Methods for measuring deformation and motion of the human heart in-vivo are crucial in the assessment of cardiac function. Applications ranging from basic physiological research, through early detection of disease to follow-up studies, all benefit from improved methods of measuring the dynamics of the heart. This thesis presents new methods for acquisition, reconstruction and visualization of cardiac motion and deformation, based on magnetic resonance imaging. Local heart wall deformation can be quantified in a strain rate tensor field. This tensor field describes the local deformation excluding rigid body translation and rotation. The drawback of studying this tensor-valued quantity, as opposed to a velocity vector field, is the high dimensionality of the tensor…
Contents
1 Introduction
1.1 Outline of the thesis
1.2 Glossary of terms and abbreviations
2 Cardiac motion
2.1 The cardiac cycle
2.2 The respiratory cycle
2.2.1 Interventricular coupling
2.3 Myocardial deformation
3 Cardiac Magnetic Resonance Imaging
3.1 MRI Principles
3.2 k-space
3.3 k-t sampling
3.4 Temporal resolution
3.4.1 Prospective cardiac gating
3.4.2 Retrospective cardiac gating
3.4.3 TRIADS
3.4.4 Simultaneous resolution of both cardiac and respira-tory cycles
3.5 k-space acquisition order
4 Rapid acquisition
4.1 k-t BLAST
4.1.1 The x-f space
4.1.2 Fast estimation of signal distribution in x-f space
4.1.3 The k-t BLAST reconstruction filter
4.1.4 Implementation details
5 Tensor field visualization
5.1 Glyph visualization
5.2 Noise field filtering
5.2.1 Enhancement
6 Summary of papers
6.1 Paper I: Tensor Field Visualisation using Adaptive Filtering of Noise Fields combined with Glyph Rendering
6.2 Paper II: Five-dimensional MRI Incorporating Simultaneous Resolution of Cardiac and Respiratory Phases for Volumetric
Imaging
6.3 Paper III: k-t
2 BLAST: Exploiting Spatiotemporal Structure in Simultaneously Cardiac and Respiratory Time-resolved Volumetric Imaging
7 Discussion
7.1 Multidimensional imaging
7.2 Using k-t
2 BLAST for respiratory gating
7.3 Costs of sparse sampling
7.3.1 Noise
7.3.2 Temporal fidelity
7.4 Future work
7.4.1 Validation
7.4.2 Tensor field data quality
7.4.3 Optimizing reduction factor versus temporal fidelity
7.4.4 Acquisition of velocity data using k-t
2 BLAST
7.5 Potential impact
Bibliography
Author: Sigfridsson, Andreas
Source: Linköping University
Download URL 2: Visit Now