To evaluate the relationship between measurements of lung volume (LV) on inspiratory/expiratory
computed tomography (CT) scans, pulmonary function tests (PFT), and CT measurements
of emphysema in individuals with chronic obstructive pulmonary disease.
Forty-six smokers (20 females and 26 males; age range 46-81 years), enrolled in the
Lung Tissue Research Consortium, underwent PFT and chest CT at full inspiration and
expiration. Inspiratory and expiratory LV values were automatically measured by open-source
software, and the expiratory/inspiratory (E/I) ratio of LV was calculated. Mean lung
density (MLD) and low attenuation area percent (<-950 HU) were also measured. Correlations
of LV measurements with lung function and other CT indices were evaluated by the Spearman
rank correlation test.
LV E/I ratio significantly correlated with the following: the percentage of predicted
value of forced expiratory volume in the first second (FEV(1)), the ratio of FEV(1)
to forced vital capacity (FVC), and the ratio of residual volume (RV) to total lung
capacity (TLC) (FEV(1)%P, R = -0.56, P < .0001; FEV(1)/FVC, r = -0.59, P < .0001;
RV/TLC, r = 0.57, P < .0001, respectively). A higher correlation coefficient was observed
between expiratory LV and expiratory MLD (r = -0.73, P < .0001) than between inspiratory
LV and inspiratory MLD (r = -0.46, P < .01). LV E/I ratio showed a very strong correlation
to MLD E/I ratio (r = 0.95, P < .0001).
LV E/I ratio can be considered to be equivalent to MLD E/I ratio and to reflect airflow
limitation and air-trapping. Higher collapsibility of lung volume, observed by inspiratory/expiratory
CT, indicates less severe conditions in chronic obstructive pulmonary disease.
Copyright 2010 AUR. Published by Elsevier Inc. All rights reserved.