Ho, Chi Long, 1. Department of Radiology, Sengkang General Hospital, Singapore 110 Sengkang East Way, Singapore 544886. 2. Duke-NUS Medical School, 8 College Road, Singapore 169857. 3. Yong Loo Lin School of Medicine, National University of Singapore, Singapore. 4. Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore., Singapore