[1] Jeju Natl Univ, Sch Med, Jeju Natl Univ Hosp, Dept Internal Med, Jeju, South Korea
[2] Clin Res Ctr Chron Obstruct Airway Dis, Seoul, South Korea
[3] Hallym Univ, Kangdong Sacred Heart Hosp, Dept Pulm & Crit Care Med, 445 Gil Dong, Seoul 134701, South Korea
[4] Yonsei Univ, Coll Med, Dept Internal Med, Div Pulmonol, Seoul, South Korea
[5] Univ Ulsan, Asan Med Ctr, Coll Med, Dept Pulm & Crit Care Med, Seoul, South Korea
[6] Catholic Univ Korea, Seoul St Marys Hosp, Coll Med, Dept Internal Med, Seoul, South Korea
[7] Ewha Womans Univ, Seoul Hosp, Coll Med, Dept Internal Med, Seoul, South Korea
[8] CHA Univ, CHA Bundang Med Ctr, Dept Internal Med, Seongnam, South Korea
[9] Hanyang Univ, Guri Hosp, Coll Med, Dept Internal Med,Div Pulmonol, Guri, South Korea
[10] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Sch Med, Dept Med,Div Pulm & Crit Care Med, Seoul, South Korea
[11] Konkuk Univ, Sch Med, Dept Internal Med, Seoul, South Korea
[12] Univ Ulsan, Asan Med Ctr, Coll Med, Dept Radiol, Seoul, South Korea
[13] Univ Ulsan, Asan Med Ctr, Res Inst Radiol, Seoul, South Korea