Measurement Of Lung Volumes From MSCT Images In Patients With Chronic Obstructive Pulmonary Disease

Objective To study the correlation of lung volumes measured with 64-slice CT (MSCT) and pulmonary function test (PFT) outcomes, and the value in diagnosing chronic obstructive pulmonary disease (COPD).Subjects and Methods In 46 cases, there were 22 healthy controls, 24 patients with chronic obstructive pulmonary disease (COPD). All cases were strictly selected except the diseases which impact the lung function ,such as thoracic deformity, a history of lung surgery, a large area of pulmonary infection, pleural effusion, pulmonary mass of which the diameter is longer than 4cm and so on . CT scan and PFT were performed within one week in all cases.The total lung was respectively scanned at full inspiration and full expiration with MSCT. The total lung volumes were measured by Pulmo pulmonary quantitative software.The pulmonary volume indices included full inspiratory volume (Vin ) , full expiratory volume (Vex ) , difference in lung volume (Vin-Vex ) , ratio in lung volume (Vex / Vin ) ,while the indices of PFT were total lung capacity ( TLC) , residual volume (RV) , RV/TLC , vital capacity (VC) , forced expiratory volume at the first second %pre ( FEV1% ) and ratio of the first second forced expiratory volume to forced vital capacity (FEV1/FVC%). The repeatability was tested by SPSS13.0 ,and the CT indexes were analyzed the correlation with PFT outcomes.Results Rank sum test was carried to assess the difference between the data from the two analysis of the same scan by the same operator : 23 cases were random selected , the difference of total capacity has no statistical significance,Vin(P=0.3294),Vex (P=0.2002)。Independent samples t-test was carried to assess the difference between the data from PFT outcomes . There were significant differences between the control group and the COPD group in the TLC,RV,RV/ TLC%,VC,FEV1%,FEV1/ FVC%( P < 0. 05).The major changes of COPD group in PFT :TLC and RV increase, in which the increase in RV was significantly higher than TLC, so RV/TLC% increases too; while VC decreased slightly, and FEV1 %, FEV1 / FVC% was significantly decline.The same situation happens in MSCT indexes .There were significant differences between the control group and the COPD group in the full expiration volume (Vex) , the full inspiration volume (Vin) , Vin-Vex and Vex/Vin ( P < 0. 05).In COPD group : Vin,Vex and Vex/Vin increase, in which the increase in Vex was significantly higher .There were significant differences between the the MSCT indexes and PFT outcomes by Rank sum test.Spearman correlation analysis was carried to assess the correlation of the indexes .Vin correlated with total lung capacity (TLC) (t = 0. 923 , P < 0. 05),and Vex well correlated with residual volume(RV) (t = 0. 912 , P < 0. 05), as well as Vin-Vex with vital capacity (VC) (t = 0.763,P <0.05),Vex/Vin with RV/TLC (t = 0. 754 , P < 0. 05). The Vex showed best correlation with FEV1% and FEV1 /FVC (t =-0.616,-0.543).Conclusion Significant correlated with PFT, MSCT pulmonary volumes indices can be used to evaluation the pulmonary function of patients with COPD.