Abstract: ［Abstract］〓Objective〖HTSS〗〓To analyze the relationship between percentages of low attenuation volume（LAV%） and pulmonary function test（PFT）， and to explore the diagnostic value of LAV%  in the quantitative emphysema assessment by using  computed tomography(CT) and the 3D Synapse software.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Thirtyone patients with emphysematype chronic obstructive pulmonary disease underwent CT examinations with a 64detectorrow CT scanner and pulmonary function tests. For the quantitative assessment, LAV% of whole lung, right lung, left lung, and each lobe were obtained using the 3D Synapse software. The relationship of LAV% and PFT parameters was analyzed. Then all the patients were divided into two groups on the basis of LAV%=15% ，which were the mild emphysema group(n=23) and the severe(n=8), LAV% in whole lung, right lung, left lung, and each lobe between the two group was compared.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The LAV% of both lower lobes, left lung and whole lung were weakly, negatively correlated to airflow limitation parameter(ratio of FEV1  to forced vital capacity)(P＜005). LAV% of right lung, left lung, both upper lobes and whole lung showed highly negative correlations with diffusing capacity(P＜005), and LAV% of right middle and both lower lobes were moderate negative correlations with diffusing capacity(P＜005) . The LAV% of whole lung, right lung, left lung, and each lobe in patients with severe emphysematype COPD group  was larger than in mild emphysematype COPD group(P＜005).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓LAV% of the emphysematype COPD  was  correlated to pulmonary function test. The change of pulmonary function test can be reflected effectively by the LAV%.

Key words: pulmonary disease, chronic obstructive, pulmonary emphysema, tomography, Xray computed