Angiography, Digital SubtractionCerebral AngiographyMagnetic Resonance AngiographyIntracranial AneurysmAngiographySubtraction TechniqueIntracranial Arteriovenous MalformationsTomography, X-Ray ComputedImaging, Three-DimensionalEmbolization, TherapeuticContrast MediaCarotid Artery, InternalCentral Nervous System Vascular MalformationsSubarachnoid HemorrhageCoronary AngiographyAneurysm, RupturedSensitivity and SpecificityCerebral ArteriesRadiographic Image EnhancementCerebral VeinsArterial Occlusive DiseasesCarotid StenosisCranial SinusesImage Processing, Computer-AssistedArteriovenous MalformationsConstriction, PathologicCarotid Artery DiseasesTomography, Spiral ComputedVertebrobasilar InsufficiencyVertebral ArteryCerebrovascular DisordersCerebrovascular CirculationUltrasonography, Doppler, DuplexAnterior Cerebral ArteryCerebral InfarctionVasospasm, IntracranialUltrasonography, Doppler, ColorIopamidolBasilar ArteryCircle of WillisCarotid-Cavernous Sinus FistulaMoyamoya DiseaseCerebral RevascularizationReproducibility of ResultsIohexolMagnetic Resonance ImagingIschemic Attack, TransientSurgical InstrumentsArteriovenous FistulaObserver VariationUltrasonography, Doppler, TranscranialIntracranial ArteriosclerosisBrain IschemiaGadolinium DTPAMiddle Cerebral ArteryNeurosurgical ProceduresX-Ray Intensifying ScreensRetrospective StudiesCarotid ArteriesPredictive Value of TestsRadiographic Image Interpretation, Computer-AssistedCerebral HemorrhageProspective StudiesArtifactsEndarterectomyIothalamate MeglumineAneurysmBlood Flow VelocityFluorescein AngiographyTibial ArteriesInjections, Intra-ArterialRadiography, InterventionalTreatment OutcomeCollateral CirculationTriiodobenzoic AcidsUltrasonographyCavernous SinusRenal ArteryCarotid Artery, ExternalImage EnhancementFollow-Up StudiesUltrasonography, DopplerVascular PatencyBrainAortographyPosterior Cerebral ArteryRadiation DosageEndarterectomy, CarotidPopliteal ArteryStentsTime FactorsFeasibility StudiesFalse Negative ReactionsGadoliniumAngioplasty, BalloonPreoperative CareArteriesSeverity of Illness IndexFemoral ArteryRegional Blood Flow