Low-Attenuation Areas of the Lungs on High-Resolution Computed Tomography in Asthma

Abstract

To investigate the low-attenuation areas of the lungs (LAA) in asthma, we compared the mean lung density (MLD) and the LAA in 22 asthmatics (12 ex-smokers and 10 nonsmokers) and 13 patients with chronic obstructive pulmonary disease (COPD) by high-resolution computed tomography. The MLD and the relative area of the lung with attenuation values lower than −950 Hounsfield Units at full inspiration (inspiratory RA₉₅₀) were significantly different in nonsmoking asthmatics compared to patients with COPD and asthmatics with a smoking history. The MLD and the RA₉₅₀ correlated significantly with the FEV₁ in all groups and with the DL_CO in patients with COPD and asthmatics with a smoking history but not in nonsmoking asthmatics. We concluded that the LAA in asthmatics with a smoking history indicates the presence of emphysema, but in nonsmoking asthmatics it reflects hyperinflation and nonemphysematous expiratory airflow limitation rather than emphysematous lesions.

• Asthma
• DL_CO
• FEV₁
• High-resolution computed tomography
• Low-attenuation area