Department of Radiology & Functional and Molecular Imaging Key Lab of Shaanxi Province, Tangdu Hospital, Fourth Military Medical University (Air Force Medical University), 569 Xinsi Road, Xi'an, 710038, Shaanxi, China. Student Brigade, Fourth Military Medical University (Air Force Medical University), 169 West Changle Road, Xi'an, 710032, Shaanxi Province, China. Department of Clinical Nutrition, Xijing Hospital, The Fourth Military Medical University, Xi'an, China. Departments of Anesthesiology and Pharmacology, Louisiana State University School of Medicine, New Orleans, Louisiana, USA. Department of Radiology & Functional and Molecular Imaging Key Lab of Shaanxi Province, Tangdu Hospital, Fourth Military Medical University (Air Force Medical University), 569 Xinsi Road, Xi'an, 710038, Shaanxi, China. cgbtd@126.com. Department of Radiology & Functional and Molecular Imaging Key Lab of Shaanxi Province, Tangdu Hospital, Fourth Military Medical University (Air Force Medical University), 569 Xinsi Road, Xi'an, 710038, Shaanxi, China. wangwen@fmmu.edu.cn.