ASSESSMENT OF AIR TRAPPING USING POSTEXPIRATORY HIGH-RESOLUTION COMPUTED-TOMOGRAPHY

The authors assess the utility of postexpiratory high-resolution compu ted tomography (HRCT) scans in the evaluation of air trapping in patie nts with obstructive lung disease. Thirteen healthy volunteers and 14 patients with obstructive lung disease (OLD) were examined using inspi ratory and postexpiratory HRCT scans. All had pulmonary function tests . Lung attenuation was measured on both inspiration and expiration, an d the extent of air trapping on postexpiratory scans was visually asse ssed. The results of the healthy volunteers were compared with those o f patients with OLD, and HRCT findings were correlated with pulmonary function tests. Lung attenuation on expiration, its change from inspir ation to expiration, and air-trapping scores of patients with OLD were significantly different from those of the healthy volunteers. When th e healthy participants and patients with OLD were combined and analyze d as one group, the lung attenuation change and air-trapping score bot h significantly correlated with pulmonary function tests (p < 0.001) a nd correlation values were similar (r = 0.61-0.89). Air trapping was f ound in 61% of healthy participants and all the patients with OLD, alt hough the extent was significantly greater in the patients with OLD. I nspiratory and postexpiratory HRCT can be used to evaluate air trappin g in patients with OLD. Measurements of lung attenuation and estimates of air-trapping extent are both valuable methods of analysis.