Regional Blood FlowBlood Flow VelocityUltrasonography, DopplerUltrasonography, Doppler, ColorUltrasonographyUltrasonography, Doppler, PulsedDoppler EffectUltrasonography, Doppler, TranscranialCerebrovascular CirculationLaser-Doppler FlowmetryUltrasonography, PrenatalEchocardiography, Doppler, PulsedEchocardiography, Doppler, ColorPulsatile FlowSensitivity and SpecificityUltrasonography, Doppler, DuplexVascular ResistanceBlood PressureReproducibility of ResultsHemodynamicsProspective StudiesPregnancyContrast MediaEndosonographyFlow CytometryUltrasonography, InterventionalPredictive Value of TestsUmbilical ArteriesMagnetic Resonance ImagingMicrocirculationTime FactorsRheologyDogsArteriesNoninvasive VentilationXenon RadioisotopesCerebral ArteriesImaging, Three-DimensionalMicrospheresUltrasonography, MammaryMiddle Cerebral ArteryTomography, X-Ray ComputedOxygenHyperemiaLiver CirculationVasodilationPlacental CirculationHeart RateReference ValuesDiastolePlethysmographyTomography, Emission-ComputedCarotid ArteriesGestational AgeCarbon DioxideUterusOphthalmic ArteryRenal CirculationModels, CardiovascularObserver VariationCoronary CirculationSulfur HexafluoridePulmonary CirculationEchoencephalographyBrainFetal DiseasesOxygen ConsumptionImage EnhancementLegCollateral CirculationEchocardiographyBlood VolumeSplanchnic CirculationAngiographyImage Processing, Computer-AssistedDiagnostic ImagingVasodilator AgentsUltrasonicsCarotid Artery DiseasesRetrospective StudiesOxygen RadioisotopesSystoleFemoral ArteryPortal VeinMagnetic Resonance AngiographyFetal Growth RetardationTreatment OutcomeIschemiaArterial Occlusive DiseasesFetusFeasibility StudiesImage Interpretation, Computer-AssistedVentricular Function, LeftFetal HeartTomography, Emission-Computed, Single-PhotonFollow-Up StudiesVeinsInfant, NewbornXenonMitral Valve