1. Department of Radiology Second Affiliated Hospital of Chongqing Medical University No. 74 Linjiang Rd, Yuzhong District Chongqing 400010 P. R. China
2. CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology of China No. 11, First North Road Zhongguancun Beijing 100190 P. R. China
3. University of Chinese Academy of Sciences Beijing 100049 P. R. China
4. State Key Laboratory of Ultrasound in Medicine and Engineering Chongqing Key Laboratory of Ultrasound Molecular Imaging & Ultrasound Department of the Second Affiliated Hospital of Chongqing Medical University No. 74 Linjiang Rd, Yuzhong District Chongqing 400010 P. R. China
5. Department of Radiology Renmin Hospital of Wuhan University No. 238 Jiefang Rd, Wuchang District Wuhan Hubei 430060 P. R. China