Takuya Toyonaga, MD, PhD
Research Scientist in Radiology and Biomedical ImagingCards
About
Research
Publications
Featured Publications
Optimized reference region and the effect on test-retest reliability and sensitivity to differences between Parkinson’s disease and control groups with [11C]UCB-J
Khattar N, Matuskey D, Gallezot J, Naganawa M, Holmes S, Sadabad F, Mayeli M, Esterlis I, van Dyck C, Mecca A, D’Souza D, Nabulsi N, Finnema S, Huang Y, Carson R, Toyonaga T. Optimized reference region and the effect on test-retest reliability and sensitivity to differences between Parkinson’s disease and control groups with [11C]UCB-J. Journal Of Cerebral Blood Flow And Metabolism : Official Journal Of The International Society Of Cerebral Blood Flow And Metabolism 2026, 0271678x261441071. PMID: 41960765, PMCID: PMC13068773, DOI: 10.1177/0271678x261441071.Peer-Reviewed Original ResearchHigh-resolution in utero SV2A PET imaging of the nonhuman primate brain using the NeuroEXPLORER.
Mehta S, Sun H, Micali N, Holden D, Fowles K, Rossano S, Zhang J, Ma C, Han P, Lee W, Duque A, Rakic P, Groman S, Carson R, Scheinost D, Toyonaga T. High-resolution in utero SV2A PET imaging of the nonhuman primate brain using the NeuroEXPLORER. Journal Of Cerebral Blood Flow And Metabolism : Official Journal Of The International Society Of Cerebral Blood Flow And Metabolism 2026, 271678x261429044. PMID: 41823342, PMCID: PMC12987752, DOI: 10.1177/0271678x261429044.Peer-Reviewed Original ResearchDistribution volume ratioMaternal brainIn vivo markerFetal brainPET imagingSynaptic developmentPregnant rhesus macaquesRegional distribution volume ratiosMarker of synaptic densitySynaptic vesicle glycoprotein 2APET scannerNon-invasive toolNonhuman primate brainPET quantificationBrain-dedicated PET scannersNeuroExplorerRhesus macaquesSynaptic densityBiograph mCTOccipital lobeOccipital regionBrainMotion correctionPETPrimate brainSV2A PET reveals synaptic density loss in experimental autoimmune encephalomyelitis and in a pilot multiple sclerosis study
Chia P, Toyonaga T, Tong J, Le H, Dias M, Boyle A, Raymond R, Longbrake E, Huang Y, Carson R, Airas L, Vasdev N, Chen M, Zheng C. SV2A PET reveals synaptic density loss in experimental autoimmune encephalomyelitis and in a pilot multiple sclerosis study. Proceedings Of The National Academy Of Sciences Of The United States Of America 2026, 123: e2517709123. PMID: 41774796, PMCID: PMC12974510, DOI: 10.1073/pnas.2517709123.Peer-Reviewed Original ResearchConceptsExperimental autoimmune encephalomyelitisMultiple sclerosisAutoimmune encephalomyelitisPET imagingSpinal cordExperimental autoimmune encephalomyelitis miceAge-matched healthy controlsQuantitative biomarkersLumbar spinal cordRegional distribution volumesDensity in vivoCross-species validationSynaptic vesicle glycoprotein 2APET findingsTracer uptakeSV2A bindingSynaptic pathologyHealthy controlsDisease progressionMouse modelMS patientsPathological featuresDistribution volumeMultiple Sclerosis StudySV2A levelsDevelopment and Initial Evaluation of 3D-Printed High Resolution Brain Phantom for PET
