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Doctor of Philosophy




Dr. Giles Santyr


Imaging of the lungs using non-ionizing approaches such as hyperpolarized 3He and 129Xe magnetic resonance imaging (MRI) is a useful tool both for research and clinical applications. This work focused on development of 129Xe MRI techniques to investigate inflammation in rat lungs. A rodent model of inflammation, specifically radiation-induced lung injury (RILI) was developed using a collimated 60Co source. A quantitative MRI technique measuring absolute ventilated lung volume (|VLV|) was performed using 129Xe and 3He. Following a comparison between |VLV| values obtained from rats using the previously established 3He method and those obtained with 129Xe, the usefulness of 129Xe for future investigations of |VLV| in rodent models of inflammation was demonstrated. 129Xe dynamic spectroscopy was used to investigate the predicted gas transfer deficiencies represented by xenon gas transfer time constants (TTr) for 129Xe dissolved within tissue (TTr_tissue) and blood (TTr_RBC) in a model of RILI. Increases in TTr_tissue were measured at two weeks post irradiation together with decreases in the partial pressure of arterial oxygen (paO2), consistent with the assumption of gas exchange impairment. Finally, a novel minimally invasive intubation technique was investigated to support longitudinal studies in rodent models of inflammation. This serves to reduce the overall numbers of animals used within a given study as well as reduce uncertainty in measurements due to biological differences in end-point studies. These investigations lay the groundwork for future reliance on 129Xe for hyperpolarized imaging studies of the lung as well as strengthening the methodology for future longitudinal investigations of inflammation.

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