2022
Memory consistent unsupervised off-the-shelf model adaptation for source-relaxed medical image segmentation
Liu X, Xing F, El Fakhri G, Woo J. Memory consistent unsupervised off-the-shelf model adaptation for source-relaxed medical image segmentation. Medical Image Analysis 2022, 83: 102641. PMID: 36265264, PMCID: PMC10016738, DOI: 10.1016/j.media.2022.102641.Peer-Reviewed Original ResearchConceptsUnsupervised domain adaptationUnsupervised domain adaptation methodsSource domain dataBN statisticsTarget domainLabeled source domain dataDomain dataLabeled source domainSelf-training strategyPatient data privacyHeterogeneous target domainBrain tumor segmentationPseudo-labelsDomain adaptationUnsupervised adaptationData privacySegmentation taskSource domainImage segmentationVital protocolAdaptation frameworkDecay strategyBoost performanceModel adaptationTumor segmentation
2021
Free‐breathing 3D cardiac T1 mapping with transmit B1 correction at 3T
Han P, Marin T, Djebra Y, Landes V, Zhuo Y, Fakhri G, Ma C. Free‐breathing 3D cardiac T1 mapping with transmit B1 correction at 3T. Magnetic Resonance In Medicine 2021, 87: 1832-1845. PMID: 34812547, PMCID: PMC8810588, DOI: 10.1002/mrm.29097.Peer-Reviewed Original ResearchConceptsFlip-angle estimationCardiac T<sub>1</sub> mappingGradient echo readoutThrough-plane spatial resolutionImaging timePractical imaging timesFree breathingPhantom studyB1 correctionAccelerated imagingIn-planeT)-spaceMyocardial T<sub>1</sub> valuesSubspace-based methodsSpatial resolutionImaging experimentsAcquisition schemeT)-space dataSubject-specific timeCorrectionModified Look-Locker inversion recoveryLook-Locker inversion recoveryTime of data acquisitionAverage imaging timeInversion-recovery sequenceSegmentation of Cardiac Structures via Successive Subspace Learning with Saab Transform from Cine MRI
Liu X, Xing F, Gaggin H, Wang W, Kuo C, Fakhri G, Woo J. Segmentation of Cardiac Structures via Successive Subspace Learning with Saab Transform from Cine MRI. Annual International Conference Of The IEEE Engineering In Medicine And Biology Society (EMBC) 2021, 00: 3535-3538. PMID: 34892002, DOI: 10.1109/embc46164.2021.9629770.Peer-Reviewed Original ResearchConceptsConvolutional neural networkSegmentation of cardiac structuresSaab transformSubspace approximationAccurate segmentation of cardiac structuresDimension reductionConvolutional neural network modelConcatenation of featuresUnsupervised dimension reductionConditional random fieldPixel-wise classificationSupervised dimension reductionU-Net modelMachine learning modelsSubspace learningChannel-wiseSegmentation databaseSegmentation frameworkNeural networkU-NetEfficient segmentationAccurate segmentationLearning modelsCardiac MR imagesRandom field
2019
Body motion detection and correction in cardiac PET: Phantom and human studies
Sun T, Petibon Y, Han P, Ma C, Kim S, Alpert N, Fakhri G, Ouyang J. Body motion detection and correction in cardiac PET: Phantom and human studies. Medical Physics 2019, 46: 4898-4906. PMID: 31508827, PMCID: PMC6842053, DOI: 10.1002/mp.13815.Peer-Reviewed Original ResearchConceptsList-mode dataMotion-compensated image reconstructionMotion correctionCenter of massPET list-mode dataMotion correction methodMotion detectionMotion estimationImage reconstructionPatient body motionDegrade image qualityNonrigid registrationImage qualityMotion transformationCoincident distributionBody motion detectionCardiac positron emission tomographyBack-projection techniqueCovariance matrixImage volumesBody motionPositron emission tomographyBack-projectionReference framePhantomMR-based cardiac and respiratory motion correction of PET: application to static and dynamic cardiac 18F-FDG imaging
Petibon Y, Sun T, Han P, Ma C, Fakhri G, Ouyang J. MR-based cardiac and respiratory motion correction of PET: application to static and dynamic cardiac 18F-FDG imaging. Physics In Medicine And Biology 2019, 64: 195009. PMID: 31394518, PMCID: PMC7007962, DOI: 10.1088/1361-6560/ab39c2.Peer-Reviewed Original ResearchConceptsMR-based motion correctionRespiratory motion correctionMotion correctionImproved spatial resolutionReconstructed activity concentrationCardiac PET dataSpatial resolutionCoincidence eventsMR-basedPET imagingContrast-to-noise ratioCardiac PET imagingRespiratory phasesMC dataImprove image qualityMR acquisitionQuantitative accuracyCardiac PETPET dataActivity concentrationsMyocardium wallF-FDG PETDynamics studiesImage qualityMotion artifactsFree-Breathing Three-Dimensional T1 Mapping of the Heart Using Subspace-Based Data Acquisition and Image Reconstruction
Han P, Horng D, Marin T, Petibon Y, Ouyang J, Fakhri G, Ma C. Free-Breathing Three-Dimensional T1 Mapping of the Heart Using Subspace-Based Data Acquisition and Image Reconstruction. Annual International Conference Of The IEEE Engineering In Medicine And Biology Society (EMBC) 2019, 00: 4008-4011. PMID: 31946750, DOI: 10.1109/embc.2019.8856511.Peer-Reviewed Original ResearchConceptsRespiratory motionRespiratory gatingLongitudinal relaxation timeSubspace-based methodsLow-rank tensorMagnetic resonance imagingRelaxation timeT1 mappingT)-spaceSubspace-basedSparsity constraintDynamic MR imagingReconstructed mapsSpatiotemporal correlationThree-dimensionalCardiac MRHealthy subjectsIn vivo dataMagnetizationResonance imagingImage functionMR imagingData acquisitionClinical applicationTensor
