Normal range of emphysema and air trapping on CT in young men.

OBJECTIVE. The purpose of our study was to assess the normal range of CT measures of emphysema and air trapping in young men with normal lung function. MATERIALS AND METHODS. A cohort of 70 young men with high-normal spirometry and body plethysmography underwent paired inspiratory and expiratory CT. Visual and quantitative scores of emphysema and air trapping were obtained. On CT, emphysema was defined as the 15th percentile of the attenuation curve (Perc15), and as the percentage of inspiratory voxels below –950 (IN–950) and below –960 (IN–960) HU. On CT, air trapping was defined as the expiratory-to-inspiratory ratio of mean lung density (EI-ratioMLD), and the percentage of voxels below –856 HU in expiration (EXP–856). Means, medians, and upper limits of normal (ULN) are presented for the total population and for smokers and nonsmokers separately. RESULTS. The mean age (± SD) of the subjects was 36.1 ± 9.3 years. Smoking history was limited (range, 0–11 pack-years). Spirometry was high normal, ranging f...