Functional imaging of the airways

The use of traditional pulmonary function tests (PFT) to assess airflow obstruction is limited by the fact that these measurements are global and can neither express the potential regional heterogeneity nor localize the distribution of airways involved. High-resolution computed tomography (HRCT) is an established technique for the detailed evaluation of the pulmonary parenchyma. The development of helical scanning techniques enables volume datasets to be acquired through regions of interest in a single breathhold. Acquired during different phases of suspended respiration or under different physiologic conditions, these image sets provide potential insights into the relationships between airway structure and function. Volumetric data in also amenable to advance image processing algorithms enabling more precise characterization of bronchial morphology. This review considers the challenge of assessing cardiopulmonary function due to the complexity of the heart and lungs. The considerable insights that have been gained about airway physiology in animal experimentation are discussed. Studies investigating the role of volume acquisition's Helical CT and Electron Beam CT techniques of evaluating functional small airways function in humans are reviewed in detail and potential methods for analysis of airflow obstruction and detection of airway reactivity are extensively considered.