256 Slice CT Evaluation Of Morphologic And Functional Efects Of Smoking Lung

Objective To evaluate the morphology and function of smoking lung in asymptomatic adult subjects by using 256 slice CT.Methods 51 nonsmoking cases were divided into 3 groups: 20 to 39 years (n=14), 40 to 59 years (n=22), and over 60 years (n=15), and 65 smoking cases were divided into 3 groups: 20 to 39 years (n=17), 40 to 59 years (n=28), and over 60 years (n=20). All the subjects underwent thin-section slice plain CT scans at full inspiration and full expiration. The imaging would be watched with the window width 1500HU and the window level -400～-600 HU. The whole lung would be divided into six parts to watched: the upper lung field—upon the tracheal long axon level,the middle lung field—between the tracheal long axon level and the right inferior pulmonary vein level, and the lower lung field—below the right inferior pulmonary vein level. The evaluation indices included, emphysematous changes, micronodules, ground glass density shadow, interlobular septal thickening and air trapping. According to the relative score standard, the above mentioned indices were totally calculated and converted into the score value.One of the above CT signs appeared at one lung filed was one score. At last calculated the total score. The data were statistically processed with SPSS for Windows. Analysed the difference of the CT signs between the smoking group and the nonsmoking group in different age group, and the correlation between the total score and the smoking index. Besides that, all the imaging would be dealt with by the pulmonary emphysema quantitative software to calculate the volume ratio of the emphysema volume and the lung, and analysed the difference between the smoking group and the nonsmoking group in different age group. The imaging of 15 smoking cases and 20 nonsmoking cases who would underwent the clinical lung function testing in the same week would be dealt with by the pulmonary emphysema quantitative software to calculate the volume of full inspiration and full expiration. And then analysed the correlation between the CT lung volume indexes and clinical lung function indexes . Results Between the nonsmoking and smoking groups,there were no difference of the main CT signs, the total score and the emphysema quantitaty in the 20~39years(p>0.05), and there were remarkable differences of emphysematous changes, micronodules, interlobular septal thickening, the total score and the emphysema quantitaty in 40~59 years and over 60 years(p<0.05). The score values had a significant positive correlation with the smoking index (r=0.75, p<0.01). And the emphysema quantity had a positive correlation with the smoking index (r= 0.63, p <0.01) . Among the lung volumes from MSCT, Vin was in positive correlation with total lung capacity (TLC) (r=0.89, p <0.01) and Vex was also in positive correlation with residual volume (RV) (r=0.72, p<0.01) , as well as Vin - Vex with vital capacity (VC) (r=0.80, p <0.01) and Vex/Vin with RV/TLC (r=0.55, p<0.01) . Conclusion The CT imaging of the smoking lung was not obvious in the young people, but was obvious in the aged and elderly people, which become prominent as the smoking index. The main CT signs of smoking lung included emphysematous changes, micronodules, interlobular septal thickening, air trapping, ground glass density shadow.There were positive correlations between lung volume measured by MSCT and clinical lung function instrument. In brief, HRCT is one of the most important methods for evaluating the early signs of the smoking lung.