1. Peking University First Hospital Ningxia Women and Children’s Hospital, (Ningxia Hui Autonomous Region Maternal and Child Health Hospital), Ningxia 750001, P. R. China
2. Academy for Engineering and Technology, Fudan University Shanghai 200032, P. R. China
3. Academy for Engineering and Technology, Fudan University Shanghai Key Laboratory of Medical Image, Computing and Computer Assisted Intervention, Shanghai 200032, P. R. China