Lo C, Shanina E, Gravel P, Hu Y, Lucero S, Martins S, Mulnix T, Fontaine K, Nejati S, Sun X, Li H, Qi J, Cherry S, Carson R, Toyonaga T. Development and Initial Evaluation of 3D-Printed High Resolution Brain Phantom for PET. IEEE Transactions On Radiation And Plasma Medical Sciences 2025, PP: 1-1. PMID: 41446501, PMCID: PMC12724537, DOI: 10.1109/trpms.2025.3638588.Peer-Reviewed Original ResearchPET systemPET system performanceBrain PET systemHigh-resolution PET systemsSpatial resolutionSuperior spatial resolutionBrain phantomPhantom typesPhantom preparationPhantomReconstruction parametersRepositioning accuracyContrast modulationHuman brain anatomyReconstructed imagesMode dataContrast ratioImage resolutionHigh-resolution 3D printingResolutionAnatomical fidelityWhite matterGray matterModeFidelityExceptional brain PET images from the NeuroEXPLORER: scans with targeted radiopharmaceuticals and comparison to HRRT
Volpi T, Toyonaga T, Khattar N, Gallezot J, Naganawa M, Vanderlinden G, Honhar P, Zeng T, Fontaine K, Mulnix T, Hu L, Sun X, Henry S, Matuskey D, Radhakrishnan R, Guo L, Hu Y, Zhang J, Zheng X, Nabulsi N, Huang Y, Badawi R, Cherry S, Hillmer A, Jones T, Liu C, Morris E, Qi J, Li H, Carson R. Exceptional brain PET images from the NeuroEXPLORER: scans with targeted radiopharmaceuticals and comparison to HRRT. European Journal Of Nuclear Medicine And Molecular Imaging 2025, 53: 2110-2121. PMID: 41177836, PMCID: PMC12860869, DOI: 10.1007/s00259-025-07605-4.Peer-Reviewed Original ResearchStandardized uptake valueTargeted radiopharmaceuticalsDopamine systemMultiple cortical areasSerotonin transporterRaphe nucleusMeasurement of tracer uptakeBrain regionsBrain structuresSubcortical nucleiPositron emission tomographyCortical areasSynaptic densityPET researchFocal uptakePaired scansUptake valueTracer uptakePET systemGray matterEarly imagesEmission tomographyHealthy individualsTracer deliveryNeuroExplorerThe regional pattern of age-related synaptic loss in the human brain differs from gray matter volume loss: in vivo PET measurement with [11C]UCB-J
Toyonaga T, Khattar N, Wu Y, Lu Y, Naganawa M, Gallezot J, Matuskey D, Mecca A, Pittman B, Dias M, Nabulsi N, Finnema S, Chen M, Arnsten A, Radhakrishnan R, Skosnik P, D’Souza D, Esterlis I, Huang Y, van Dyck C, Carson R. The regional pattern of age-related synaptic loss in the human brain differs from gray matter volume loss: in vivo PET measurement with [11C]UCB-J. European Journal Of Nuclear Medicine And Molecular Imaging 2023, 51: 1012-1022. PMID: 37955791, PMCID: PMC12701775, DOI: 10.1007/s00259-023-06487-8.Peer-Reviewed Original ResearchSynaptic densityAge-related decreaseMagnetic resonance imagingBlood flowAge-related synaptic lossGray matter volume lossSynaptic density lossPositron emission tomography (PET) ligandSynaptic vesicle glycoprotein 2AVivo PET measurementsMedial occipital cortexGray matter volumeAge-related neurodegenerationGray matter regionsCognitive normal subjectsAge-related changesSynaptic lossNerve terminalsWide age rangeOccipital cortexTomography ligandNormal subjectsGM volumeAge-related functional lossesMatter volumeImaging the fetal nonhuman primate brain with SV2A positron emission tomography (PET)
