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Permanent link (DOI): https://doi.org/10.7939/R3GG82

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Quantitative Imaging of Diastolic Function using Cardiac Magnetic Resonance Imaging Open Access

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Other title
Subject/Keyword
magnetic resonance imaging
cardiac
diastolic function
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Cheng Baron, June
Supervisor and department
Thompson, Richard (Department of Biomedical Engineering)
Examining committee member and department
Macgowan, Christopher (Department of Medical Biophysics, University of Toronto)
Beaulieu, Christian (Department of Biomedical Engineering)
Thompson, Richard (Department of Biomedical Engineering)
Paterson, Ian (Division of Cardiology)
Wilman, Alan (Department of Biomedical Engineering)
Haykowsky, Mark (Faculty of Rehabilitation Medicine)
Department
Medical Sciences-Biomedical Engineering
Specialization

Date accepted
2012-12-18T14:15:27Z
Graduation date
2013-06
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Diastolic dysfunction is the primary cause of 40–50% of all heart failure cases and is a contributing factor in many cardiac conditions, resulting from delayed or slowed muscle relaxation, increased stiffness of the relaxed heart or from poor systolic function which reduces the elastic recoil of the heart. The study of diastolic function has been hampered by a lack of simple, quantitative, parameters describing diastolic performance. The current standard of evaluation consists of echocardiography-derived blood and tissue velocities. Magnetic resonance imaging (MRI) provides better spatial coverage and soft tissue contrast, but is relatively unexplored in the context of diastolic function. Goals of this thesis were to improve current and develop new quantitative measures of diastolic function using MRI. Left ventricular deformation during isovolumic relaxation was studied to reveal that measured changes in left ventricular volume during this interval reflect changes in myocardial strain and are balanced by the inward bowing of the mitral valve leaflets which maintains the isovolumic condition. Next, aspects of the filling portion of the cardiac cycle were studied including mitral blood velocity and flow, left atrial propagation velocity and atrio-ventricular pressure gradients. Mitral blood velocity and flow were found to have distinct time-courses that become more similar with increasing severity of diastolic dysfunction. Velocity propagation, a wave-like pressure wave phenomenon, was observed in the left atrium during systole, early filling and atrial contraction, providing a new measure of diastolic function reflecting atrial stiffness and pressure. Atrio-ventricular pressure gradients however, were not found to provide additional information beyond blood velocity measures. Finally, there is growing interest in measuring systolic strain in the presence diastolic dysfunction with preserved ejection fraction, where strains appear abnormal despite normal volumetric function. Conventional MRI-derived strain requires specialized acquisition protocols and onerous post-processing. A method was developed to measure strains from standard anatomical MRI. MRI is a promising tool for the comprehensive characterization of diastolic function. However, this field of study is still relatively un-established and further studies, similar to those presented here, in larger patient groups are necessary to establish the role of MRI for diastolic function in research and clinically.
Language
English
DOI
doi:10.7939/R3GG82
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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