Proton image overlaid with xenon image (red) of a subject with asthma. Arrow indicates an area with ventilation defect.

Asthma is a chronic pulmonary disease, characterized by acute and mostly reversible episodes of airflow limitation and airway hyper-responsiveness that lead to airway remodeling. The Santyr lab is working with scientists and clinicians in the Department of Respiratory Medicine at SickKids to develop and test MRI methods for measurement of regional disease in children afflicted by asthma.

The lung clearance index (LCI) is a novel method for measurement of lung physiology, derived from inert gas multiple breath washout (MBW) test. It is performed during quiet breathing by the child and thus is less variable than traditional pulmonary function tests involving forced expiration maneuvers. LCI has also been shown to be feasible in infants. LCI reflects global ventilation inhomogeneity and is a highly sensitive marker of early obstructive lung disease. This project is investigating the correlation between LCI and quantitative regional analysis of ¹²⁹Xe MRI in paediatric healthy volunteers and patients with both well and poorly-controlled asthma.