Quantitative analyzes of the variability in airways via four-dimensional dynamic ventilation CT in patients with chronic obstructive pulmonary disease: correlation with spirometry data and severity of airflow limitation

Wei-Ting Hu; Wei Chen; Min Zhou; Jing Fan; Fuhua Yan; Bing Liu; Fang-Ying Lu; Rong Chen; Yi Guo; Wenjie Yang

doi:10.21037/jtd-23-573

Quantitative analyzes of the variability in airways via four-dimensional dynamic ventilation CT in patients with chronic obstructive pulmonary disease: correlation with spirometry data and severity of airflow limitation

J Thorac Dis. 2023 Sep 28;15(9):4775-4786. doi: 10.21037/jtd-23-573. Epub 2023 Aug 30.

Authors

Wei-Ting Hu^#^{1

2

3}, Wei Chen^#^{1

2

3}, Min Zhou^#^{1

2

3}, Jing Fan⁴, Fuhua Yan⁴, Bing Liu^{1

2

3}, Fang-Ying Lu^{1

2

3}, Rong Chen^{1

2

3}, Yi Guo^{1

2

3}, Wenjie Yang⁴

Affiliations

¹ Department of Pulmonary and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
² Institute of Respiratory Diseases, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
³ Shanghai Key Laboratory of Emergency Prevention, Diagnosis and Treatment of Respiratory Infectious Diseases, Shanghai, China.
⁴ Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

^# Contributed equally.

Abstract

Background: In chronic obstructive pulmonary disease (COPD) patients, the diagnosis and assessment of disease severity are mainly based on spirometry, which may lead to misjudgments due to poor patient compliance. Thoracic four-dimensional dynamic ventilation computed tomography (4D-CT) provides more airway data approximating true physiological function than conventional CT. We aimed to determine dynamic changes in airways to elucidate the pathological mechanism underlying COPD and predict the severity of airflow limitation in patients.

Methods: Forty-two COPD patients underwent 4D-CT and spirometry. The minimum lumen diameter changed with the breathing cycle in 4th-generation airways and was continuously measured in the apical (RB1), lateral (RB4) and posterior basal segments (RB10) of the right lung. The minimum lumen diameter in the peak inspiration and peak expiration as well as the peak expiratory/peak inspiratory ratio (E/I ratio), and dynamic coefficient of variance (CV) were calculated.

Results: Correlations of FEV₁% with the CV of minimum lumen diameter in RB1 (ρ=-0.473, P=0.002) and in RB10 (ρ=-0.480, P=0.005) were observed, suggesting that the dynamic variability in 4th-generation airways was associated with airflow limitation in COPD patients. The CV of the minimum lumen diameter in RB1 significantly differed between the GOLD I + II and GOLD III + IV groups {8.59 [interquartile range (IQR), 6.63-14.86] vs. 14.64 (10.65-25.88), respectively; P=0.016}, suggesting that the dynamic CV in RB1 increased significantly in the GOLD III + IV group, which had worse pulmonary ventilation function. Based on the receiver operating characteristic (ROC) curve analysis, CV-RB1 predicted FEV₁% <50% with an optimal cut-off of 9.43% [sensitivity 85.7%, specificity 57.1%, area under the curve (AUC) 0.717].

Conclusions: 4D-CT might be an available method to help diagnose and evaluate the severity of COPD.

Keywords: Chronic obstructive pulmonary disease (COPD); airflow limitation; four-dimensional dynamic ventilation computed tomography (4D-CT); quantitative CT.