[1] Chiba Univ, Dept Gen Surg, Grad Sch Med, Chuo Ku, Chiba 2600856, Japan
[2] Chiba Univ, Dept Radiol, Grad Sch Med, Chiba 2600856, Japan
[3] Chiba Univ, Grad Sch Med, Dept Diagnost Pathol, Chiba 2600856, Japan
[4] Chiba Fdn Hlth Promot & Dis Prevent, Chiba, Japan