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LeftVentricularDyssynchronyParametersMeasuredbyPhaseAnalysisofPost-stressandRestingGatedSPECTMyocardialPerfusionImagingYanliZhou,TheFirstAffiliatedHospitalofNanjingMedicalUniversityDianfuLi,TheFirstAffiliatedHospitalofNanjingMedicalUniversityJianlinFeng,TheFirstAffiliatedHospitalofNanjingMedicalUniversityDonglanYuan,TheFirstAffiliatedHospitalofNanjingMedicalUniversityZenicPatel,EmoryUniversityKejiangCao,TheFirstAffiliatedHospitalofNanjingMedicalUniversityJiChen,EmoryUniversityJournalTitle:WorldJournalofNuclearMedicineVolume:Volume12,Number1Publisher:MedknowPublications|2013,Pages3-7TypeofWork:Article|FinalPublisherPDFPublisherDOI:10.
4103/1450-1147.
113931PermanentURL:https://pid.
emory.
edu/ark:/25593/s2cr3Finalpublishedversion:http://dx.
doi.
org/10.
4103/1450-1147.
113931Copyrightinformation:WorldJournalofNuclearMedicineAccessedMarch16,20212:41PMEDTWorldJournalofNuclearMedicine/Vol12/Issue1/January20133IntroductionPhaseanalysishasbeendevelopedtoassessleftventricular(LV)dyssynchronybasedongatedsinglephotonemissioncomputedtomography(SPECT)myocardialperfusionimaging(MPI).
[1]IthasbeenshownthattheLVdyssynchronyparameters(phasestandarddeviation(PSD)andphasehistogrambandwidth(PHB))measuredbyphaseanalysiscorrelatewellwiththosemeasuredbytissueDopplerimaging,[24]andpredictedresponsetocardiacresynchronizationtherapy(CRT)inheartfailure(HF)patients.
[5]Recently,phaseanalysishasshowntobeabletoidentifythesiteoflatestmechanicalactivationastheoptimalLVpacingleadposition.
[6]Intheabovevalidationstudies,allgatedSPECTimageswereacquiredusingrestingTechnetium99m(Tc99m)gatedSPECTMPIprotocols.
Inpractice,mostoftheTc99mMIBISPECTMPIscansareperformedusingsamedayresting/stressprotocols,wheretherestingdataareacquiredusingarelativelylowdoseascomparedtothestressdata,andmanycentersonlyacquiregatedSPECTdataatstress.
Presumably,thehighcountgatedSPECTdataacquiredpoststresscanprovidebetterquantificationofLVfunction.
However,ithasbeenshownthatinpatientswithanearliermyocardialinfarction,LVfunctionpoststressmightnotrepresentthetruerestingLVfunction.
[7]Consequently,thisstudysuggestedthestratificationofpatientsbeforestartinggatedSPECTMPI,meaninginpatientswithanearliermyocardialinfarction,thegatedacquisitionshouldbeperformedduringtherestingstudy.
Inanotherstudy,poststressLVejectionfraction(LVEF)reducedandendsystolicLeftVentricularDyssynchronyParametersMeasuredbyPhaseAnalysisofPoststressandRestingGatedSPECTMyocardialPerfusionImagingYanliZhou1,DianfuLi1,2,JianlinFeng2,DonglanYuan2,ZenicPatel3,KejiangCao1,JiChen31DepartmentsofCardiology,2NuclearMedicine,TheFirstAffiliatedHospitalofNanjingMedicalUniversity,Nanjing,Jiangsu,China,3DepartmentofRadiology,EmoryUniversity,Atlanta,GA,USAAbstractPhaseanalysishasbeenvalidatedtomeasureleftventricular(LV)dyssynchronyfromrestinggatedSPECTmyocardialperfusionimaging(MPI).
In1dayrest/stressprotocols,oftenonlypoststressgateddataareacquired.
ThepurposeofthisstudywastodeterminewhetherLVdyssynchronyparametersmeasuredatpoststresssignificantlydifferfromthosemeasuredatrest.
Sixtynormalsubjects,40patientswithstressinducedischemiabutnormalLVfunction,and29patientswithLVdysfunctionwereincludedinthisstudy.
