XenonXenon RadioisotopesCerebral ArteriesCerebral InfarctionCerebrovascular CirculationCerebral PalsyAnesthetics, InhalationMiddle Cerebral ArteryBrainInfarction, Middle Cerebral ArteryCerebral AngiographyMalaria, CerebralBrain IschemiaCerebral VeinsCerebral HemorrhageNitrous OxideArgonNeuroprotective AgentsIsofluraneIschemic Attack, TransientMagnetic Resonance ImagingKryptonCerebrovascular DisordersAnterior Cerebral ArterySubarachnoid HemorrhageBlood Flow Velocity