[Pulmonary structure and function]

Computed tomography (CT) is the method of choice for the morphological assessment of pulmonary structure. Airways. pulmonary parenchyma and their pathologies are shown with high spatial resolution. Airway diseases exhibit bronchial dilatation, wall thickening and an increased visibility in the lung periphery. CT is also the imaging gold standard for the detection and the characterisation of emphysema because a high degree of concordance with histopathological studies. Centrilobular, panlobular and paraseptal emphysema can be differentiated. CT can also provide functional information. Paired inspiratory and expiratory scans with or without spirometric triggering allow to evaluate obstruction of the small airways (airtrapping). On the basis of CT-data lung volumes can be semented. Cine-CT allows to visualise motion of the central airways. e.g. in tracheomalacia, to assess regional ventilation to calculate pulmonary time constants. and to display the co-ordinated or dissociated motion of the thoracic wall and the diaphragm. Beyond the mere high-resolution visualisation of the structure of the lung the application of these CT-strategies makes a regional assessment of pulmonary function possible.