Allpatientswerescannedusinga2dayTechnetium99msestamibi(MIBI)MPIprotocol,wheregatedSPECTdatawereacquiredat60minpostinjectionoftheradiotracer.
LVdyssynchronyparametersatpoststressandatrestwerecalculatedandcomparedusingpairedttest.
TherewerenosignificantdifferencesintheLVdyssynchronyparametersbetweenpoststressandrestinginallcohorts.
NopatientshoweddifferencesintheLVdyssynchronyparametersbetweenthepoststressandrestingscanssignificantlygreaterthanthereportedvariationsintheseparametersbetweenserialrestingscans.
Therewasnosignificantdifferenceindyssynchronyparametersmeasuredatrestand60minafterstressonMPIgatedimages.
Keywords:Leftventriculardyssynchrony,myocardialperfusionimaging,phaseanalysisAddressforcorrespondence:Dr.
DianfuLi,DepartmentofCardiology,TheFirstAffiliatedHospitalofNanjingMedicalUniversity,300GuangzhouRd,Nanjing,Jiangsu210029,China.
Email:lidianfu@gmail.
comOriginalArticleAccessthisarticleonlineQuickResponseCode:Website:www.
wjnm.
orgDOI:10.
4103/1450-1147.
1139314WorldJournalofNuclearMedicine/Vol12/Issue1/January2013volumeandenddiastolicvolumeincreasedinpatientswithstressinducedischemia.
[8]However,theeffectofischemiaonthedifferencebetweenpoststressandrestingLVfunctionmeasurementswasmodestandrarelyexceededtheconfidencelimitsinnormalpatientsundergoing2dayprotocols.
[9]Thereisarecentstudyenrolling20patientswithreversibleperfusiondefectsinvolving>10%oftheLVmyocardiumand20normalsubjectstoshowthattherewasnosignificantchangefromresttostressintheLVdyssynchronyparametersbetweenthetwogroups.
[10]ItisimportanttonotethatallofthesubjectsinthisstudyhadnormalLVEF.
TheimpactofstressonLVdyssynchronyparameterswasnotevaluatedinpatientswithLVdysfunction.
ThepurposeofthisstudywastodeterminewhetherLVdyssynchronyparameters(PSDandPHB)measuredatpoststresssignificantlydifferfromthosemeasuredatrestinnormalsubjects,patientswithstressinducedischemiabutnormalLVEF,andpatientswithLVdysfunction.
MaterialsandMethodsPatientsThestudyretrospectivelyanalyzedgatedSPECTMPIdataacquiredfromJuly2008toJanuary2010.
Sixtynormalsubjects(30underwentexercisestressand30underwentadenosinestress),40patientswithstressinducedischemiabutnormalLVfunction(LVEF>50%,20underwentexercisestressand20underwentadenosinestress),and29patientswithLVdysfunction(LVEF<50%,19underwentexercisestressand10underwentadenosinestress)wereincludedinthisstudy.
Table1summarizesthecharacteristicsofthethreecohorts.
Stressinducedischemiawasconsideredinthepresenceofreversiblemyocardialperfusiondefectatstress.
Amongthe29patientswithLVdysfunction,14hadischemiccardiomyopathy(including10patientswithmyocardialinfarction)and15patientshadnonischemiccardiomyopathy.
Thestudyprotocolwasapprovedbytheinstitutionalreviewboard(IRB).
AcquisitionandprocessingA2dayMIBISPECTMPIprotocolwasusedinthisstudy.
PatientswhohadexercisestressunderwentasymptomlimitedtreadmilltestusingstandardBruceprotocol.
MIBIwasintravenouslyinjectedwhena≥85%heartratewasachieved.
Exercisewascontinuedattheworkloadfor1.
5-2.
0minwhenpossible.
Patientswhohadadenosinestresswereinfusedwithadenosineat140g/kg/minfor5minandMIBIwasinjectedattheendofthesecondminute.
Tc99mSestamibidosesrangedfrom25to30mCidependingonthepatients'weightorbodymassindices.
APhilipsCardioMDsystem(PhilipsMedicalSystems,Milpitas,CA,USA)wasusedtoacquireallpoststressandrestingscanswith20%energywindowsaround140keV.
