Longitudinal Study of Helium-3 and Xenon-129 Magnetic Resonance Imaging

COPD patients will be stratified into four groups: Gold Stage 0, Gold Stage I, Gold Stage II, and Gold Stage III. During a single 2-2 ½ hour visit, patient subjects will perform some or all of: 1) spirometry pre-and-post salbutamol and plethysmography, Lung Clearance Index, Airway Oscillometry (Airwave Oscillometry measures the mechanics of the respiratory system by superimposing a gentle multi-frequency airwave onto the patient's respiratory airflow. Measurements take no longer than 16 seconds and the patient simply breathes normally into a disposable mouthpiece for the duration of the test.) 2) 6MWT (including Borg questionnaire pre-and post-walk), 3) health status evaluation using a self-administered SGRQ and MMRC (Modified Medical Research Council dyspnea scale) 4) CT, and, 5) 3He MRI. Subjects will first provide written informed consent and then be screened for MRI compatibility and will complete: 1) Spirometry pre-salbutamol, SGRQ after inhaling 2-4 puffs (200-400μg) of the short-acting bronchodilator (eg. Salbutamol), 2) MRI, 3) CT. (Subjects will be taken by wheelchair to and from University Hospital, LHSC to decrease the potential for dynamic hyperinflation), 4) plethysmography and spirometry within 1 ½ hours of salbutamol. Vital signs will be performed. Because it is impossible to schedule imaging at the same time-point post-bronchodilator, subjects will be randomized to MR or CT 30 minutes post-salbutamol (1:1 ratio), to minimize bias.