The benefit of expiratory-phase quantitative CT densitometry in the early diagnosis of chronic obstructive pulmonary disease.

Purpose: We aimed to compare the inspiratory and expiratory quantitative computed tomography (CT) densitometric data of healthy volunteers, individuals with chronic obstructive pulmonary disease (COPD) risk, and COPD patients to aid in the early diagnosis of COPD.
Materials and Methods: Of the study patients, 14 were healthy volunteers (Group I), 12 were patients at risk for COPD (Group II), and 13 were COPD patients (Group III). The high-resolution CT was performed at three levels (the upper, middle, and lower parts of the lungs). All images were evaluated with a specific program for the segmentation of pulmonary parenchyma. The mean lung density (MLD) was measured, and the emphysema index (EI) was calculated using this program.
Results: Both MLD values and calculated EI ratios showed significant differences between Groups I and III, and Groups II and III in both expiratory and inspiratory phases (P < 0.05). However, in the comparison of healthy volunteers and patients at risk for COPD (Group I and II), only expiratory-phase MLD values showed statistically significant difference (P < 0.001).
Conclusion: In patients at risk for COPD, expiratory-phase MLD measurements can be used as an early diagnostic method.