Estimation of Dynamically Evolving Ellipsoids with Applications to Cardiac Imaging
نویسنده
چکیده
This thesis deals with a method to obtain the ejection fraction of the left ventricle of the heart from a gated set of planar myocardial perfusion images. Ejection fraction is defined as the ratio of the fully contracted left-ventricular volume to the fully expanded left-ventricular volume and is known as an effective gauge of cardiac function. This method is proposed as a safer and more cost effective alternative to currently used radionuclide ventriculographic based techniques. To formulate this estimate of ejection fraction, we employ geometric reconstruction and recursive estimation techniques. The left ventricle is modelled as a threedimensional ellipsoid. Projections of this left ventricular ellipsoid are two-dimensional ellipsoids, which we use to model the left-ventricular outline in the observed myocardial perfusion images. The ellipsoid that approximates the left ventricle is reconstructed using Rauch-Tung Striebel smoothing which combines the observed temporal set of projection images with an evolution model to produce the best estimate of the ellipsoid at any point given all the data. Ejection fraction is calculated from the reconstructed ellipsoids. We study the error introduced in the reconstruction by imperfect knowledge of the ellipsoid dynamics and projection geometry through simulations. In addition, we use simulations to investigate model identification as a method to identify which of two hypothesized models best approximates the true ellipsoid dynamics. Finally, we test these techniques on real myocardial perfusion data. Thesis Supervisor: Alan S. Willsky Title: Professor Thesis Supervisor: W. Clem Karl Title: Research Scientist
منابع مشابه
Estimation of dynamically evolving ellipsoids with applications to medical imaging
The estimation of dynamically evolving ellipsoids from noisy lower-dimensional projections is examined. In particular, this work describes a model-based approach using geometric reconstruction and recursive estimation techniques to obtain a dynamic estimate of left-ventricular ejection fraction from a gated set of planar myocardial perfusion images. The proposed approach differs from current ej...
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