1. Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, UK
2. MRC Population Health Research Unit, University of Oxford, UK
3. Division of Ultrasound Diagnosis, Peking Union Medical College Hospital, Beijing, China
4. Chinese Academy of Medical Sciences, Beijing, China
5. Centre of Vascular Surgery, Peking Union Medical College Hospital, Beijing, China
6. Department of Radiology, University Medical Centre Utrecht, The Netherlands
7. Department of Epidemiology and Statistics, School of Public Health, Peking University Health Science Centre, Beijing, China