Background: Endobronchial ultrasound (EBUS) is a new technique that enables the assessment of bronchial wall layers. The aim of the study was to verify the utility of EBUS for the assessment of bronchial wall remodeling in patients with asthma.
Methods: In 35 patients with asthma and 23 control subjects, high-resolution CT (HRCT) scanning and EBUS were used to measure bronchial wall thickness in the 10th segment of the right lung. With a radial 20-MHz probe, EBUS identified the 5-laminar structure of the bronchial wall. Layer 1 (L(1)) and layer 2 (L(2)) were analyzed separately, and layers 3 through 5 (L(3-5)), which corresponded to cartilage, were analyzed jointly. Digitalized EBUS images were used for the quantitative assessment of bronchial wall thickness and the wall area (WA) of the layers. Finally, bronchial biopsy specimens were taken for measuring the thickness of the reticular basement membrane (RBM). The thickness and WA of the bronchial wall layers, which were assessed using EBUS, were correlated with FEV(1) and RBM.
Results: There was no significant difference in the measurements of total bronchial wall thickness using EBUS and HRCT scanning. The thickness and WA of the bronchial wall and its layers were significantly greater in patients with asthma than in the control subjects. A negative correlation among the thicknesses of L(1), L(2), and L(3-5) and FEV(1), and a positive correlation with RBM were observed only in the patients with asthma.
Conclusions: EBUS allows precise measurement of the thickness and WA of bronchial wall layers. The correlation of these parameters with asthma severity suggests implementation of EBUS in the assessment of bronchial wall remodeling in patients with asthma.