[1] Univ Ulsan, Asan Med Ctr, Coll Med, Dept Internal Med, Seoul, South Korea
[2] Univ Ulsan, Asan Med Ctr, Coll Med, Dept Pulm & Crit Care Med, 388-1 Poongnab 2-Dong, Seoul, South Korea
[3] Univ Ulsan, Asan Med Ctr, Coll Med, Dept Radiol, Seoul, South Korea
[4] Univ Ulsan, Asan Med Ctr, Coll Med, Res Inst Radiol, Seoul, South Korea