Dehong Cao1, Lin Bai2, Liangren Liu1, Jia Wang1, Qiang Wei1. 1. 1 Department of Urology, Institute of Urology, West China Hospital, SiChuan University , Chengdu, China . 2. 2 Experiment Teaching Center of Clinical Medicine , The First Affiliated Hospital of Chengdu Medical College, Chengdu, China .