Species SpecificityPerfusionPerfusion ImagingCerebrovascular CirculationTomography, Emission-Computed, Single-PhotonTechnetium Tc 99m ExametazimePhylogenyBrainOrganotechnetium CompoundsDNA, RibosomalOximesSequence Analysis, DNAMolecular Sequence DataRNA, Ribosomal, 16SBlood-Brain BarrierBrain ChemistryBrain InjuriesBrain MappingBrain NeoplasmsIofetamineMagnetic Resonance ImagingBrain IschemiaRadiopharmaceuticalsOctanolsMyocardial Perfusion ImagingImage Processing, Computer-AssistedAcetazolamideAmphetaminesBrain EdemaRegional Blood FlowBrain StemSpin LabelsTomography, Emission-ComputedContrast MediaMagnetic Resonance AngiographyChoroid PlexusBlood Flow VelocityUltrasonography, Doppler, TranscranialRats, Sprague-DawleyAntipyrineCysteineTime FactorsTomography, X-Ray ComputedImage EnhancementReproducibility of ResultsImage Interpretation, Computer-AssistedAlzheimer DiseaseTissue DistributionBrain AbscessPhantoms, ImagingCapillariesSensitivity and SpecificityNeuronsCerebral CortexHypoxia, BrainNeuropsychological TestsBiological TransportAlgorithmsIodine RadioisotopesP-GlycoproteinChemotherapy, Cancer, Regional PerfusionCoronary CirculationBrain Damage, ChronicBrain InfarctionTreatment OutcomeDisease Models, AnimalRats, WistarDeep Brain StimulationHippocampusNerve Tissue ProteinsTechnetium Tc 99m SestamibiMicrocirculationOxygenMice, Inbred C57BLImmunohistochemistryAnimals, NewbornCerebellumRats, Inbred StrainsBrain WavesHeartAnalysis of VarianceAstrocytesAgingElectroencephalographyLaser-Doppler FlowmetryRNA, MessengerNeural PathwaysBlood VolumeBehavior, AnimalDogsNerve NetVentilation-Perfusion RatioGliomaCerebral VentriclesBrain Injury, ChronicAtrophyFrontal LobeThallium RadioisotopesBlood PressureDose-Response Relationship, Drug