[1] Fukushima Med Univ, Sch Med, Dept Pulm Med, Fukushima 9601295, Japan
[2] Ohara Gen Hosp, Dept Radiol, Fukushima 9608611, Japan
[3] Hokkaido Univ, Sch Med, Dept Med 1, Sapporo, Hokkaido 0608638, Japan
[4] Gifu Prefectural Gifu Hosp, Dept Resp Med, Gifu 5008717, Japan