Three-dimensional airway lumen volumetry: Comparison with bronchial wall area and parenchymal densitometry in assessment of airway obstruction in pulmonary emphysema

Objectives: The purpose of this study was to compare three-dimensional airway lumen volumetry with bronchial wall area and parenchymal densitometry in the assessment of airway obstruction in pulmonary emphysema. Methods: 56 patients, who were smokers, underwent CT examination and pulmonary function tests (PFTs). For quantitative assessments, the following parameters were computationally calculated: (1) percentage of voxels 2950, 2960 and -970 HU in the lung (%LAA_-950, %LAA_-960 and %LAA_-970, respectively); (2) percentage of partial bronchi luminal volumes per total luminal volumes (LV_main, main and distal bronchial volume/total luminal volume; LV_lobe, lobar and distal bronchial volume/total luminal volume); and (3) mean wall area percentages of segmental bronchi of the right apical and left apicoposterior segment (WA%_seg) and of subsegmental bronchi (WA%_sub) in the upper lobes. These parameters were correlated with PFTs and statistically compared between a chronic obstructive pulmonary disease (COPD) group [forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC)<70] and a non-COPD group. Results: FEV1, maximum mid-expiratory flow rate and forced expiratory flow at 25% vital capacity had significant correlation with LV_main (r>0.53, p<0.0001), LV_lobe (r>0.52, p<0.0001), WA%seg (|r|>0.29, p<0.05) and WA%_sub (|r|>0.31, p<0.05). FEV1/FVC had significant correlation with all parameters (0.27,|r|<0.52, p<0.05). LV_main and LV_lobe and WA%_seg and WA% _sub were significantly different between the two groups (LV _main and LV_lobe; p<0.0001, WA%_seg and WA%_sub; p<0.05). Conclusions: Bronchial luminal volumetric assessment better reflected the airflow limitation parameters. Advances in knowledge: Bronchial luminal volumetric assessment can potentially be used to gauge airflow limitation in pulmonary emphysema.