1. From the University Department of Radiology (T.Y.T., M.J.G., Z.Y.L., V.Y., U.S., S.P.S.H., J.H.G.), Cambridge University Hospitals NHS Foundation Trust, UK; the Cambridge Vascular Unit (T.Y.T., S.R.W.), Cambridge University Hospitals NHS Foundation Trust, UK; and the Multi-Imaging Centre (K.H.M.), University of Cambridge, UK.