Background. Asthma is a chronic inflammatory disorder of the airways characterized by airflow limitation and airway hyperresponsiveness. Lung density indices on quantitative computed tomography (QCT) are assumed to reflect the degree of air trapping originated from airflow limitation in airway diseases. Purpose. The present study investigated the availability of lung density indices on QCT in clinical evaluation of asthma. Methods. Eleven asthmatic patients and 48 healthy control subjects were prospectively evaluated by QCT, pulmonary function testing, and a methacholine challenge test. High-resolution computed tomography scans were performed at full-inspiratory and full-expiratory phases, and percentage of lung field occupied by low attenuation area (LAA%) and mean lung density (MLD) at both inspiratory and expiratory phases were measured. Results. MLD values at inspiratory phase were significantly increased in asthmatic patients compared with those in healthy control subjects. Inspiratory LAA% values were significantly decreased in asthmatics compared with the values in control subjects. On expiratory scans, MLD values of asthmatics were significantly lower than the values of control subjects. Expiratory LAA% values of asthmatics were significantly higher than the values of control subjects. The LAA% in the expiratory phase showed significant negative correlation with forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity, and the provocative dose of methacholine causing a 20% decrease in FEV1 in asthmatic patients. Conclusion. These results suggest that lung density indices on QCT may be useful for clinical evaluation of asthmatic patients and increased LAA% in the expiratory phase is associated with airflow limitation and airway hyperresponsiveness in asthma.
Bibliographical noteFunding Information:
ACKNOWLEDGMENT The authors thank professor Mie-Jae Im for careful reading of the manuscript. This work was supported by a grant of the Korea Science and Engineering Foundation (KOSEF) through the National Research Lab. Program funded by the Ministry of Education, Science and Technology R0A-2005-000-10052–0 ) and by a grant of the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare and Family Affairs, Republic of Korea (A040153).
Program funded by the Ministry of Science and Technology (R0A-2005-000-10052-0), by Korea Research Foundation Grant funded by Korea Government (MOEHRD, Basic Research Promotion Fund) (KRF-2005-201-E00014), by a grant of the Korea Health 21 R&D project, Ministry of Health & Welfare, Republic of Korea (A060169) (to Y. C. L.), and also by a grant from the Korea Health 21 R&D Project (0412-CR03-0704-0001) (to S. J. P.).
- Airflow limitation
- Airway hyperresponsiveness
- Computed tomography
- Lung density
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Immunology and Allergy
- Pulmonary and Respiratory Medicine