[1] Department of Neuroradiology,
[2] Central Manchester Healthcare Trust,undefined
[3] Oxford Road,undefined
[4] Manchester M13 9WL,undefined
[5] UK,undefined
[6] Department of Diagnostic Radiology,undefined
[7] University of Manchester,undefined
[8] Manchester M13 9PT,undefined
[9] UK e-mail: AJackson@fs1.sdr.man.ac.uk,undefined
[10] Tel.: + 44-161-275 5056,undefined
[11] Fax: + 44-161-275 5594,undefined
[12] Department of Neurology,undefined
[13] Central Manchester Healthcare Trust,undefined
[14] Oxford Road,undefined
[15] Manchester M13 9WL,undefined
[16] UK,undefined