1. Department of Ultrasound, Yantaishan Hospital, Yantai, Shandong 264000, P.R. China
2. Department of Ultrasound, Yantai Hospital of Traditional Chinese Medicine, Yantai, Shandong 264000, P.R. China
3. Department of Clinical Laboratory, Yantaishan Hospital, Yantai, Shandong 264000, P.R. China
4. Department of Ultrasound, Shandong Medical Imaging Research Institute, Jinan, Shandong 250021, P.R. China