Emphysema Quantification using Low Dose Chest CT : Efficacy of Follow up Examinations in Asymptomatic Smokers

Pulmonary function test (PFT), plain chest radiography and computed tomography(CT) of chest are commonly used for the diagnosis of emphysema. It is important to diagnose emphysema. However, it is more important to evaluate the degree of extent and progression of emphysema, because they are related to the choice of treatment between convervative and surgical treatment. Most of the previous studies with low dose CT reported their results of emphysema quantification, compared with the standard dose CT or compared with PFT without follow up low dose CT. According to my knowledge, there is no report about the performance of low dose CT to evaluate emphysema progression by comparison between PFT and emphysema quantification of initial and follow up low dose CT. The purpose of this study is to evaluate whether emphysema progression can be predicted by emphysema quantification of low dose chest CT in asymptomatic smoker. From January, 2010 to April, 2011, 66 asymptomatic smokers with age greater than 40 years and who had initial low dose CT and at least one year follow up low dose CTs were retrospectively selected. In all the patients, follow up low dose CT was performed with the same protocol as the initial low dose CT images. Emphysema quantification was performed by using workstation with the automated measurement software. To detect the emphysema, threshold values (-970HU ~ -900HU) were selected with 10HU interval. In each threshold, emphysema index, which was defined as the percentage of low attenuated areas and total lung volume, was calculated by using software. To evaluate the emphysema progression, the change of emphysema index in low dose CT was calculated and to investigate the performance, it was also compared with the change of PFT. Compared with the initial PFT parameters, follow up FEV1, FVC and FEF25%-75% were significantly decreased(p<0.001, p=0.005, p<0.001). In all thresholds, the emphysema indeces were increased but it was not statistically significant. In the initial and low dose CTs of over two year follow up smokers, in the setting of -900HU as threshold, the last emphysema indeces were significantly increased(p=0.02). Compared with the changes in the parameter of PFT, the changes of emphysema indeces in all thresholds demonstrated weak negative correlation with ΔFEV1 but it was not statistically significant (r=-0.170～-0.007, p>0.05). The changes of emphysema indeces in -940HU～-900HU demonstrated weak negative correlation with ΔFVC with statistical significance (r=-0.260～0.320, p<0.05). According to the results of this study, it is possible to predict emphysema progression in low dose CT by using emphysema quantification. But the limitations of the results are the weak correlation with PFT and no proven data with statistical significance. More studies are required for using emphysema quantification to evaluate emphysema progression.

Author dc:creator

• 장, 은호

Contributors dc:contributor

• 박, 경주
• 대학원 의학과
• 200924592

• 폐기종
• 정량화
• 저선량 CT
• 폐기능 검사
• Emphysema
• Low Dose Chest CT
• Quantification

Language dc:language

ko

Identifier

http://dcoll.ajou.ac.kr:9080/dcollection/jsp/common/DcLoOrgPer.jsp?sItemId=000000011930
000000011930

OAI identifier oai:identifier

oai:repository.ajou.ac.kr:201003/4419