Jianjun Du1, Jianbo Shuang2, Jing Li3, Jipeng Li2, Jin Hua2. 1. Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xian, China; Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China. Electronic address: dujjp@hotmail.com. 2. Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xian, China. 3. Medical Electronic Engineering Department, Fourth Military Medical University, Xian, China.