Aerodynamic Simulation of Small Airway Resistance: A New Imaging Biomarker for Chronic Obstructive Pulmonary Disease

To develop a novel method for calculating small airway resistance using computational fluid dynamics (CFD) based on CT data and evaluate its value to identify COPD.

24 subjects who underwent chest CT scans and pulmonary function tests between August 2020 and December 2020 were enrolled retrospectively. Subjects were divided into three groups: normal (10), high-risk (6), and COPD (8). The airway from the trachea down to the sixth generation of bronchioles was reconstructed by a 3D slicer. The small airway resistance (R_SA) and R_SA as a percentage of total airway resistance (R_SA%) were calculated by CFD combined with airway resistance and FEV₁ measured by pulmonary function test. A correlation analysis was conducted between R_SA and pulmonary function parameters, including FEV₁/FVC, FEV₁% predicted, MEF50% predicted, MEF75% predicted and MMEF75/25% predicted.

The R_SA and R_SA% were significantly different among the three groups (p<0.05) and related to FEV₁/FVC (r = -0.70, p < 0.001; r = -0.67, p < 0.001), FEV₁% predicted (r = -0.60, p = 0.002; r = -0.57, p = 0.004), MEF50% predicted (r = -0.64, p = 0.001; r = -0.64, p = 0.001), MEF75% predicted (r = -0.71, p < 0.001; r = -0.60, p = 0.002) and MMEF 75/25% predicted (r = -0.64, p = 0.001; r = -0.64, p = 0.001).

Airway CFD is a valuable method for estimating the small airway resistance, where the derived R_SA will aid in the early diagnosis of COPD.