1. Department of Biomedical Sciences, City University of Hong Kong, 83, Tat Chee Avenue, Hong Kong SAR.
2. Department of Materials Science and Engineering, City University of Hong Kong, 83, Tat Chee Avenue, Hong Kong SAR.
3. Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83, Tat Chee Avenue, Hong Kong SAR.
4. Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins Medicine, Baltimore, MD, USA.