Medicine and Health Sciences Commons^™

Novel 129xe Magnetic Resonance Imaging And Spectroscopy Measurements Of Pulmonary Gas-Exchange, Alexander M. Matheson

Electronic Thesis and Dissertation Repository

Gas-exchange is the primary function of the lungs and involves removing carbon dioxide from the body and exchanging it within the alveoli for inhaled oxygen. Several different pulmonary, cardiac and cardiovascular abnormalities have negative effects on pulmonary gas-exchange. Unfortunately, clinical tests do not always pinpoint the problem; sensitive and specific measurements are needed to probe the individual components participating in gas-exchange for a better understanding of pathophysiology, disease progression and response to therapy.

In vivo Xenon-129 gas-exchange magnetic resonance imaging (¹²⁹Xe gas-exchange MRI) has the potential to overcome these challenges. When participants inhale hyperpolarized ¹²⁹Xe gas, it …

Unravelling The Subfields Of The Hippocampal Head Using 7-Tesla Structural Mri, Jordan M. K. Dekraker

Electronic Thesis and Dissertation Repository

Probing the functions of human hippocampal subfields is a promising area of research in cognitive neuroscience. However, defining subfield borders in Magnetic Resonance Imaging (MRI) is challenging. Here, we present a user-guided, semi-automated protocol for segmenting hippocampal subfields on T2-weighted images obtained with 7-Tesla MRI. The protocol takes advantage of extant knowledge about regularities in hippocampal morphology and ontogeny that have not been systematically considered in prior related work. An image feature known as the hippocampal ‘dark band’ facilitates tracking of subfield continuities, allowing for unfolding and segmentation of convoluted hippocampal tissue. Initial results suggest that this protocol offers sufficient …

Pulmonary Imaging To Better Understand Asthma, Sarah Svenningsen

Electronic Thesis and Dissertation Repository

Asthma is characterized using the spirometry measurement of the forced expiratory volume in one second (FEV₁). Simple and inexpensive, FEV₁ provides a global estimate of lung function but this metric cannot regionally identify airways responsible for airflow limitation, asthma symptoms or control. Work that brought about an understanding that airway abnormalities are heterogeneously distributed within the lung in asthma patients has motivated the development of pulmonary imaging approaches, such as hyperpolarized helium-3 (³He) and xenon-129 (¹²⁹Xe) magnetic resonance imaging (MRI). These methods provide a way to visualize and quantify lung regions accessed by …