2018
Advances in coronary molecular imaging: Leveraging the power of image processing
Abdelbaky A, El Fakhri G, Tawakol A. Advances in coronary molecular imaging: Leveraging the power of image processing. Journal Of Nuclear Cardiology 2018, 27: 505-507. PMID: 30367381, PMCID: PMC6486447, DOI: 10.1007/s12350-018-1454-x.Peer-Reviewed Original Research
2015
Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET‐MR: Phantom and patient studies
Huang C, Petibon Y, Ouyang J, Reese T, Ahlman M, Bluemke D, El Fakhri G. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET‐MR: Phantom and patient studies. Medical Physics 2015, 42: 1087-1097. PMID: 25652521, PMCID: PMC4312342, DOI: 10.1118/1.4906247.Peer-Reviewed Original ResearchConceptsPET motion correctionMotion correctionSimultaneous PET-MRTMR dataPET list-mode dataPET-MRList-mode dataCardiac motion correctionPET-MR scannersImage qualityParallel imagingAcquisition timePET imagingRespiratory motionCompressive sensingMotion fieldAttenuation correctionDefect contrastModerate acceleration factorsDegradation of image qualityTagged MRCardiac phantomLong acquisition timesPhantomAccurate motion field
2014
Effect 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 methodDetection
2013
Direct reconstruction of cardiac PET kinetic parametric images using a preconditioned conjugate gradient approach
Rakvongthai Y, Ouyang J, Guerin B, Li Q, Alpert N, Fakhri G. Direct reconstruction of cardiac PET kinetic parametric images using a preconditioned conjugate gradient approach. Medical Physics 2013, 40: 102501. PMID: 24089922, PMCID: PMC3779266, DOI: 10.1118/1.4819821.Peer-Reviewed Original ResearchCardiac motion compensation and resolution modeling in simultaneous PET-MR: a cardiac lesion detection study
Petibon Y, Ouyang J, Zhu X, Huang C, Reese T, Chun S, Li Q, Fakhri G. Cardiac motion compensation and resolution modeling in simultaneous PET-MR: a cardiac lesion detection study. Physics In Medicine And Biology 2013, 58: 2085-2102. PMID: 23470288, PMCID: PMC3657754, DOI: 10.1088/0031-9155/58/7/2085.Peer-Reviewed Original ResearchConceptsContrast recoveryDetector point spread functionPartial volume effectsK-spaceMotion compensationB-spline registrationLesion-detection studiesCardiac motion compensationPET-MR scannersSimultaneous PET-MRPET contrastIterative reconstruction frameworkPoint spread functionMotion correctionPET countsNon-rigid B-spline registrationCardiac phantomPSF modelPET-MRMotion deblurringReconstruction frameworkSystem matrixCardiac PETSpread functionDefect detection
2012
Single‐scan rest/stress imaging 18F‐labeled flow tracers
Alpert N, Fang Y, Fakhri G. Single‐scan rest/stress imaging 18F‐labeled flow tracers. Medical Physics 2012, 39: 6609-6620. PMID: 23127055, PMCID: PMC3482258, DOI: 10.1118/1.4754585.Peer-Reviewed Original Research
2009
Quantitative simultaneous cardiac SPECT using MC‐JOSEM
Ouyang J, Zhu X, Trott C, Fakhri G. Quantitative simultaneous cardiac SPECT using MC‐JOSEM. Medical Physics 2009, 36: 602-611. PMID: 19292000, PMCID: PMC2673670, DOI: 10.1118/1.3063544.Peer-Reviewed Original ResearchConceptsMC-JOSEMEnergy windowWater-filled torso phantomScatter correctionPhotopeak energy windowStandard OSEMCardiac SPECT imagingActivity concentration ratioIterative reconstruction algorithmReconstruction algorithmMyocardium wallTorso phantomActivity estimationDetector responseEmission energyBackground compartmentPhantom dataCardiac SPECTActivity distributionRest/stress imagingScatteringCases of patientsOSEMChest painCardiac protocols
2008
Quantitative relationship between coronary vasodilator reserve assessed by 82Rb PET imaging and coronary artery stenosis severity
Anagnostopoulos C, Almonacid A, El Fakhri G, Curillova Z, Sitek A, Roughton M, Dorbala S, Popma J, Di Carli M. Quantitative relationship between coronary vasodilator reserve assessed by 82Rb PET imaging and coronary artery stenosis severity. European Journal Of Nuclear Medicine And Molecular Imaging 2008, 35: 1593-1601. PMID: 18425513, PMCID: PMC3124702, DOI: 10.1007/s00259-008-0793-2.Peer-Reviewed Original ResearchConceptsPositron emission tomographyCoronary artery diseaseCoronary vasodilator reserveMyocardial blood flowPositron emission tomography imagingPercent diameter stenosisDiameter stenosisEmission tomographyAge-matchedStenosis severityHyperaemic myocardial blood flowRisk factorsStress myocardial blood flowVasodilator reserveFunctional assessment of coronary artery diseaseAssessment of coronary artery diseaseClinically useful tool
2005
Quantitative dynamic cardiac 82Rb PET using generalized factor and compartment analyses.
