Abstract #0908

Quantitative Evaluation of Ventilation Dynamics in Asthma During Methacholine Challenge using Hyperpolarized 3He Magnetic Resonance Imaging

Stephen Costella^1,2, Andrew Wheatley¹, David McCormack³, Grace Parraga^1,2

¹Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; ²Graduate Program in Biomedical Engineering, University of Western Ontario, London, Ontario, Canada; ³Medicine, Division of Respirology, University of Western Ontario, London, Ontario, Canada

Pulmonary functional imaging using helium-3 (3He) magnetic resonance imaging (MRI) has provided us with a way to quantitatively evaluate the spatial and temporal functional changes in a variety of respiratory conditions, including asthma. We quantitatively evaluated ventilation defect size and number at baseline, PC20 and after recovery and compared these values with spirometry. Our results suggest that mean defect size is the dominant mechanism for the changes in FEV1 that occur at PC20 as compared to defect count. This provides important new information on the mechanisms involved in asthma exacerbations and insights on prophylaxis to avoid exacerbations.