Non-invasive cardiac magnetic resonance imaging techniques for assessment of myocardial fibrosis

  • Author / Creator
    Pagano, Joseph
  • While there may be numerous underlying origins, myocardial fibrosis is a common, unifying finding in various forms of heart disease. Unfortunately, its presence goes beyond simply being a herald of myocardial injury. The alterations in the extracellular space lead to abnormalities in both systolic and diastolic heart function and have been associated with adverse outcomes such as hospitalizations, heart failure, arrhythmias, and death. The gold standard assessment for myocardial fibrosis involves histopathological assessment of tissue acquired either at autopsy or via invasive endomyocardial biopsy, which is not without associated risks of complications.Cardiac magnetic resonance imaging (MRI) provides clinicians and researchers a powerful and versatile imaging system to help in their endeavours to better understand and characterize how the heart develops and adapts to numerous stresses and insults. This is particularly true with recent developments in the non-invasive assessment of myocardial fibrosis using MRI based T1-mapping techniques. The goal of the thesis was to explore the impact of physiological and pathological stresses on the heart, through the use of MRI T1-mapping.In particular, the effects of aging, sex, and risk factors for the development of heart failure were studied. It was determined that there were no significant alterations in T1-mapping markers of myocardial fibrosis associated with the aging process. Importantly, however, there do appear to be sex differences in the response to risk factors for heart failure. Next, different distinct phenotypes of heart failure were studied to gain insight into differences in remodeling that may contribute to the observed functional and clinical heterogeneity.While much of the focus is on the heart’s left ventricle, it cannot be forgotten that the right ventricle may be involved additionally, or even as the primary site of pathology. In patients with Anderson-Fabry disease, characterized by interstitial deposition of glycosphingolipids, the development of right ventricular thickening is driven by the same infiltrative process that occurs in the left ventricle. This contrasts with hypertrophy and myocardial fibrosis that is occurring in response to increased right ventricular afterload, as seen in pulmonary hypertension.Finally, a novel approach to T1-mapping was developed to overcome some limitations in current T1-mapping techniques, allowing for increased spatial resolution and imaging at end-systole, at which point in time there are more pixels across the ventricular wall. This new technique, based on a lookup table approach using image ratios, was validated by means of numerical simulations, phantom experiments, and in vivo.Cardiac MRI provides insight into myocardial form and function that may otherwise require multiple, possibly invasive, approaches. It has been instrumental in developing our understanding of the normal and diseased heart. Further studies, expanding on work presented here, will be important in providing new knowledge and techniques critical to moving the field forward.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
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