[1] Seoul Natl Univ, Coll Med, Div Pulm & Crit Care Med, Seoul, South Korea
[2] Seoul Natl Univ, Coll Med, Dept Internal Med, Lung Inst, Seoul 151, South Korea
[3] Seoul Natl Univ, Dept Internal Med, Div Pulm & Crit Care Med, Boramae Med Ctr, Seoul, South Korea
[4] Seoul Natl Univ, Coll Med, Dept Radiol, Seoul, South Korea
[5] Konkuk Univ Hosp, Dept Resp Med, Seoul, South Korea
[6] Natl Canc Ctr, Ctr Lung Canc, Goyang, Gyeonggi Do, South Korea
[7] Inha Univ, Sch Med, Dept Social & Prevent Med, Inchon, South Korea