Stephen Costella1,2, Andrew Wheatley1, David McCormack3, Grace Parraga1,2
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.