2023
Next generation PET imager
Pestotnik R, Gascón D, Gola A, Benlloch J, Alamo J, Barberá J, Dolenec R, Fernández-Tenllado J, Gómez S, Grogg K, Guberman D, Korpar S, Križan P, Majewski S, Manera R, Marin T, Mariscal-Castilla A, Mauricio J, Merzi S, Morera C, Orehar M, Pavon G, Penna M, Razdevšek G, Seljak A, Studen A, Fakhri G. Next generation PET imager. 2023, 00: 1-1. DOI: 10.1109/nssmicrtsd49126.2023.10338336.Peer-Reviewed Original ResearchPET imaging systemsReadout electronicsTime resolutionDetected scintillation photonsDual-sided readoutFast readout electronicsTime-of-flight measurementsLYSO crystal arrayFast-timing applicationsFlat-panel detectorTotal-body PET imagingScintillation photonsPET detectorsSilicon photomultipliersScintillation materialsXCAT phantomPET systemPanel detectorPhoto sensorCrystal arrayImaging systemTime spreadTiming precisionScintillationSignal-to-noise ratio
2021
Symmetric-Constrained Irregular Structure Inpainting for Brain MRI Registration with Tumor Pathology
Liu X, Xing F, Yang C, Kuo C, El Fakhri G, Woo J. Symmetric-Constrained Irregular Structure Inpainting for Brain MRI Registration with Tumor Pathology. Lecture Notes In Computer Science 2021, 12658: 80-91. PMID: 34013242, PMCID: PMC8130838, DOI: 10.1007/978-3-030-72084-1_8.Peer-Reviewed Original ResearchSimilarity measurePeak signal-to-noise ratioImage-to-image translationIncreased peak signal-to-noise ratioPatient imagesBrain MRI registrationMultimodal brain tumor segmentationStructural similarity indexRegistration similarity measurePatch-wise featuresBrain image registrationBrain tumor segmentationDeformable registrationStructure inpaintingInception ScoreRegistration of magnetic resonance imagesTumor regionInpainting frameworkInpainting methodRefinement moduleSignal-to-noise ratioSemantic relevanceMRI registrationOriginal patient dataSymmetry constraints
2020
PET imaging of neurotransmission using direct parametric reconstruction
Petibon Y, Alpert N, Ouyang J, Pizzagalli D, Cusin C, Fava M, Fakhri G, Normandin M. PET imaging of neurotransmission using direct parametric reconstruction. NeuroImage 2020, 221: 117154. PMID: 32679252, PMCID: PMC7800040, DOI: 10.1016/j.neuroimage.2020.117154.Peer-Reviewed Original ResearchConceptsSignal-to-noise ratioImage reconstructionPositron emission tomography image reconstructionLow signal-to-noise ratioPoisson log-likelihood functionScattered coincidencesDetector sensitivityPET sinogramsStatistical fluctuationsEstimate parametric imagesGradient-based optimizationParametric reconstructionLog-likelihood functionEffects of head movementVoxel scalePositron emission tomographySimplified reference region modelActivity concentration dataA Radio-Nano-Platform for T1/T2 Dual-Mode PET-MR Imaging
Gholami Y, Yuan H, Wilks M, Maschmeyer R, Normandin M, Josephson L, Fakhri G, Kuncic Z. A Radio-Nano-Platform for T1/T2 Dual-Mode PET-MR Imaging. International Journal Of Nanomedicine 2020, 15: 1253-1266. PMID: 32161456, PMCID: PMC7049573, DOI: 10.2147/ijn.s241971.Peer-Reviewed Original ResearchConceptsLine spread functionPET-MR imagingSignal-to-noise ratioFull-width half-maximum (FWHMPET-MRHalf-maximum (FWHMSpatial resolutionTransmission electron microscopyImage quality gainSimultaneous positron emission tomographyContrast-enhanced diagnostic imagingAtom adsorptionPhantom imagesPositron emission tomographySpatial resolution of MRHybrid PET-MRRadio-isotopesSpread functionMulti-modal imaging techniquesSensitivity of positron emission tomographyMagnetic resonanceCo-registeredTransmission electron microscopy analysisSuper paramagnetic iron oxide nanoparticlesContrast agents
2019
Arterial spin labeling MR image denoising and reconstruction using unsupervised deep learning
Gong K, Han P, Fakhri G, Ma C, Li Q. Arterial spin labeling MR image denoising and reconstruction using unsupervised deep learning. NMR In Biomedicine 2019, 35: e4224. PMID: 31865615, PMCID: PMC7306418, DOI: 10.1002/nbm.4224.Peer-Reviewed Original ResearchConceptsSignal-to-noise ratioImage denoisingReconstruction frameworkDeep learning-based image denoisingDeep learning-based denoisersMR image denoisingLearning-based denoisingLow signal-to-noise ratioK-space dataNoisy imagesTraining labelsTraining pairsNetwork inputNeural networkDenoisingIn vivo experiment dataSuperior performanceImaging speedReconstruction processImage qualityLong imaging timesNetworkFrameworkImagesSpatial resolutionPET Image Deblurring and Super-Resolution With an MR-Based Joint Entropy Prior
