1. Optical Bioimaging Laboratory; Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore; 9 Engineering Drive 1 Singapore 117576 Singapore
2. Institute of Digestive Disease; Department of Gastroenterology, Zhongshan Hospital affiliated to Xiamen University; Xiamen 361004 China
3. Department of Medicine; Yong Loo Lin School of Medicine, National University of Singapore and National University Health System; Singapore 119260 Singapore
4. Department of Pathology; Yong Loo Lin School of Medicine, National University of Singapore and National University Health System; Singapore 119074 Singapore