1. Department of Ultrasound, The 2nd Affiliated Hospital of Harbin Medical University, Harbin 150081, Heilongjiang, China
2. Department of Ultrasound, The First Affiliated Hospital of Xiamen University, Xiamen 361003, Fujian, China
3. Department of Ultrasound, Xuanwu Hospital Capital University, Beijing 100053, China
4. Department of Gynecology and Obstetrics, The 2nd Affiliated Hospital of Harbin Medical University, Harbin 150081, Heilongjiang, China
5. Department of Ultrasound, Shenzhen University General Hospital, Shenzhen 518055, Guangdong, China