1 UK National Interventional Radiology Trainee Research (UNITE) Collaborative, 63 Lincoln Inn Fields, London, WC2A 3JW, UK. indrajeet.mandal@ouh.nhs.uk.
2 John Radcliffe Hospital, Oxford University Hospitals NHS Trust, Headley Way, Oxford, Oxfordshire, OX3 9DU, UK. indrajeet.mandal@ouh.nhs.uk.
3 UK National Interventional Radiology Trainee Research (UNITE) Collaborative, 63 Lincoln Inn Fields, London, WC2A 3JW, UK.
4 St James's University Hospital, Leeds Teaching Hospitals NHS Trust, Beckett St, Harehills, Leeds, LS9 7TF, UK.
5 Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK.
6 Edinburgh Medical School, University of Edinburgh, 47 Little France Cres, Edinburgh, EH16 4TJ, Scotland.