Song T, Yang F, Chowdhury S, Kim K, Johnson K, Fakhri G, Li Q, Dutta J. PET Image Deblurring and Super-Resolution With an MR-Based Joint Entropy Prior. IEEE Transactions On Computational Imaging 2019, 5: 530-539. PMID: 31723575, PMCID: PMC6853071, DOI: 10.1109/tci.2019.2913287.Peer-Reviewed Original ResearchContrast-to-noise ratioStructural similarity indexHoffman phantomImage deblurringDigital phantomPhantom studyPeak signal-to-noise ratioSuper-resolution frameworkQuantitative accuracySimilarity indexSignal-to-noise ratioSpatial resolutionPhantomImage quantitationSuper-resolutionTau imaging studiesImage qualityPET imagingDeblurringHigh-resolution MR imagingRoot mean square errorSimulation studyBrainWebPost-processingPenalty functionTime of flight PET reconstruction using nonuniform update for regional recovery uniformity
Kim K, Kim D, Yang J, Fakhri G, Seo Y, Fessler J, Li Q. Time of flight PET reconstruction using nonuniform update for regional recovery uniformity. Medical Physics 2019, 46: 649-664. PMID: 30508255, PMCID: PMC6501218, DOI: 10.1002/mp.13321.Peer-Reviewed Original ResearchConceptsSignal-to-noise ratio regionVariant step sizeSignal-to-noise ratioNesterov momentumOS-SQSUniform recoveryOS-EMStep sizeNon-TOF PETOrdered subsetsQuad-core CPUEarly stopping criterionGraphics processing unitsTime-of-flight PET reconstructionReconstruction methodPET reconstruction methodsNesterov's momentum methodImage qualityPET reconstructionTOF-PETOverall signal-to-noise ratioActive regionLow activity regionsComputer simulationsRecovery ratio
2018
Joint reconstruction of rest/stress myocardial perfusion SPECT
Lai X, Petibon Y, Fakhri G, Ouyang J. Joint reconstruction of rest/stress myocardial perfusion SPECT. Physics In Medicine And Biology 2018, 63: 135019. PMID: 29897044, PMCID: PMC6245543, DOI: 10.1088/1361-6560/aacc2f.Peer-Reviewed Original ResearchConceptsMyocardial perfusion imagingSingle photon emission computed tomographyReversible defectsSignal-to-noise ratioRest/stress SPECT myocardial perfusion imagingSPECT myocardial perfusion imagingConventional subtraction methodDefect detectionJoint methodPhoton emission computed tomographySubtraction methodReverse mappingClinical dose levelsEmission computed tomographyImprove defect detectionLow noiseNon-invasive assessmentClinical dosePerfusion defectsReduced doseImprove radiologists' performanceReconstruction frameworkRest imagesPerfusion imagingDose levels
2017
Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in vivo studies
Petibon Y, Rakvongthai Y, Fakhri G, Ouyang J. Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in vivo studies. Physics In Medicine And Biology 2017, 62: 3539-3565. PMID: 28379843, PMCID: PMC5739089, DOI: 10.1088/1361-6560/aa6394.Peer-Reviewed Original ResearchConceptsPET sinogramsSignal-to-noise ratioList-mode PET dataSiemens Biograph mMR scannerList-mode dataMyocardial perfusion imagingNoise realizationsPET myocardial perfusion imagingLow count levelsLeast-squares fitBiograph mMR scannerPET projection dataOriginal list-mode dataMyocardial blood flowCount levelsParametric reconstructionOSEMReconstruction methodIndependent noise realizationsNormal count levelsSinogramDirect reconstructionDynamic sinogramsKinetic modelPoor signal-to-noise ratio
2016
Numerical observer for atherosclerotic plaque classification in spectral computed tomography
Lorsakul A, Fakhri G, Worstell W, Ouyang J, Rakvongthai Y, Laine A, Li Q. Numerical observer for atherosclerotic plaque classification in spectral computed tomography. Journal Of Medical Imaging 2016, 3: 035501-035501. PMID: 27429999, PMCID: PMC4940624, DOI: 10.1117/1.jmi.3.3.035501.Peer-Reviewed Original ResearchSignal-to-noise ratioChannelized Hotelling observerMatched filterSignal-to-noise ratio improvementDual-energy CTMultienergy CTSpectral computed tomographyBinary classification taskHotelling observerNumerical observationsArea under the receiver operating characteristic curveObjective image assessmentAcquisition methodImage atherosclerotic plaquesMaterial characterizationComputed tomographyClassification taskPerformance metricsAnthropomorphic digital phantomIdentification applicationsSpectral CT dataConventional CT systemsCalcified plaqueSignal variationsAnalytical computation
