1. Department of Hepatobiliary Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong 250014, P.R. China
2. Department of Hepatobiliary Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong 250014, P.R. China
3. Department of Gastrointestinal Surgery, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong 264100, P.R. China