Published ahead of print on November 19, 2009 doi: 10.3174/ajnr.A1951 American Journal of Neuroradiology 31:E32, March 2010 © 2010 American Society of Neuroradiology P.J. MacMahona, I. Crosbiea and E.C. Kavanagha aDepartment of Radiology Mater Misericordiae University Hospital Dublin, Ireland We read with great interest