1. From the Department of Neuroradiology (D.P.), University of Western Ontario, London, Canada; the Karolinska Institute (T.A., M.S.), Stockholm, Sweden; the Department of Interventional Neuroradiology and Neurosurgery (P.L.), Clinica Medica Belgrano, Buenos Aires, Argentina; and Intervascular Neurosurgery (M.N.), Fujita Health University, Japan.