Vertebral ArteryVertebrobasilar InsufficiencyBasilar ArteryVertebral Artery DissectionMagnetic Resonance AngiographySubarachnoid Hemorrhage, TraumaticCerebral AngiographyUltrasonography, Doppler, ColorUltrasonography, Doppler, DuplexIntracranial AneurysmArteriesAneurysm, DissectingAngioplasty, BalloonUltrasonography, Doppler, TranscranialSubclavian ArteryAngiography, Digital SubtractionCerebral ArteriesStentsCarotid Artery, InternalCarotid ArteriesSubclavian Steal SyndromeAngiographyArterial Occlusive DiseasesUltrasonographyRenal ArteryEchoencephalographyBlood Flow VelocityCarotid StenosisTomography, X-Ray ComputedPulmonary ArteryFemoral ArteryCircle of WillisSensitivity and SpecificityCarotid Artery DiseasesCerebrovascular CirculationCarotid Artery, ExternalMesenteric ArteriesVertigoCerebrovascular DisordersEmbolization, TherapeuticTemporal ArteriesCerebral VeinsSubarachnoid HemorrhageProspective StudiesIntracranial ArteriosclerosisLateral Medullary SyndromeConstriction, PathologicRenal Artery ObstructionAneurysm, RupturedIliac ArteryContrast MediaMammary ArteriesCarotid Artery, CommonRetrospective StudiesUltrasonography, DopplerCoronary Artery BypassPopliteal ArteryReproducibility of ResultsOccipital BoneFollow-Up StudiesTreatment OutcomeIschemic Attack, TransientCerebral InfarctionStrokeRadial ArteryCerebellar DiseasesIntracranial Embolism and ThrombosisVascular PatencyMagnetic Resonance ImagingCarotid Artery, Internal, DissectionCentral Nervous System Vascular MalformationsCervical VertebraeGiant Cell ArteritisBrain Stem InfarctionsHemifacial SpasmBrain IschemiaCervical AtlasFibromuscular DysplasiaNeck InjuriesBrachial ArteryCerebral RevascularizationRecurrenceSplenic ArteryTime FactorsPredictive Value of TestsHepatic ArteryVaricose VeinsInfarction, Posterior Cerebral ArteryAxisCeliac ArteryAngioplastyPosterior Cerebral ArteryMesenteric Artery, SuperiorBrachiocephalic TrunkCoronary VesselsAneurysmOphthalmic ArteryPhlebographyImaging, Three-DimensionalSaphenous Vein