Air Trapping in Sarcoidosis on Computed Tomography: Correlation with Lung Function

Abstract

AIMS: To document the presence and extent of air trapping on high resolution computed tomography (HRCT) in patients with pulmonary sarcoidosis and correlate HRCT features with pulmonary function tests.METHODS: Twenty-one patients with pulmonary sarcoidosis underwent HRCT and pulmonary function assessment at presentation. Inspiratory and expiratory HRCT were assessed for the presence and extent of air trapping, ground-glass opacification, nodularity, septal thickening, bronchiectasis and parenchymal distortion. HRCT features were correlated with pulmonary function tests.RESULTS: Air trapping on expiratory HRCT was present in 20/21 (95%) patients. The extent of air trapping correlated with percentage predicted residual volume (RV)/total lung capacity (TLC) (r=0.499;P<0.05) and percentage predicted maximal mid-expiratory flow rate between 25 and 75% of the vital capacity (r=−0.54;P<0.05). Ground-glass opacification was present in four of 21 (19%), nodularity in 18/21 (86%), septal thickening in 18/21 (86%), traction bronchiectasis in 14/21 (67%) and distortion in 12/21 (57%) of patients; there were no significant relationships between these CT features and pulmonary function results.CONCLUSION: Air trapping is a common feature in sarcoidosis and correlates with evidence of small airways disease on pulmonary function testing.Davies, C. W. H. (2000). Clinical Radiology55, 217–221.