1. Department of Ultrasound, Dalian Woman and Child Medical Center (Group), No. 1 Dunhuang Road, Shahekou District, Dalian, Liaoning 116030, China
2. Department of Radiology, Dalian Woman and Child Medical Center (Group), No. 1 Dunhuang Road, Shahekou District, Dalian, Liaoning 116030, China
3. Department of Fetal Medicine Center, Dalian Woman and Child Medical Center (Group), No. 1 Dunhuang Road, Shahekou District, Dalian, Liaoning 116030, China