1. Department of Ultrasonography, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, P.R. China
2. Laboratory Center, Jinshan Hospital of Fudan University, Shanghai 201508, P.R. China
3. Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong 999077, SAR, P.R. China