ObjectiveTo explore the clinical significance of quantitative CT measurement of pulmonary vascular indexes in chronic obstructive pulmonary disease (COPD). MethodsFifty-three stable COPD patients who were diagnosed in our hospital between May 2013 and February 2015 were recruited in the study. The HRCT results were analyzed, and the pulmonary vascular indexes were measured including the main pulmonary artery diameter (mPAD), axial diagonal mPAD, sagittal mPAD, right pulmonary artery diameter (RPAD), left pulmonary artery diameter (LPAD) and etc. The % CSA<5 (the percent of total cross-sectional area of the vascular with cross-sectional area less than 5 mm2 to total area of the lung) was calculated with Image J 1.48. The % LAA[volume percentage of low attenuation areas (<-950 HU)] representing degree of emphysema was calculated with GE ADW 4.5. Lung function test and questionnaires including CAT, mMRC, SGRQ and frequency of acute exacerbation of COPD (AECOPD) were completed and collected. ResultsIn COPD patients, the mPAD,axial diagonal mPAD, sagittal mPAD, RPAD and LPAD were positively correlated with % LAA respectively (r=0.36, 0.33, 0.43, 0.45, 0.33) and % CSA<5 was negatively correlated with % LAA (r=-0.37). mPAD was positively correlated with CAT, SGRQ and frequency of AECOPD respectively (r=0.52, 0.29, 0.35), and negatively correlated with FEV1% pred (r=-0.30).% CSA<5 was negatively correlated with CAT, SGRQ and frequency of AECOPD, respectively (r=-0.29,-0.30,-0.29), and positively correlated with FEV1% pred (r=0.28). The multivariate linear regression analysis revealed a linear relationship of mPAD with body mass index,% LAA and CAT. There was also linear relationships between axial diagonal mPAD, sagittal mPAD, RPAD and % LAA, CAT, respectively, and linear relationships between % CSA<5 and FEV1% pred,% LAA. The P value were all less than 0.05. ConclusionQuantitative CT measurement of cross-sectional area of small pulmonary vessels and pulmonary artery diameter are associated with clinical indexes in COPD patients, which will provide a new appraoche for the disease assessment of COPD patients.