Atotalof64projections(24sec/projection,totalacquisitiontimeof14min)wereobtainedovera180°circularorbit.
ThegatedSPECTdatawereacquiredaseightframespercardiaccycle.
Datawerestoredina64–64matrixwith6.
4mm/pixel.
AllofthegatedSPECTdatawerereconstructedusingamanufacturerprovidedfilteredbackprojectionprogram(AutoSPECTPlus,PhilipsMedicalSystems).
AllreconstructeddatawerereorientedtogenerategatedshortaxisimagesandthensubmittedtophaseanalysistocalculatePSDandPHB.
[1]Thepoststressandrestingimageswereprocessedsidebysidebyanexperiencedtechnologist,whowasblindedfromthisresearchproject.
StatisticalanalysisPairedttest(twotailed)andBland–AltmanplotwereusedtocomparethepoststressandrestingPSDandPHBinthethreecohorts,respectively.
AP<0.
05wasconsideredstatisticallysignificant.
ResultsTable2showstheLVdyssynchronyparametersinthethreecohorts.
Innormalsubjects,althoughitshowedatrendthatLVdyssynchronyparametersacquiredfromstressscansweresmallerthanthosefromrestingTable1:PatientcharacteristicsNormalsubjects(n=60)Patientswithischemia(n=40)PatientswithLVdysfunction(n=29)Age(years)60.
3±18.
360.
9±10.
261.
8±9.
5Male(%)5567.
582.
5Diabetesmellitus(%)8.
917.
512.
5Hypertension(%)456357.
5MI/nonMI(%)NA7.
5/92.
534.
5/65.
5Ischemic/nonischemic(%)NANA48.
2/52.
8QRSduration(msec)100±18.
7101.
5±20.
9102.
5±20.
9SSSNA6.
1±3.
913±12SDSNA4±2.
91.
9±2.
1MI:Myocardialinfarction;SSS:Summedstressscore;SDS:SummeddifferencescoreWorldJournalofNuclearMedicine/Vol12/Issue1/January20135scans,thedifferenceswerenotsignificant.
Figure1a-cshowstheBland–AltmanplotsthatcomparedtheLVdyssynchronyparametersbetweenthepoststressandrestingscansinthethreecohorts.
ThemeandifferencesintheLVdyssynchronyparameterswereverysmall,indicatingtherewerenosystemicdifferencesintheseparametersbetweenthepoststressandrestingscans.
TherewerenooutliersthatshowedclinicallyimportantdifferencesintheLVdyssynchronyparametersbetweenthepoststressandrestingscans,indicatingthetwoscansyieldedequivalentresults.
Figure2aandbshowstwoexamplepatientswithanteriorandinferiorischemiapoststress,respectively.
BothpatientshadcomparableLVsynchronyatpoststressandatrest.
Figure3showsanexamplepatientwithsevereLVdysfunction(LVEF=24%)andmyocardialinfarction(summedstressscore=33).
Eventhoughseverereductioninperfusionuptakeintheinfarctregionmightimpactthephasemeasurement,theglobalLVdyssynchronyparameterswerenotsignificantlydifferentbetweenthepoststressandrestingscans,indicatingthatphaseanalysiswasarobusttooltomeasureLVdyssynchronyinpatientswithsevereLVdysfunctionandmyocardialinfarction.
DiscussionThisstudycomparedLVdyssynchronyparametersmeasuredbyphaseanalysisofgatedSPECTMPIbetweenpoststress(eitheradenosineorexercise)andrestingscans.
Nosignificantdifferencesintheseparameterswereobservedinnormalsubjects,patientswithstressinducedischemiabutnormalLVfunction,andpatientswithLVdysfunction.
AsthemajorityofclinicalMPIdataareacquiredusing1dayTc99mprotocol,whereusuallygatedSPECTdataareacquiredonlyatpoststress,thisfindingsupportstheapplicationTable2:PoststressandrestingLVfunctionparametersNormalsubjects(n=60)Patientswithischemia(n=40)PatientswithLVdysfunction(n=29)StressRestStressRestStressRestPSDMean9.
39.
38.
98.
828.
529.
9SD2.
01.
92.
92.
417.
118.
8Pvalue0.
890.
