1. Center for Brain Imaging, School of Life Science and Technology, Xidian University, Xi’an, Shaanxi 710071, China
2. State Key Laboratory of Cancer Biology, National Clinical Research Center for Digestive Diseases and Xijing Hospital of Digestive Diseases, Air Force Medical University, Xi’an, Shaanxi 710032, China
3. Department of Radiology, Tangdu Hospital, Air Force Medical University, Xi’an, Shaanxi 710038, China
4. Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892, USA