1. Department of Surgery, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
2. Department of General Surgery, Baoding First Central Hospital, Baoding, Hebei 071000, P.R. China
3. Department of General Surgery, Cangzhou People's Hospital, Cangzhou, Hebei 061000, P.R. China
4. Department of Radiology, Cangzhou Central Hospital, Cangzhou, Hebei 061000, P.R. China