Utility of single-slice high-resolution CT in upper lung field combined with low-dose spiral CT for lung-cancer screening in the detection of emphysema.

OBJECT: The present study was undertaken to evaluate the utility of low-dose spiral CT scanning, combined with single-slice high-resolution CT (HRCT), in the detection of pulmonary emphysema on CT (CTPE) together with screening for lung cancer. SUBJECTS AND METHODS: For 657 individuals who visited for screening of lung cancer, single-slice HRCT of the upper lung field was added on conventional low-dose spiral CT scanning in order to detect low attenuation area (LAA) visually. The individuals were classified into four groups according to the visual extent of LAA in bilateral upper lung fields: no LAA, subtle PE (0%<LAA%< or =5%), mild PE (5%<LAA%< or =25%) and moderate to severe PE (LAA%>25%), and compared spirometry among the four groups.
RESULTS: LAA was detected in 23.3% of all subjects (subtle PE in 12.2%, mild PE in 9.9% and moderate to severe PE in 1.2%) by adding one HRCT slice whereas only in 6.4 % LAA was detected by conventional low-dose helical CT scanning at 10 mm slice alone. The airway obstruction (FEV1/FVC<70%) was observed only in 1.07%. The severity of emphysema was associated with older age, prevalence of having smoking history and Brinkman index. As the severity of emphysema, the FEV1/FVC, MMEF, and V25/HT showed lower values.
CONCLUSIONS: It is suggested that single-slice HRCT of the upper lung field combined with conventional low-dose spiral CT scanning for screening of lung cancer may also be useful for the detection of LAA, which may promote smoking cessation.