El Fakhri G, Sitek A, Guérin B, Kijewski M, Di Carli M, Moore S. Quantitative dynamic cardiac 82Rb PET using generalized factor and compartment analyses. Journal Of Nuclear Medicine 2005, 46: 1264-71. PMID: 16085581.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAged, 80 and overAlgorithmsComputer SimulationCoronary Artery DiseaseFeasibility StudiesFemaleHeartHumansImage Interpretation, Computer-AssistedMaleMiddle AgedModels, CardiovascularPositron-Emission TomographyRadiopharmaceuticalsReproducibility of ResultsRubidium RadioisotopesSensitivity and SpecificitySeverity of Illness IndexConceptsMyocardial perfusionAbsolute myocardial perfusionCatheterization resultsMyocardial tissue extractsDipyridamole stressCardiac PETClinical valueMyocardial factorsFactor analysis of dynamic sequencesPatient studiesLVNoninvasive estimationAccurate input functionPatientsCompartment analysisAverage errorPerfusionParametric mappingTissue extractsRV contributionRV
2000
Relative impact of scatter, collimator response, attenuation, and finite spatial resolution corrections in cardiac SPECT.
El Fakhri G, Buvat I, Benali H, Todd-Pokropek A, Di Paola R. Relative impact of scatter, collimator response, attenuation, and finite spatial resolution corrections in cardiac SPECT. Journal Of Nuclear Medicine 2000, 41: 1400-8. PMID: 10945534.Peer-Reviewed Original ResearchConceptsDepth-dependent collimator responseSpatial resolution correctionCollimator responseFinite spatial resolutionBull's-eye mapCardiac SPECTActivity quantitationAttenuation correctionScatter correctionResolution correctionSpatial resolutionCollimator response correctionsSignal-to-noise ratioFrequency-distance principleImpact of scatteringLeft ventricleMonte Carlo simulationsCardiac phantomScatteringCarlo simulationsLV cavityAbsolute quantitationImproved contrastLV regionsProcessing schemeShould scatter be corrected in both transmission and emission data for accurate quantitation in cardiac SPET?
El Fakhri G, Buvat I, Almeida P, Bendriem B, Todd-Pokropek A, Benali H. Should scatter be corrected in both transmission and emission data for accurate quantitation in cardiac SPET? European Journal Of Nuclear Medicine And Molecular Imaging 2000, 27: 1356-1364. PMID: 11007518, DOI: 10.1007/s002590000304.Peer-Reviewed Original ResearchConceptsTransmission dataSingle-photon emission tomographyActivity distributionSignal-to-noise ratioCardiac single-photon emission tomographyAttenuation-corrected imagesAmount of scatterNarrow transmission windowHot compartmentActivity quantitationTransmission scanEmission dataEmission acquisitionTransmission windowReduced signal-to-noise ratioTransmission scatteringScatteringScattering componentPhantomQuantitative accuracyReduced scatteringAttenuating mediaReconstructed imagesLine sourceEmission
1999
Respective roles of scatter, attenuation, depth-dependent collimator response and finite spatial resolution in cardiac single-photon emission tomography quantitation: a Monte Carlo study
El Fakhri G, Buvat I, Pélégrini M, Benali H, Almeida P, Bendriem B, Todd-Pokropek A, Di Paola R. Respective roles of scatter, attenuation, depth-dependent collimator response and finite spatial resolution in cardiac single-photon emission tomography quantitation: a Monte Carlo study. European Journal Of Nuclear Medicine And Molecular Imaging 1999, 26: 437-446. PMID: 10382086, DOI: 10.1007/s002590050409.Peer-Reviewed Original ResearchConceptsDepth-dependent collimator responseCollimator responseMonte Carlo simulationsActivity underestimationSingle-photon emission tomographyCarlo simulationsSignal-to-noise ratioSpatial resolutionCardiac phantomFWHM spatial resolutionCardiac single-photon emission tomographyQuantitative accuracyAnthropomorphic cardiac phantomPhysical effectsInfluence of scatteringEffect of scatteringScatter countsFull-widthIncreased SNRPoor spatial resolutionScatteringMap homogeneityPhantomMonteImaging system