2014
4D numerical observer for lesion detection in respiratory‐gated PET
Lorsakul A, Li Q, Trott C, Hoog C, Petibon Y, Ouyang J, Laine A, Fakhri G. 4D numerical observer for lesion detection in respiratory‐gated PET. Medical Physics 2014, 41: 102504. PMID: 25281979, PMCID: PMC4281099, DOI: 10.1118/1.4895975.Peer-Reviewed Original ResearchMeSH KeywordsAlgorithmsComputer SimulationFluorodeoxyglucose F18HumansImage Interpretation, Computer-AssistedLung DiseasesModels, BiologicalMonte Carlo MethodMotionPhantoms, ImagingPositron-Emission TomographyRadiopharmaceuticalsRegression AnalysisRespiratory-Gated Imaging TechniquesSignal-To-Noise RatioConceptsRespiratory-gated positron emission tomographyMotion-corrected imagesDetection signal-to-noise ratioLesion detection taskNumerical observationsLesion detection performanceSignal-to-noise ratioPositron emission tomography sinogramsSpherical lesionsHotelling observerMotion correction methodPositron emission tomographyGeant4 ApplicationTomographic EmissionChannelized Hotelling observerAnthropomorphic phantomScanner geometryOSEM algorithmMonte Carlo simulationsPET framesImprove lesion detectionLesion detectionSignal-to-noise ratio measurementsActivity distributionConventional 3D approachEffect of time‐of‐flight and point spread function modeling on detectability of myocardial defects in PET
Schaefferkoetter J, Ouyang J, Rakvongthai Y, Nappi C, El Fakhri G. Effect of time‐of‐flight and point spread function modeling on detectability of myocardial defects in PET. Medical Physics 2014, 41: 062502. PMID: 24877836, PMCID: PMC4032408, DOI: 10.1118/1.4875725.Peer-Reviewed Original ResearchConceptsSignal-to-noise ratioDetection signal-to-noise ratioPoint spread functionObserver signal-to-noise ratioEffects of time-of-flightMyocardial defectsHuman observer performanceDefect detectionSlow convergenceTime-of-flight (TOFNon-PSFPostreconstruction smoothingFDG-PET dataTime-of-flightPSF reconstructionCombination of TOFNon-TOFIterationObserver performanceClinical practiceSpread functionReconstruction parametersReconstruction protocolsIterative methodDetectionTof-Pet Ordered Subset Reconstruction Using Non-Uniform Separable Quadratic Surrogates Algorithm
Kim K, Ye J, Cheng L, Ying K, Fakhri G, Li Q. Tof-Pet Ordered Subset Reconstruction Using Non-Uniform Separable Quadratic Surrogates Algorithm. 2014, 963-966. DOI: 10.1109/isbi.2014.6868032.Peer-Reviewed Original ResearchSignal-to-noise ratioQuadratic surrogatesTOF-basedAlgorithm timeNoise ratioReconstruction algorithmReconstructed imagesAlgorithmConvergence rateImage qualityPET reconstructionTransmission reconstructionComputer simulationsTOF PET reconstructionTOF-PETEmission reconstructionAccurate imagingImagesSmall regionConvergenceComputerReconstructionNon-uniformityOSEMMotion compensation for brain PET imaging using wireless MR active markers in simultaneous PET–MR: Phantom and non-human primate studies
Huang C, Ackerman J, Petibon Y, Normandin M, Brady T, Fakhri G, Ouyang J. Motion compensation for brain PET imaging using wireless MR active markers in simultaneous PET–MR: Phantom and non-human primate studies. NeuroImage 2014, 91: 129-137. PMID: 24418501, PMCID: PMC3965607, DOI: 10.1016/j.neuroimage.2013.12.061.Peer-Reviewed Original ResearchConceptsMotion correctionWireless markersList-mode reconstructionReconstructed PET imagesMotion correction techniqueObserver signal-to-noise ratioSimultaneous PET-MRMotion artifactsPET phantomPET contrastPET reconstructionBrain PET imagingPET imagingPhantomBrain PETPET-MRIndependent noise realizationsAccurate quantitative valuesHead motionNoise realizationsPET dataSignal-to-noise ratioStatic referenceBrain PET scansActivation markers
2013
Spatially varying regularization for motion compensated PET reconstruction
