[1] Sichuan Univ, West China Univ Hosp 2, Dept Ultrasound, 20,Sect 3 Renmin South Rd, Chengdu 610041, Sichuan, Peoples R China
[2] North Sichuan Med Coll, Nanchong Cent Hosp, Clin Med Coll 2, Dept Ultrasound, Nanchong, Sichuan, Peoples R China
[3] Sichuan Univ, Key Lab Birth Defects & Related Dis Women & Childr, Minist Educ, Chengdu, Sichuan, Peoples R China
[4] Beijing Key Lab Maternal Fetus Med Fetal Heart Dis, Beijing, Peoples R China
[5] Capital Med Univ, Beijing Anzhen Hosp, Echocardiog Med Ctr, Beijing, Peoples R China