Author : Miranda Kirby
Release : 2013
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Kind : eBook
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Book Synopsis Pulmonary Structure and Function in Chronic Obstructive Pulmonary Disease Evaluated Using Hyperpolarized Noble Gas Magnetic Resononance Imaging by : Miranda Kirby

Download or read book Pulmonary Structure and Function in Chronic Obstructive Pulmonary Disease Evaluated Using Hyperpolarized Noble Gas Magnetic Resononance Imaging written by Miranda Kirby. This book was released on 2013. Available in PDF, EPUB and Kindle. Book excerpt: Chronic obstructive pulmonary disease (COPD) is the 4th leading cause of death worldwide and accounts for the highest rate of hospital admission s in Canada . The need for sensitive regional and surrogate measurements of lung structure and function in COPD continues to motivate the development of non-radiation based and sensitive imaging approaches, such as hyperpolarized helium-3 (3 He) and xenon-129 (129 Xe) magnetic resonance imaging (MRI). The static ventilation images acquired using these approaches allows us to directly visualize lung regions accessed by the hyperpolarized gas during a breath-hold, as well as quantify the regions without signal referred to as the percentage of the thoracic cavity occupied by ventilation defects (VDP). The lung micro-structure can also be probed using diffusion-weighted imaging which takes advantage of the rapid diffusion of 3 He and 129 Xe atoms to generate surrogate measurements of alveolar size, referred to as the apparent diffusion coefficient (ADC). Here we evaluated COPD lung structure and function using hyperpolarized gas MRI measurements longitudinally, following treatment and in early disease. In COPD ex-smokers, we demonstrated 3 He VDP and ADC worsened significantly in only 2 years although there was no change in age-matched healthy volunteers, suggestive of disease progression. We also evaluated COPD ex-smokers pre - and post - bronchodilator and showed regional improvements in gas distribution following bronchodilator therapy regardless of spirometry-based responder classification ; the ADC measured in these same COPD ex-smokers also revealed significant reductions in regional gas trapping post-bronchodilator. Although 3 He MRI has been more widely used, the limited global quantities necessitates the transition to hyperpo larized 129 Xe, and therefore we directly compared 3 He and 129 Xe MRI in the same COPD ex - smokers and showed significantly greater gas distribution abnormalities for 129 Xe compared to 3 He MRI that were spatially and significantly related to lung regions with elevated ADC . Finally, we demonstrated that ex - smokers with normal spirometry but abnormal diffusion capacity of the lung for carbon monoxide (D L CO) ha d significantly worse symptoms, exercise capacity and 3 He ADC than ex - smokers with normal D L CO . These important findings indicate that hyperpolarized gas MRI can be used to improve our understanding of lung structural and functional changes in COPD.