DOI

10.17077/etd.3ab61i70

Document Type

Dissertation

Date of Degree

Fall 2016

Degree Name

PhD (Doctor of Philosophy)

Degree In

Electrical and Computer Engineering

First Advisor

Milan Sonka

First Committee Member

Milan Sonka

Second Committee Member

Andreas Wahle

Third Committee Member

Edwin L Dove

Fourth Committee Member

Punam Saha

Fifth Committee Member

Mona K Garvin

Abstract

Coronary atherosclerosis is by far the most frequent cause of ischemic heart disease. Intravascular ultrasound (IVUS) along with virtual histology (VH) is a useful tool for quantification of coronary plaque buildup and provides new insights into the diagnosis of coronary disease. Rupture of vulnerable plaque causing acute coronary syndromes, coronary remodeling maintaining lumen size and plaque phenotype revealing pathological severity are among the most important topics related to atherosclerosis. In this thesis, variations of IVUS-VH-derived thin-cap fibroatheroma (TCFA) definitions are proposed to evaluate the plaque rupture, which is further analyzed in a layered manner; statins effects on coronary remodeling are comprehensively assessed with the implementation of automated IVUS segmentation and registration of IVUS pullbacks based on baseline and 1-year followup datasets; plaque phenotypes are determined and analyzed morphologically and compositionally on segmental basis using the same serial datasets.

In addition, our research involves another important coronary disease — coronary allograft vasculopathy (CAV) which is a frequent complication of heart transplantation (HTx). Another intra-coronary imaging modality — intravascular optical coherence tomography (IVOCT) for quantifying CAV is involved. We present an optimal and automated 3-D graph search approach for the simultaneous IVOCT multi-layer segmentation by transforming the 3-D segmentation problem into finding a minimum-cost closed set in a weighted graph. Furthermore, a computer-aided just-enough-interaction refinement method is proposed to help achieve fully satisfactory 3-D segmentation of IVOCT images. We believe this is the first work that provides a fast, efficient and accurate solution for IVOCT multi-layer assessment in the context of CAV.

The major contributions of this thesis are: (1) Proving that IVUS-VH-derived TCFA prevalence may be overestimated, and elucidating the potential loss of plaque material during rupture, (2) providing a comprehensive understanding of remodeling in the context of both changing the remodeling direction and changing the remodeling extent, and demonstrating the statin therapy effects on remodeling across patients, based on automated segmentation of IVUS images and registration of serial data, (3) showing that the pathological intimal thickening is the most active plaque phenotype in terms of plaque composition changes and plaque vulnerability progression, and (4) developing and validating a method for multi-layer 3-D segmentation of IVOCT images within a novel interactive environment.

Public Abstract

Coronary atherosclerosis is the most frequent cause of ischemic heart disease. Intravascular ultrasound (IVUS) along with virtual histology (VH) is a useful imaging modality for quantification of atherosclerosis buildup. In this thesis, variations of IVUS-VH-derived thin-cap broatheroma (TCFA) definitions are proposed to evaluate plaque rupture causing acute coronary syndromes. It is proved that IVUS-VH-derived TCFA prevalence may be overestimated, and the potential loss of plaque material during rupture is elucidated as well in a layered analysis. With the implementation of automated segmentation of IVUS images and automated registration of baseline and 1-year followup datasets, statins therapy effects on coronary remodeling, a compensatory process in response to plaque progression, are comprehensively assessed in the context of both remodeling direction and remodeling extent. Additionally, plaque phenotypes revealing pathological severity of atherosclerosis are analyzed morphologically and compositionally on segmental basis using the same serial datasets, showing that pathological intimal thickening is the most active phenotype in terms of plaque composition changes and plaque vulnerability progression. Our research also involves another important coronary disease, coronary allograft vasculopathy (CAV), which is a frequent complication of heart transplantation. High-resolution imaging modality | intravascular optical coherence tomography (IVOCT) for quantifying CAV is utilized. We present and validate an optimal and automated 3-D graph search approach for simultaneous multi-layer segmentation of IVOCT images. Furthermore, a computer-aided just-enough-interaction refinement method is proposed to help achieve fully satisfactory results.

Keywords

coronary allograft vasculopathy, coronary atherosclerosis, intravascular optical coherence tomography, intravascular ultrasound, remodeling, thin-cap fibroatheroma

Pages

xii, 98 pages

Bibliography

Includes bibliographical references (pages 90-98).

Comments

This thesis has been optimized for improved web viewing. If you require the original version, contact the University Archives at the University of Iowa: http://www.lib.uiowa.edu/sc/contact/

Copyright

Copyright © 2016 Zhi Chen

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