1. Centre for Cardiovascular Imaging, Institute of Cardiovascular Science, University College London, London, UK
2. Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, Level 7, Nurses Home, Great Ormond Street, London WC1N 3JH, UK
3. Deparetment of Paediatrics, Paediatric Cardiology Division, CH Baragwanath Academic Hospital and University of the Wiwatersrand, Johannesburg, South Africa
4. Department of Imaging, Bambino Gesù Children's Hospital, Rome, Italy