1 Department of Radiology, Academic Medical Center, PO BOX 22660, 1100 DD Amsterdam, Netherlands; Department of Radiology, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht, Maastricht, Netherlands; Department of Neurology, Erasmus University Medical Center, Rotterdam, Netherlands. Electronic address: o.a.berkhemer@amc.uva.nl.
2 Department of Neurology, Erasmus University Medical Center, Rotterdam, Netherlands.