1. Department of Radiology, Addenbrooke's Hospital and University of Cambridge, Box 218, Cambridge Biomedical Campus, CB2 0QQ, Cambridge, UK.
2. Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan.
3. School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.
4. Division of Surgery & Interventional Science, University College London, London, UK.
5. Department of Radiology, University College London Hospital NHS Foundation Trust, London, UK.
6. Department of Urology, University College London Hospital NHS Foundation Trust, London, UK.