Lobe-based computed tomography assessment of airway diameter, airway or vessel number, and emphysema extent in relation to the clinical outcomes of COPD

Kazuyoshi Kurashima,1 Yotaro Takaku,1 Toshiko Hoshi,2 Tetsu Kanauchi,2 Keitaro Nakamoto,1 Noboru Takayanagi,1 Tsutomu Yanagisawa,1 Yutaka Sugita,1 Yoshinori Kawabata3 1Respiratory Medicine, 2Radiology, 3Pathology, Saitama Cardiovascular and Respiratory Center, Saitama, Japan Objective: The aim of this study was to evaluate the relationship between computed tomography assessed lobe-based lung parameters and the clinical outcomes of patients with chronic obstructive pulmonary disease (COPD), including the frequency of exacerbation and annual change in forced expiratory volume in 1 second (FEV1). Patients and methods: We studied 65 patients with COPD. We reconstructed computed tomography images to trace the bronchial tree from right B1 to B10 and created 3 cm circle images around the airways exactly perpendicular to the airway axis in the central, middle, and peripheral zones of the bronchi. The number of airways and vessels, airway inner diameter and area of emphysema in the circles were calculated for each segment. Then, we analyzed the relationships between the lobe-based image parameters and the frequency of exacerbation and annual decline in the FEV1. In addition, we assessed the effects of proximal airway lumen-obliterated emphysema (ALOE) on these clinical features. Results: The airway diameter was not associated with the frequency of exacerbation or annual decline in FEV1. Among the structural parameters, lower lobe emphysema was most associated with the frequency of exacerbation. The reductions in the number of airways and vessels in total lobe were associated with the annual decline in FEV1. The subgroup of patients with ALOE demonstrated lower FEV1 and more frequent exacerbation than those without ALOE. Conclusion: Lower lobe emphysema predicts frequent COPD exacerbation, whereas the annual decline in FEV1 is associated with the number of airways and vessels in total lobe. Keywords: chronic obstructive pulmonary disease, computed tomography, acute exacerbation, pulmonary function tests, low attenuation area&nbsp