1. Department of Ultrasound, Chengdu First People's Hospital, Chengdu, Sichuan 610041, P.R. China
2. Department of Pathology, West China Hospital, Sichuan University, Chengdu, Sichuan 610065, P.R. China
3. Department of Pathology, Chengdu First People's Hospital, Chengdu, Sichuan 610041, P.R. China