[1] Univ Coll Hosp, Ctr Med Imaging, London NW1 2BU, England
[2] UCL, Dept Epidemiol & Publ Hlth, London, England
[3] UCL, Ctr Med Imaging, London, England
[4] Univ Birmingham, Dept Epidemiol, Birmingham, W Midlands, England
[5] Univ Birmingham, Dept Surg, Birmingham, W Midlands, England
[6] Univ London Imperial Coll Sci Technol & Med, Dept Surg & Canc, London, England