1. Department of Pediatric Radiology The Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
2. Department of Radiology, Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania USA
3. Department of Diagnostic Radiology, School of Clinical Medicine, Faculty of Health Sciences University of the Witwatersrand Johannesburg South Africa
4. Faculty of Medicine University of Glasgow Glasgow Scotland
5. Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Tygerberg Hospital Stellenbosch University Cape Town South Africa