820.
05PHBMean28.
529.
528.
428.
895.
699.
9SD5.
95.
78.
38.
370.
474.
0Pvalue0.
230.
740.
06EFMean76.
176.
261.
564.
833.
535.
4SD6.
46.
49.
77.
510.
110.
9Pvalue0.
830.
0040.
12PSD:Phasestandarddeviation;PHB:Phasehistogrambandwidth;SD:Standarddeviation;LV:LeftventricularFigure1:Bland-Altmanplotsforcomparisonsofthepost-stressandrestingLVdyssynchronyparametersinthe(a)normalsubjects,(b)patientswithstress-inducedischemiabutnormalLVfunction,and(c)patientswithLVdysfunctioncba6WorldJournalofNuclearMedicine/Vol12/Issue1/January2013ofphaseanalysistopoststressTc99mgatedMIBISPECTMPIdatatomeasureLVdyssynchrony,whichisequivalenttothatmeasuredatrest.
StressinducedischemiaisassociatedwithpoststressreductioninLVEFandincreasedpoststressEDVandESV.
[11]StressinducedsevereischemiamayleadtomyocardialstunningandtransientLVdilation,andpossiblyLVdyssynchrony.
AfewstudiesshowedthatphysicaleffortmightfurtherincreaseLVdyssynchronyinpatientswithHFassessedbyechocardiographyduringexercise.
[1214]However,arecentstudyreportedthatevenalargereversibleperfusiondefectdoesnotaltertheindicesofmechanicaldyssynchronybyphaseanalysisinpatientswithcoronaryarterydiseaseandnormalLVEF,whenallpoststressdatawereacquired60minpostinjectionofTc99mSestamibi.
[10]Thisstudyconfirmedthatfinding,andindicatedthatthepoststressLVdyssynchronywasequivalenttothatattherestingstateinpatientswithLVdysfunction.
ForTc99mSestamibi,thepoststressimageacquisitionminimumdelayis15-20minforexercisestress,45-60minforresting,and60minforpharmacologicstress,[15]inordertoavoidtheinfluenceofliverandgutuptake.
Weuniformlyacquirethestressimaging60minaftertracerinjection.
Asweallknow,theparametersofthewallmotionanddyssynchronyarederivedfromthegatedimagesthatareacquiredatthetimeofimaging,notatthetimethetracerinjection.
So,thetimingofacquisitionmayaffectthefunctionanddyssynchronyparameters.
Therearetwolimitationsofthisstudy.
First,thereareonly14ischemicand15nonischemicHFpatientsinthisstudy,whichmaysuggestlimitedstatisticalpower.
Secondly,toclarifythedifferenceofLVdyssynchronyparametersbetweenthepoststressandrestingscans,differentstagepostinjectionofTc99mSestamibiwillbeobservedinourfurtherstudy.
ConclusionTheLVdyssynchronyparametersmeasuredat60minafterstressdidnotsignificantlydifferfromthosemeasuredatrestinnormalsubjects,patientswithstressinducedischemiabutnormalLVfunction,andpatientswithLVdysfunction,ina2dayTc99mMPIprotocol.
PhaseanalysiscanbeappliedtopoststressTc99mgatedSPECTMPIdatatomeasureLVdyssynchrony,whichisequivalenttothatmeasuredatrest.
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Onewithadenosinestressin(a)andtheotherwithexercisestressin(b).
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pdf[Lastaccessedon2013Jun02].
Howtocitethisarticle:ZhouY,LiD,FengJ,YuanD,PatelZ,CaoK,ChenJ.
LeftVentricularDyssynchronyParametersMeasuredbyPhaseAnalysisofPost-stressandRestingGatedSPECTMyocardialPerfusionImaging.
WorldJNuclMed2013;12:3-7.
SourceofSupport:ThisstudywassupportedinpartbythePublicHealthSupportProgramofJiangsuProvince,CHINA(ZX07200907)andbyanNIH-fundedresearchproject(1R01HL094438-01A1,PI:JiChen,PhD).
ThetermsofthisarrangementhavebeenreviewedandapprovedbyEmoryUniversityinaccordancewithitsconflict-of-interestpractice.
ConflictofInterest:Nonedeclared.
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