Affiliation: | (1) Department of Radiology, University of North Carolina School of Medicine, CB # 7510, Chapel Hill, NC 27599–7510, USA e-mail: castillo@med.unc.edu Tel.: 91 99 66 30 87 Fax: 91 99 66 19 94, US;(2) Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA, US |