1. From the Department of Academic Radiology, Medical School (A.R.M., R.E.M., P.S.M., A.L.M., G.S.D., S.A.), the Department of Vascular Surgery (S.T.M., W.G.T.), the Ageing and Disability Research Unit (J.G.), and the Department of Neuropathology (J.L.), University Hospital, Nottingham, and the Department of Haematology, Guy’s and St Thomas’s Trust, London (B.J.H.), UK.