1. Department of Ultrasound, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
2. Gastroenterological Center, Yokohama City University Medical Center, Yokohama, Kanagawa, Japan.
3. Department of Pathology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
4. Division of Gastroenterology, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan.