Airway Dimensions in Asthma and COPD in High Resolution Computed Tomography: Can We See the Difference?

Abstract

BACKGROUND: Airway remodeling in asthma and COPD results in bronchial wall thickening. The thickness of the bronchial wall can be measured in high-resolution computed tomography. The objectives of the study were to assess the bronchial lumen and wall dimensions in asthma and COPD patients, in relation to disease severity, and to compare the airway dimensions in patients with asthma and COPD. METHODS: Ten asthma subjects and 12 COPD subjects with stable, mild to moderate disease were investigated. All subjects underwent chest high-resolution computed tomography (window level ؊ 450 Hounsfield units, window width 1,500 Hounsfield units). Cross-sections of bronchi (external diameter 1.0 -5.0 mm) were identified on enlarged images. The following variables were measured: external and internal diameter, wall area, lumen area, total airway area, the percentage of airway wall area, wall thickness, and the ratio of wall thickness to external diameter. Separate sub-analyses were performed for airways with external diameter < 2.0 mm and external diameter > 2.0 mm. RESULTS: We measured 261 and 348 cross-sections of small airways in subjects with asthma and COPD, respectively. There was a significant difference in wall thickness and wall area, which were both greater in asthmatics than in COPD patients. In bronchi with external diameter > 2.0 mm, all measured parameters were significantly higher in asthma than COPD. In individual asthmatics the airway wall thickness was similar in all the assessed bronchi, while in COPD it was related to the external airway diameter. CONCLUSIONS: Our results indicate that bronchial walls are thicker in asthmatics than in patients with COPD. It seems that airway wall thickness and the lumen diameter in patients with asthma are related to disease severity. There is no such a relationship in COPD patients. High-resolution computed tomography may be a useful tool in the assessment of airway structure in obstructive lung disease.

Quantitative Low-Dose Computed Tomography of the Lung Parenchyma and Airways for the Differentiation between Chronic Obstructive Pulmonary Disease and Asthma Patients

“…However, there was no statistically significant difference in airway remodeling between the COPD and the control groups, indicating that there was no obvious airway remodeling in COPD. Similarly, we found that the asthma group had lower WA(WV)/BSA, LA(LV)/BSA, and TA(total volume)/ BSA, but higher WA%/WV% and Pi10WA than the COPD group, confirming findings by other investigators [27] that the airways of asthma patients tend to have smaller inner radii than those found in COPD patients [28][29][30] . Pathophysiological analysis confirmed that the airways of asthma patients have thicker basement membrane [31] and larger numbers of blood vessels [25] than COPD patients.…”

Airflow obstruction: is it asthma or is it COPD?

“…COPD patients have more prominent HRCT findings, such as parenchymal abnormalities, compared with asthmatics, whereas walls are thicker in asthmatics than in patients with COPD 39,40. In the asthmatics, abnormal HRCT findings are more prominent, with increased severity 41.…”

“…In the asthmatics, abnormal HRCT findings are more prominent, with increased severity 41. Actually, it seems that airway-wall thickness and lumen diameter are related to disease severity, decreased FEV 1 values, and duration of asthma 39,41. There is no such relationship in COPD patients 39.…”

“…Actually, it seems that airway-wall thickness and lumen diameter are related to disease severity, decreased FEV 1 values, and duration of asthma 39,41. There is no such relationship in COPD patients 39. The pattern of radiographic change from whole-lung HRCT differs between neutrophilic asthma and COPD 40.…”

Seeking for the links between biochemical markers of remodeling and structural changes in chronic obstructive pulmonary disease: where are we?

“…HRCT is also useful in the assessment of bronchial wall thickness (BWT). 6 In the last few years, several studies have shown that a new bronchoscopic technique, namely, endobronchial ultrasound (EBUS), may be used for the evaluation of airway remodeling in obstructive lung diseases. [7][8][9] Of note, there is a significant contribution of a research group from Cracow, Poland, to the development of the method and to the promotion of its application in respiratory research.…”