Ventilation and Perfusion in Asthmatics

Assess regional changes to perfusion and ventilation from inhaled corticosteroid (ICS) and Fast-acting beta-antagonist (FABA) among adult asthmatics using radiographically derived estimates of regional ventilation (V-distribution), ventilation defect percentage (VDP), and ventilation heterogeneity (VH).

Inclusion Criteria: * Physician diagnosis of asthma * Baseline Forced Expiratory Volume in 1 Second (FEV1) \< 80% of predicted, with reversibility (10%) on post-bronchodilator spirometry * Adults, 18-75 years of age * Long-term inhaled controller medication consisting of or including an Inhaled corticosteroids (ICS) at a steady dose for at least 3 months before enrollment Exclusion Criteria: * Current cigarette smoking or a past history of \>10 pack-year smoking * Current nicotine vaping * Pregnant and breast-feeding women * Respiratory infection within 4 weeks of proposed study date * Forced Expiratory Volume in 1 Second (FEV1) \< 50% * Inhaled corticosteroids (ICS)/fast-acting beta agonist (FABA) intolerance * Use of beta-blockers * Use of systemic glucocorticosteroids or oral methyl-xanthines within 30 days of planned study visit.