1 Radiological Sciences, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham.
2 Medical Physics and Clinical Engineering, Nottingham University Hospitals NHS Trust.
3 NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and the University of Nottingham; Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.