1. From the Centre for Medical Imaging, University College London, 3rd Floor East, 250 Euston Rd, London NW1 2PG, England (A.A.P., S.A.T., S.H.); Health and Medical Sciences Group, University of Cumbria, Lancaster, England (P.P.); Department of Primary Care Health Sciences, University of Oxford, Oxford, England (G.S., T.F.); Institute of Applied Health Sciences, University of Birmingham, Birmingham, England (S.M.).