1 Department of Radiology, St George's University of London and St George's University Hospitals NHS Foundation Trust, London, UK. Electronic address: robert.morgan@stgeorges.nhs.uk.
2 Department of Interventional Radiology, Sheffield Vascular Institute, Sheffield Teaching Hospitals, Sheffield, UK.
3 Department of Interventional Radiology, Imperial College Healthcare NHS Trust, London, UK.
4 Department of Interventional Radiology, Oxford University Hospitals, Oxford, UK.
5 Department of Interventional Radiology, Freeman Hospital, Newcastle, UK.
6 Department of Interventional Radiology, Greater Glasgow & Clyde NHS, Queen Elizabeth University Hospital, Glasgow, UK.
7 Department of Interventional Radiology, University Hospitals Sussex and Brighton and Sussex Medical School, Brighton, UK.
8 Department of Interventional Radiology, University Hospital Birmingham, Birmingham and Women's NHS Trust, Birmingham, UK.