Qingqiang Ni1, Feng Xie2, Mengchao Wu3. 1. Medical College of Soochow University, Suzhou, Jiangsu, China; Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, China. 2. Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, China. Electronic address: xiefeng@smmu.edu.cn. 3. Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, China.