1. Department of Ultrasound, Beijing Obstetrics and Gynecology Hospital; Capital Medical University; Beijing P.R. China
2. BioChain (Beijing) Science & Technology Inc.; Beijing P.R. China
3. Department of Obstetrics, Beijing Obstetrics and Gynecology Hospital; Capital Medical University; Beijing P.R. China
4. Department of Ultrasound; Chinese PLA General Hospital (No. 301 Hospital); Beijing P.R. China