From the Department of Neurology and Neurological Sciences (S.L., M.M., S.C.), Stanford Stroke Center, Stanford University School of Medicine, CA; Division of Child Neurology (S.L.), Department of Neurology and Neurological Sciences, Stanford University School of Medicine, CA; Division of Neuroradiology (B.J.), Department of Radiology, Stanford University School of Medicine, CA; Department of Neuroradiology (M.W.), University of Texas MD Anderson, Houston, TX; Department of Pediatrics (R.S.), University Hospital of Muenster; Department of Diagnostic and Interventional Neuroradiology (G.B., J.F.), University Medical Center Hamburg-Eppendorf, Germany; Department of Neuroradiology (A.G.), Medical University of Innsbruck, Austria; Department of Neuroradiology (O.N.), RWTH Aachen University, Germany; Department of Neurological Sciences and Vision (A.M.), Neurology Unit, ASST Spedali Civili, Brescia, Italy; Department of Neuroradiology (J.T.), Kepler University Hospital, Johannes Kepler University Linz, Austria; Department of Neuroradiology (M.M.), Heidelberg University Hospital; Department of Radiology (M.W.), University Hospital, LMU Munich; Department of Neuroradiology (A.K.), Marburg University Hospital, Germany; Department of Neuroradiology (M.P., P.B.S.), Clinic for Radiology and Nuclear Medicine, University Hospital Basel, Switzerland.