Rossano S, Toyonaga T, Berg E, Lorence I, Fowles K, Nabulsi N, Ropchan J, Li S, Ye Y, Felchner Z, Kukis D, Huang Y, Benveniste H, Tarantal AF, Groman S, Carson RE. Imaging the fetal nonhuman primate brain with SV2A positron emission tomography (PET). European Journal Of Nuclear Medicine And Molecular Imaging 2022, 49: 3679-3691. PMID: 35633376, PMCID: PMC9826644, DOI: 10.1007/s00259-022-05825-6.Peer-Reviewed Original ResearchConceptsPositron emission tomographySynaptic densityFetal brainThird trimesterEmission tomographyBrain developmentGravid rhesus monkeysPost-mortem brain tissueEarly neonatal periodNonhuman primate brainLate gestational periodSubset of subjectsPostnatal brain developmentPost-mortem samplesGestational ageNeonatal periodPregnant monkeysSynapse numberGestational periodPrimary motorPrimate brainBrain growthSubcortical regionsBrain tissueCortical regionsPET Imaging of Synaptic Density: Challenges and Opportunities of Synaptic Vesicle Glycoprotein 2A PET in Small Animal Imaging
Toyonaga T, Fesharaki-Zadeh A, Strittmatter SM, Carson RE, Cai Z. PET Imaging of Synaptic Density: Challenges and Opportunities of Synaptic Vesicle Glycoprotein 2A PET in Small Animal Imaging. Frontiers In Neuroscience 2022, 16: 787404. PMID: 35345546, PMCID: PMC8957200, DOI: 10.3389/fnins.2022.787404.Peer-Reviewed Original ResearchAnimal modelsPET imaging studiesPET imagingImaging studiesSynaptic vesicle glycoprotein 2ADisease animal modelsOngoing clinical investigationsDifferent injection routesSynaptic densityClinical investigationPharmacological effectsRodent brainNovel interventionsInjection routeNeurodegenerative disordersNeuropsychiatric diseasesPET studiesBrainMultiple diseasesPET centersDiseaseInjectable volumeImagingSmaller brainsPETDeep learning–based attenuation correction for whole-body PET — a multi-tracer study with 18F-FDG, 68 Ga-DOTATATE, and 18F-Fluciclovine
Toyonaga T, Shao D, Shi L, Zhang J, Revilla EM, Menard D, Ankrah J, Hirata K, Chen MK, Onofrey JA, Lu Y. Deep learning–based attenuation correction for whole-body PET — a multi-tracer study with 18F-FDG, 68 Ga-DOTATATE, and 18F-Fluciclovine. European Journal Of Nuclear Medicine And Molecular Imaging 2022, 49: 3086-3097. PMID: 35277742, PMCID: PMC10725742, DOI: 10.1007/s00259-022-05748-2.Peer-Reviewed Original ResearchConceptsNeural networkNovel deep learningNet neural networkPET/CT datasetsImage analysis metricsPhysics-based loss functionDeep learningCT-derived attenuation mapAttenuation mapLoss functionAnalysis metricsDetail recoveryTumor volume estimationMLAACT datasetsOSEM algorithmNetworkAlgorithmAttenuation correctionCorrection frameworkFeasibility of imaging synaptic density in the human spinal cord using [11C]UCB-J PET
Rossano S, Toyonaga T, Bini J, Nabulsi N, Ropchan J, Cai Z, Huang Y, Carson RE. Feasibility of imaging synaptic density in the human spinal cord using [11C]UCB-J PET. EJNMMI Physics 2022, 9: 32. PMID: 35503134, PMCID: PMC9065222, DOI: 10.1186/s40658-022-00464-0.Peer-Reviewed Original ResearchFull spinal cordSpinal cord injuryHuman spinal cordSpinal cordAmyotrophic lateral sclerosisDistribution volume ratioCervical SCSynaptic densitySynaptic vesicle protein 2ACervical spinal cordBrain gray matterUse of PETBaseline VTWhole-body imagesSynapse lossCord injuryLateral sclerosisInjury severityGray matterNeurodegenerative disordersCordProtein 2AHuman dataDVR valuesCurrent standard
Academic Achievements & Community Involvement
Teaching & Mentoring
Mentoring
Sophie-Anne De Buyst
Medical student2026 - PresentSeyed Faraz Nejati, MD
Postdoctoral Associate2023 - Present