[1] Department of Radiology,
[2] University Hospital Nottingham,undefined
[3] Queen's Medical Centre,undefined
[4] Derby Road,undefined
[5] Nottingham,undefined
[6] NG7 2UH,undefined
[7] UK e-mail: robert.lenthall@mail.qmcuh-tr. trent.nhs.uk Tel.: + 44-115-9 249924 ext. 42311 Fax: + 44-1 15-9 42 49 94,undefined
[8] Department of Neurosurgery,undefined
[9] University Hospital Nottingham,undefined
[10] Queen's Medical Centre,undefined
[11] Derby Road,undefined
[12] Nottingham,undefined
[13] NG7 2UH,undefined
[14] UK,undefined