1. College of Information Science and Engineering, Hunan Normal University, Changsha, P.R. China
2. College of Computer Science and Electronic Engineering, Hunan University, Changsha, P.R. China
3. College of Business, Hunan Normal University, Changsha, P.R. China
4. Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
5. Department of Computer Science and Bioimaging Research Center, The University of Georgia, Athens, GA, USA