[1] Univ Coll, Inst Child Hlth, Dev Cognit Neurosci Unit, London WC1N 1EH, England
[2] Great Ormond St Hosp Children, Dept Radiol, London WC1N 3JH, England
[3] Royal London Hosp, Dept Paediat Haematol & Oncol, Queen Elizabeth Childrens Serv, London E1 1BB, England
[4] Univ Coll, Inst Child Hlth, Neurosci Unit, London WC1N 1EH, England
[5] Inst Child Hlth, Radiol & Phys Unit, London, England