Missing airways, ventilation defects and conductive airway physiology in asthma.

Competing Interests: Conflict of interest: R.L. Eddy reports grants from Michael Smith Health Research BC, Canadian Respiratory Research Network and the Natural Sciences and Engineering Research Council Canada, consulting fees from VIDA Diagnostics Inc., lecture honoraria from Thorasys Thoracic Medical Systems Inc., travel support from Canadian Institutes of Health Research – Institute of Circulatory and Respiratory Health, and a leadership role as Xenon MRI Clinical Trials Consortium Steering Committee Member, outside the submitted work. G. Parraga reports grants from the Canada Foundation for Innovation and the Natural Sciences and Engineering Research Council Canada, lecture honoraria from GSK, advisory board participation with Polarean and CIHR, and a leadership role as Xenon MRI Clinical Trials Consortium Steering Committee Member, outside the submitted work. The remaining authors have no potential conflicts of interest to disclose.