1. Department of Cardiology, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
2. Department of Radiology, Imperial College Healthcare NHS Trust, London W2 1NY, UK
3. Department of Radiology, Cambridge University Hospitals, Cambridge CB2 0QQ, UK
4. Department of Cardiology, Grochowski Hospital, Postgraduate Medical School, Warsaw 04-073, Poland