School of Computer Science and Technology, Xidian University, No.2 South TaiBai Road, Xian, Peoples Republic of China.|Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Zhongshan Road, Guangzhou, Peoples Republic of China.|School of Statistics and Mathematics, Central University of Finance and Economics, 39 South College Road, Haidian District, Beijing, Peoples Republic of China.|School of Computer Science and Technology, Xidian University, No.2 South TaiBai Road, Xian, Peoples Republic of China.|Department of Nephrology, West China Hospital, Sichuan University, Wuhou District, Chengdu, Peoples Republic of China. tangwx@scu.edu.cn.