Functional imaging of airway distensibility

The physiological function of the respiratory system is essential in distending airway smooth muscle and maintaining airway patency. Deep inspirations can reverse contracted airways and protect airways from subsequent bronchospastic stimuli. Obstructive lung diseases may lead to impairment of the beneficial effects of lung inflation through either change in the airway wall or lung parenchyma. Conventional pulmonary function measurements are unable to assess airway stiffness, based on changes in airway size with lung inflation (distensibility). However, high-resolution computed tomography (HRCT) is unique in that it can be used to measure airway distensibility in animals and in humans. Functional imaging of airway distensibility can contribute to a better understanding of the mechanisms of action of deep inspirations and, consequently, to the understanding of the disease processes in asthma and COPD. Future studies could explore the role of functional imaging in the monitoring of the severity of the disease and the response to treatment.