Affiliation: | (1) Neuroradiology Department, Garcia de Orta Hospital, Portugal, PT;(2) Toronto Western Hospital, Division of Neuroradiology, Fell Pavilion 3–210, 399, Bathurst Street, Toronto ON M5T 2S8, Canada e-mail: robert.willinsky@uhn.on.ca Tel.: + 1-4 16-6 03 58 00 Fax: + 4 16-6 03 42 57, CA |