion in vivoThe
4 In vitro validation of full-field wall motion measurement
4.1 Introduction
4.2 Methods of the in vitro validation study
4.3 Results of the validation study
4.4 Discussion of the validation results
4.5 Limitations of the validation study
5 Comparative Analysis of ascending and abdominal aortic wall motion
5.1 Introduction
5.2 Study collective and in vivo data acquisition
5.3 Statistics
5.4 Multiaxial deformation of the ascending and the abdominal aorta
5.5 Relations between deformation patterns and physiological function
6 Locally varying elastic behavior of human aortae in vivo
6.1 In vivo measures of aortic elasticity in thephysiological range
6.2 The local distensibility coefficient
6.3 Indices for the characterization of the spatial distribution of the local elastic behavior
6.4 Distributions of local elasticity in young, aged and aneurysmal aortic walls
6.5 Discussion and limitations
7 Identification of the orthotropic and hyperelastic constitutive behaviorof aortic walls in vivo
7.1 Introduction
7.2 Assumptions for the patient-specific modeling
7.3 Theoretical basis for constitutive parameter identification in vivo
7.4 Constitutive equation
7.5 Non-invasive in vivo data
7.6 Model-based estimation of systolic in-plane strains
7.7 Constitutive parameter identification strategy
7.8 Numerical verification experiment
7.9 Results of the verification experiment
7.10 Individual constitutive behavior identified based on in vivo data
7.11 Discussion and conclusions
8 Summary and outlook
9 References
Appendix
A. Derivatives of the pseudoinvariants
B. Convergence study for the FE discretization of pressurized aortic segments
C. First approach to a Finite Element Model Updating workflow
D. List of first author publications that were used in this thesis