Ultrasonography, Doppler, TranscranialUltrasonography, DopplerBlood Flow VelocityCerebrovascular CirculationUltrasonography, Doppler, ColorUltrasonographyEchoencephalographyCerebral ArteriesMiddle Cerebral ArteryIntracranial Embolism and ThrombosisUltrasonography, Doppler, PulsedRegional Blood FlowIntracranial PressureValsalva ManeuverBrain Hemorrhage, TraumaticTranscranial Magnetic StimulationCerebrovascular DisordersAnemia, Sickle CellArterial Occlusive DiseasesHeart Septal Defects, AtrialUltrasonography, Doppler, DuplexDoppler EffectPulsatile FlowProspective StudiesIschemic Attack, TransientUltrasonography, PrenatalCerebral AngiographyIntracranial EmbolismCarbon DioxideStrokeBrain IschemiaBlood PressureSensitivity and SpecificityBrainEchocardiography, Doppler, PulsedVascular ResistanceCarotid StenosisEchocardiography, Doppler, ColorReproducibility of ResultsUmbilical ArteriesPredictive Value of TestsLaser-Doppler FlowmetryEvoked Potentials, MotorCarotid Artery, InternalHemodynamicsContrast MediaPregnancyOphthalmic ArteryCarotid Artery DiseasesTomography, X-Ray ComputedBasilar ArteryMonitoring, IntraoperativeEmbolism, AirPlacental CirculationTime FactorsMagnetic Resonance ImagingUltrasonicsVertebral ArteryCircle of WillisCollateral CirculationPortal VeinArteriesCarotid ArteriesReference ValuesScrotumEndarterectomy, CarotidUltrasonography, InterventionalTreatment OutcomeFetal DiseasesMonitoring, PhysiologicSubclavian Steal SyndromeAcetazolamideConstriction, PathologicMotor CortexCerebral Arterial DiseasesEndosonographyMagnetic Resonance AngiographyObserver VariationVasospasm, IntracranialAngiography, Digital SubtractionTesticular DiseasesUterusEmbolism, ParadoxicalHypocapniaRetrospective StudiesFollow-Up StudiesMicrocirculationHepatic VeinsLiver CirculationAngiographyGestational AgeSubarachnoid HemorrhageForamen Ovale, PatentIntracranial Arterial DiseasesPortographyHomeostasisFetal Growth RetardationImaging, Three-DimensionalAcute DiseaseRenal Artery