Objective To investigate the impact of spatial distribution of emphysema on pulmonary function and clinical severity in patients with chronic obstructive pulmonary disease (COPD).Methods Chest MSCT was performed in 84 patients with COPD.The percentage of low attenuation areas were automatically calculated for each lobe with the COPD analysis software.The correlations between low-attenuation area percent(LAA％) of each lobe and the parameters of pulmonary function were analyzed.According to the pulmonary emphysema heterogeneity index,the patients were divided into non-emphysema group and emphysema group,and the latter were divided into the predominantly upper lobe subgroup and the predominantly lower-lobe subgroup.The differences of pulmonary function parameters between the 2 groups and clinical severity between the 2 subgroups in emphysema group were compared.Results LAA％ of each lobe was negatively correlated with single breath carbon monoxide diffusing capacity to predicted value ratio (DLcoSB％pred).Except for the right middle lobe,LAA％ of the remaining lobes were negatively correlated with forced expiratory volume in one second/forced vital capacity (FEV1/FVC) and FEV1％pred,while positively correlated with resonance frequency (Fres).The differences of pulmonary function parameters between the 2 groups were statistically significant (all P ＜ 0.05).The differences of FEV1％pred and FEV1/FVC between the 2 subgroups in emphysema group were statistically significant (all P ＜0.05),and the differences of Fres and DLcoSB％pred between the 2 subgroups were not statistically significant (all P＞0.05).The difference of clinical severity between the 2 subgroups was statistically significant (x2 =4.17,P=0.041).Conclusion The spatial distribution of pulmonary emphysema affects pulmonary function and clinical severity in COPD patients.The patients with the predominantly lower-lobe emphysema are relatively worse in lung function,and more serious in the clinical severity.