Abstract
Background: Smoking causes inflammation in the lungs, which may lead to structural changes and irreversible airways obstruction, characteristic for COPD. By computered tomography (CT), areas with Hounsfield units (HU) below -950 have been considered as emphysema, while increased attenuation may indicate inflammation. We investigated changes in smokers compared to neversmokers.
Materials and methods: 40 current smokers (35±12 pack-years; mean ± SD) with normal lung function and 36 healthy neversmokers performed chest X-ray and CT. Age was 45-65 years with equal sex distribution. Lungs were defined as voxels with attenuation between -300 to -1024 HU, further divided into eight intervals. Chest X-rays were evaluated according to 4 criteria: depressed diaphragm, irregular radiolucency, abnormal retrosternal space and sternodiaphragmatic angle >90°. Two or more criteria's was considered as emphysema.
Results: Mean lung attenuation in male (-858HU±34; mean± SD) and female smokers (-856HU±19) was higher than in neversmokers (male -880HU±20; females- 872HU±18) (p<0.05 for both). In women, the percent of areas with HU below -950 was lower in smokers than neversmokers (p<0.001), the difference was smaller in men (p<0.05). Chest X-ray detected emphysema in 22% of male and 15% of female smokers, but in none of the neversmokers.
Discussion: Increased lung density in smokers may indicate inflammation but this has to be correlated to other signs of local inflammation. Females may be more vulnerable than males to the effects of smoking. Despite normal lung function, a considerable number of subjects had emphysema on plan chest x-ray. Further analyses are in progress including patients with COPD.
- © 2011 ERS
