1. Department of Head and Neck Surgery, University College London Hospitals NHS Foundation Trust, London, UK
2. Department of Upper Gastro-Intestinal Surgery, University College London Hospitals NHS Foundation Trust, London, UK
3. Department of Metabolism, Digestion & Reproduction, Hammersmith Hospital Clinical Research Facility, Imperial College London, London, UK
4. Department of Vascular Surgery, Royal Free London NHS Foundation Trust, London, UK
5. Department of Vascular Surgery, University College London Hospitals NHS Foundation Trust, London, UK
6. Department of Radiology, University College London Hospitals NHS Foundation Trust, London, UK
7. Department of Radiology, Royal Free London NHS Foundation Trust, London, UK