[1] Sichuan Univ, West China Hosp, West China Sch Med, Dept Resp & Crit Care Med,Div Pulm Dis,State Key L, Chengdu, Sichuan, Peoples R China
[2] Univ Elect Sci & Technol China, Chengdu Womens & Childrens Cent Hosp, Sch Med, Chengdu, Sichuan, Peoples R China
[3] Univ Elect Sci & Technol China, Chengdu Womens & Childrens Cent Hosp, Sch Med, Dept Ultrasound, Chengdu 610091, Sichuan, Peoples R China
[4] Sichuan Univ, West China Hosp, West China Sch Med, Dept Resp & Crit Care Med,Div Pulm Dis,State Key L, Chengdu 610041, Sichuan, Peoples R China