Medicine and Health Sciences Commons^™

Structure And Function Of Long-Covid Evaluated Using Pulmonary Imaging, Harkiran Kaur Kooner

Electronic Thesis and Dissertation Repository

The COVID-19 pandemic has resulted in millions of global respiratory infections, ranging in severity from asymptomatic to fatal. One of the many consequences of the pandemic is the emergence of long-COVID, which is an umbrella term used to describe the long-term sequelae and poor quality-of-life following recovery from acute COVID-19 infection. However, the pathophysiology and mechanisms responsible for the heterogenous manifestation of long-COVID remain poorly understood. Hyperpolarized ¹²⁹Xe magnetic resonance imaging (MRI) provides a non-invasive and radiation-free method to regionally visualize and quantify inhaled gas distribution and ventilation in vivo. A strong foundation for the use of pulmonary …

Feasibility And Clinical Value Of 3-Dimensional Myocardial Deformation Analysis By Computed Tomography In Transcatheter Aortic Valve Replacement Patients, Mohamad Rabbani

Electronic Thesis and Dissertation Repository

Purpose: Multi-phase computed tomography angiography (CTA) for the pre-procedural planning of TAVR presents a unique opportunity to assess 3D myocardial biomechanics. This study aimed to assess the feasibility and predictive utility of 3D myocardial deformation analysis (3D-MDA) based principal strain to predict heart failure or death following TAVR using pre-procedural, multi-phase computed tomography angiography (CTA) datasets.

Methods: Two hundred and five patients undergoing pre-TAVR multi-phase gated CTA followed by successful TAVR were retrospectively identified. Whole heart 3D mesh chamber models were generated followed by 3D-MDA of the left ventricle (LV) to determine global LV minimum principal strain (minPS) for endocardial, …

Structure And Function Of Asthma Evaluated Using Pulmonary Imaging, Rachel L. Eddy

Electronic Thesis and Dissertation Repository

Asthma has been understood to affect the airways in a spatially heterogeneous manner for over six decades. Computational models of the asthmatic lung have suggested that airway abnormalities are diffusely and randomly distributed throughout the lung, however these mechanisms have been challenging to measure in vivo using current clinical tools. Pulmonary structure and function are still clinically characterized by the forced expiratory volume in one-second (FEV₁) – a global measurement of airflow obstruction that is unable to capture the underlying regional heterogeneity that may be responsible for symptoms and disease worsening. In contrast, pulmonary magnetic resonance imaging (MRI) …

Texture Analysis And Machine Learning To Predict Pulmonary Ventilation From Thoracic Computed Tomography, Andrew Westcott

Electronic Thesis and Dissertation Repository

Chronic obstructive pulmonary disease (COPD) leads to persistent airflow limitation, causing a large burden to patients and the health care system. Thoracic CT provides an opportunity to observe the structural pathophysiology of COPD, whereas hyperpolarized gas MRI provides images of the consequential ventilation heterogeneity. However, hyperpolarized gas MRI is currently limited to research centres, due to the high cost of gas and polarization equipment. Therefore, I developed a pipeline using texture analysis and machine learning methods to create predicted ventilation maps based on non-contrast enhanced, single-volume thoracic CT. In a COPD cohort, predicted ventilation maps were qualitatively and quantitatively related …

Applications Of Ct Perfusion-Based Triaging And Prognostication In Acute Ischemic Stroke, Eric A. Wright

Electronic Thesis and Dissertation Repository

CT Perfusion (CTP) is a minimally invasive imaging technique that aids acute ischemic stroke (AIS) triage and prognostication by determining tissue viability based on hemodynamic parameters. The goals of this research are to determine: 1) CTP thresholds for estimation of infarct and penumbra volume, 2) how CTP scan duration impacts infarct and penumbra volume estimates, and 3) reliability of CTP for predicting functional outcomes following intra-arterial therapy (IAT).

Chapter 2 introduced an experimental study for determining ischemia-time dependent thresholds for brain infarction using multimodal imaging in a porcine stroke model that is easier to implement than previous large animal stroke …

High Performance Optical Computed Tomography For Accurate Three-Dimensional Radiation Dosimetry, Kurtis Hendrik Dekker

Electronic Thesis and Dissertation Repository

Optical computed tomography (CT) imaging of radiochromic gel dosimeters is a method for truly three-dimensional radiation dosimetry. Although optical CT dosimetry is not widely used currently due to previous concerns with speed and accuracy, the complexity of modern radiotherapy is increasing the need for a true 3D dosimeter. This thesis reports technical improvements that bring the performance of optical CT to a clinically useful level. New scanner designs and improved scanning and reconstruction techniques are described.

First, we designed and implemented a new light source for a cone-beam optical CT system which reduced the scatter to primary contribution in CT …

Radiomics For Response Assessment After Stereotactic Radiotherapy For Lung Cancer, Sarah A. Mattonen

Electronic Thesis and Dissertation Repository

Stereotactic ablative radiotherapy (SABR) is a guideline-specified treatment option for patients with early stage non-small cell lung cancer. After treatment, patients are followed up regularly with computed tomography (CT) imaging to determine treatment response. However, benign radiographic changes to the lung known as radiation-induced lung injury (RILI) frequently occur. Due to the large doses delivered with SABR, these changes can mimic the appearance of a recurring tumour and confound response assessment. The objective of this work was to evaluate the accuracy of radiomics, for prediction of eventual local recurrence based on CT images acquired within 6 months of treatment. A …

Hyperpolarized 3he Magnetic Resonance Imaging Phenotypes Of Chronic Obstructive Pulmonary Disease, Damien Pike

Electronic Thesis and Dissertation Repository

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the world. Identifying clinically relevant COPD phenotypes has the potential to reduce the global burden of COPD by helping to alleviate symptoms, slow disease progression and prevent exacerbation by stratifying patient cohorts and forming targeted treatment plans. In this regard, quantitative pulmonary imaging with hyperpolarized 3He magnetic resonance imaging (MRI) and thoracic computed tomography (CT) have emerged as ways to identify and measure biomarkers of lung structure and function. 3He MRI may be used as a tool to probe both functional and structural properties of the lung …

Non-Invasive Determination Of Pre-Clinical Markers Of Cardiovascular Diseases In Low Birth Weight And Maternal Western Diet Guinea Pig Offspring Exposed To A Postnatal Western Diet, Jacky Chiu

Electronic Thesis and Dissertation Repository

Low birth weight (LBW), and maternal Western Diet (WD) consumption have both been independently implicated to increase the risk of developing cardiovascular diseases (CVDs) in later life. These fetal programmed risks are also believed to exacerbate the effects of a postnatal WD pattern. Therefore, resulting in the development of pre-clinical markers of CVDs, such as insulin resistance (IR), coronary circulation disruptions. This thesis aimed to elucidate the roles of sub-optimal in utero growth through placental insufficiency, or chronic maternal WD consumption, and postnatal WD consumption on the long-term programming of CVDs in a guinea pig model. Early pre-clinical markers of …