Correlations of Computed Tomography Measurement of Distal Pulmonary Vascular Pruning with Airflow Limitation and Emphysema in COPD Patients

Guoyan Tang,1,&ast; Fengyan Wang,1,&ast; Zhenyu Liang,1,&ast; Cuixia Liang,2,&ast; Jinling Wang,3,&ast; Yuqiong Yang,1 Wanyi Tang,1,4 Weijuan Shi,1 Guoqiang Tang,3 Kai Yang,5 Zihui Wang,1 Qiasheng Li,1 Hualin Li,1 Jiaxuan Xu,1 Deyan Chen,2 Rongchang Chen5 1State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China; 2Neusoft Medical Systems Co., Ltd, Shenyang, People’s Republic of China; 3Qingyuan Chronic Disease Prevention Hospital, Qingyuan Occupational Disease Prevention Hospital, Qingyuan, People’s Republic of China; 4Qingyuan People’s Hospital, the Sixth Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China; 5Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Southern University of Science and Technology, Second Clinical Medical College of Jinan University, Shenzhen People’s Hospital, Shenzhen Institute of Respiratory Diseases, Shenzhen, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Rongchang Chen, Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Southern University of Science and Technology, Second Clinical Medical College of Jinan University, Shenzhen People’s Hospital, Shenzhen Institute of Respiratory Diseases, Shenzhen, People’s Republic of China, Email chenrc@vip.163.com Zhenyu Liang, State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China, Email 490458234@qq.comBackground: Pulmonary vascular alteration is an important feature of chronic obstructive pulmonary disease (COPD), which is characterized by distal pulmonary vascular pruning in angiography. We aimed to further investigate the clinical relevance of pulmonary vasculature in COPD patients using non-contrast computed tomography (CT).Methods: Seventy-one control subjects and 216 COPD patients completed the questionnaires, spirometry, and computed tomography (CT) scans within 1 month and were included in the study. Small pulmonary vessels represented by percentage of cross-sectional area of pulmonary vessels smaller than 5 mm2 or 5– 10 mm2 to the total lung fields (%CSA< 5 or %CSA5– 10, respectively) were measured using ImageJ software. Spearman correlation was used to investigate the relationship between %CSA< 5 and airflow limitation. A receiver operating characteristic (ROC) curve was built to evaluate the value of %CSA< 5 in discriminating COPD patients from healthy control subjects. Segmented regression was used to analyze the relationship between %CSA< 5 and %LAA-950 (percentage of low-attenuation areas less than − 950 HU).Results: We found a significant correlation between %CSA< 5 and forced expiratory volume in one second (FEV1) percentage of predicted value (%pred) (r = 0.564, P < 0.001). The area under the ROC curve for the value of %CSA< 5 in distinguishing COPD was 0.816, with a cut-off value of 0.537 (Youden index J, 0.501; sensitivity, 78.24%; specificity, 71.83%). Since the relationship between %CSA< 5 and %LAA-950 was not constant, performance of segmented regression was better than ordinary linear regression (adjusted R2, 0.474 vs 0.332, P < 0.001 and P < 0.001, respectively). As %CSA< 5 decreased, %LAA-950 slightly increased until an inflection point (%CSA< 5 = 0.524) was reached, after which the %LAA-950 increased apparently with a decrease in %CSA< 5.Conclusion: %CSA< 5 was significantly correlated with both airflow limitation and emphysema, and we identified an inflection point for the relationship between %CSA< 5 and %LAA-950.Keywords: computed tomography, pulmonary vascular pruning, airflow limitation, emphysema, chronic obstructive pulmonary disease