1. Department of Ultrasound, Peking University Third Hospital, Beijing 100191, P. R. China
2. Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Medicine, Northwest University, Xi’an 710069, P. R. China
3. CAS Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, University of Chinese Academy of Sciences, Beijing 100190, P. R. China
4. School of Basic Medical Sciences, Peking University, Beijing 100190, P. R. China