Dutta J, Fakhri G, Lin Y, Huang C, Petibon Y, Reese T, Leahy R, Li Q. Spatially varying regularization for motion compensated PET reconstruction. 2011 IEEE Nuclear Science Symposium Conference Record 2013, 2156-2160. DOI: 10.1109/nssmic.2012.6551493.Peer-Reviewed Original ResearchSimulated lung lesionsRegularization schemeSpatially varying regularizationUngated reconstructionTorso phantomImage reconstruction problemContrast recoverySacrificing signal-to-noise ratioPET reconstructionSignal-to-noise ratioAnalytical approximationReconstruction frameworkQuadratic penaltyDiagonal elementsReconstruction problemLocal impulse responseCardiac motionRegularization approachReconstructed imagesFisher information matrixAutomated fashionPET imagingImpulse responseDegree of smoothnessInformation matrix
2012
MRI-Based Nonrigid Motion Correction in Simultaneous PET/MRI
Chun Y, Reese T, Ouyang J, Guerin B, Catana C, Zhu X, Alpert N, Fakhri G. MRI-Based Nonrigid Motion Correction in Simultaneous PET/MRI. Journal Of Nuclear Medicine 2012, 53: 1284-1291. PMID: 22743250, PMCID: PMC4077320, DOI: 10.2967/jnumed.111.092353.Peer-Reviewed Original ResearchConceptsChannelized Hotelling observerMotion correctionDetection signal-to-noise ratioSignal-to-noise ratioMRI-based motion correctionRespiratory motion correctionMotion-corrected reconstructionOrdered-subsets expectation maximization algorithmNonrigid motion correctionChannelized Hotelling observer studyPET image qualityNonrigid image registration methodCoincidence dataDeformable phantomRespiratory gatingReduce radiation doseDynamic phantomImage registration methodReduced signal-to-noise ratioSimultaneous PET/MRICost of increased noiseHotelling observerPhantomAttenuation measurementsRabbit studies
2007
Fast Monte Carlo based joint iterative reconstruction for simultaneous SPECT imaging
Ouyang J, Fakhri G, Moore S. Fast Monte Carlo based joint iterative reconstruction for simultaneous SPECT imaging. Medical Physics 2007, 34: 3263-3272. PMID: 17879789, DOI: 10.1118/1.2756601.Peer-Reviewed Original ResearchConceptsMC-JOSEMEnergy windowFast Monte CarloSignal-to-noise ratioScatter correction methodOrdered-subsets expectation-maximizationMonte CarloOrdered-subsets expectation-maximization algorithmIterative reconstruction algorithmPrimary photonsReconstruction algorithmPhoton transportSeptal penetrationDetector responseMC simulationsIterative reconstructionAttenuation distributionStandard OSEMPhotonsProjection dataPatient-specific activityDetectorReconstructed imagesScatteringEstimation of scattering
2006
Optimizing Acquisition Parameters in TOF PET Scanners
Surti S, El-Fakhri G, Karp J. Optimizing Acquisition Parameters in TOF PET Scanners. 2006, 4: 2354-2359. DOI: 10.1109/nssmic.2006.354386.Peer-Reviewed Original ResearchNoise equivalent countCho SNRNon-TOF scannerScan timePET image qualityPatient dosageTime-of-flightSingles ratesOptimal acquisition parametersPET scannerTOF scannerDiameter cylinderIncreasing scan timeImage qualityReduce scan timeMeasure of signal-to-noise ratioSignal-to-noise ratioSpatial resolutionSNRAcquisition parametersLesion detectionLesionsTOFCylinderIncreased activity
2005
Performance of a novel collimator for high‐sensitivity brain SPECT
Fakhri G, Ouyang J, Zimmerman R, Fischman A, Kijewski M. Performance of a novel collimator for high‐sensitivity brain SPECT. Medical Physics 2005, 33: 209-215. PMID: 16485427, DOI: 10.1118/1.2143140.Peer-Reviewed Original ResearchConceptsSphere activity concentrationNPW-SNRStandard collimatorSphere-to-background activity ratiosAttenuation of countsPhantom centerActivity concentrationsPoint spread functionCentral regionCollimatorPhantom studyStriatal phantomCylindrical backgroundResolution recoveryPhantomSpherical lesionsRamp filterCrystal surfaceSpread functionSignal-to-noise ratioCentral brain structuresFitting imageHealthy volunteersBrain SPECTSphere activity
2003
A Multi-Scanner Evaluation of PET Image Quality Using Phantom Studies
Surti S, Badawi R, Holdsworth C, Fakhri G, Kinahan P, Karp J. A Multi-Scanner Evaluation of PET Image Quality Using Phantom Studies. 2003, 4: 2425-2427. DOI: 10.1109/nssmic.2003.1352384.Peer-Reviewed Original ResearchSignal-to-noise ratioImage signal-to-noisePET image qualityImage signal-to-noise ratioDiameter phantomImage qualityPhantom diameterPET scannerNEC ratesPhantom studyMeasures of image qualitySignal-to-noisePhantomAcquisition modeFilter observerSpecific tasksAccurate measurementRate dropsSinogramScannerPreliminary resultsECAT