1. Department of Pediatrics, Children’s Hospital of Western Ontario, London, Ontario, Canada
2. Departments of Epidemiology
3. Biostatistics, Montreal Children’s Hospital, McGill University, Montreal, Quebec, Canada
4. Department of Pediatrics, Ste-Justine Hospital, University of Montreal, Montreal, Quebec, Canada
5. Departments of Pediatrics
6. Radiology, Montreal Children’s Hospital, McGill University, Montreal, Quebec, Canada