1. Department of Ultrasonography, First People's Hospital of Linping District, Hangzhou, Zhejiang 311100, P.R. China
2. Department of Special Inspection, The Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310005, P.R. China
3. Department of Ultrasonography, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, P.R. China