1. Department of Ultrasonography, Qianfoshan Hospital Affiliated to Shandong First Medical University, Jinan, China;
2. Department of Oncology, Liaocheng Tumor Hospital, Liaocheng, China;
3. Department of Gynecology, Weihai Municipal Hospital, Weihai, China;
4. Department of Ultrasonography, Liaocheng Tumor Hospital, Liaocheng, China