1. From the Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom (D.T., M.J.F., J.T.O.B., G.A.F.); Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (J.H., A.M.B.); and Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle upon Tyne, United Kingdom (J.H., M.J.F., J.T.O.B., A.M.B.).