Angiography, Digital SubtractionBasilar ArterySubtraction TechniqueCerebral AngiographyMagnetic Resonance AngiographyIntracranial AneurysmVertebrobasilar InsufficiencyArteriesCerebral ArteriesCarotid Artery, InternalRadiographic Image EnhancementVertebral ArterySubarachnoid HemorrhageIntracranial Arteriovenous MalformationsImaging, Three-DimensionalEmbolization, TherapeuticContrast MediaTomography, X-Ray ComputedArterial Occlusive DiseasesSensitivity and SpecificityAngiographyVasospasm, IntracranialCarotid ArteriesAneurysm, RupturedImage Processing, Computer-AssistedRenal ArteryPulmonary ArteryCarotid StenosisCarotid Artery DiseasesFemoral ArterySalivary Gland CalculiCentral Nervous System Vascular MalformationsCerebrovascular CirculationBrain Stem InfarctionsConstriction, PathologicUltrasonography, Doppler, TranscranialUltrasonography, Doppler, ColorRadiography, Dental, DigitalReproducibility of ResultsCerebral VeinsUltrasonography, Doppler, DuplexIliac ArteryMesenteric ArteriesCircle of WillisIohexolAnterior Cerebral ArteryInjections, Intra-ArterialIntracranial ArteriosclerosisCerebrovascular DisordersObserver VariationX-Ray Intensifying ScreensMagnetic Resonance ImagingTomography, Spiral ComputedMiddle Cerebral ArteryAneurysmVasodilationTreatment OutcomeIschemic Attack, TransientVasoconstrictionArteriovenous MalformationsIopamidolRadiographic Image Interpretation, Computer-AssistedArtifactsCarotid Artery, ExternalPopliteal ArteryCeliac ArteryRetrospective StudiesCarotid-Cavernous Sinus FistulaSialographyGadolinium DTPARenal Artery ObstructionMuscle, Smooth, VascularSurgical InstrumentsPredictive Value of TestsCerebral RevascularizationTibial ArteriesCarotid Artery, CommonMyelographyProspective StudiesCoronary Artery BypassBrain IschemiaAngioplasty, BalloonRabbitsCerebral InfarctionNeurosurgical ProceduresDogsRadial ArterySalivary Gland DiseasesSubclavian ArteryRadiography, InterventionalVasodilator AgentsMammary ArteriesVascular PatencyCranial SinusesBlood Flow VelocityTime FactorsTriiodobenzoic AcidsRegional Blood FlowRadiography, BitewingIothalamate Meglumine