1. College of Medical Imaging Shanxi Medical University Taiyuan 030001 Shanxi China
2. College of Basic Medicine Shanxi Medical University Taiyuan 030001 Shanxi China
3. Department of Radiology Memorial Sloan Kettering Cancer Center New York NY 10065 USA
4. School of Public Health, Health Science Center Xi'an Jiaotong University No.76 Yanta West Road Xi'an 710061 Shaanxi China