1. Department of General Surgery, First Hospital of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
2. Department of Nuclear Magnetic Resonance, The Second Clinical Medical College of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
3. Department of General Surgery, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650000, P.R China