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Author'sresponsetoreviewsTitle:Theascendingaorticimagequalityandthewholeaorticradiationdoseofhigh-pitchdual-sourceCTangiographyAuthors:YingLiu(yingyinglyly@126.
com)JianXu(xujian@fmmu.
edu.
cn)JianLi(xjyylj@yeah.
net)JingRen(jrenmm@126.
com)HongtaoLiu(liuhongtao@siemens.
com)JunqingXu(junqingxu@126.
com)MengqiWei(weimengqi2008@163.
com)YuewenHao(1982_edifier@163.
com)MinwenZheng(zhengmw2007@163.
com)Version:2Date:19November2013Author'sresponsetoreviews:seeoverDearEditor,Wethankthereviewersfortheirveryconstructivecomments.
Belowpleasefindourpoint-by-pointresponsestothereferees'comments.
Thankyouverymuchforyourconsideration.
Sincerelyyours,LiuYingReplytocommentsbyreviewer#1:Reviewer'sreportTitle:Theascendingaorticimagequalityandthewholeaorticradiationdoseofhigh-pitchdual-sourceCTangiographyVersion:1Date:29July2013Reviewer:MichaelLellReviewer'sreport:-MajorCompulsoryRevisions:JournalofCardiothoracicSurgeryMS:1644200371023407Theascendingaorticimagequalityandthewholeaorticradiationdoseofhigh-pitchdual-sourceCTangiographyTheauthorsreporttheirfindingscomparingconventionalpitchCTA(CP-CTA)withhighpitchCTA(HP-CTA)oftheaortain110patients.
-Generalcomments:1.
Thetopicisnotnew,thepaper"High-pitchelectrocardiogram-triggeredcomputedtomographyofthechest:initialresults.
LellM,HinkmannF,AndersK,etal.
InvestRadiol.
2009Nov;44(11):728-33"wasthefirstonthistopicandmayothersfollowed,forexample:Radiationdoseandimagequalityathigh-pitchCTangiographyoftheaorta:intraindividualandinterindividualcomparisonswithconventionalCTangiography.
ApfaltrerP,HannaEL,SchoepfUJ,SpearsJR,SchoenbergSO,FinkC,VliegenthartR.
AJRAmJRoentgenol.
2012Dec;199(6):1402-9.
Imagequality,contrastenhancement,andradiationdoseofECG-triggeredhigh-pitchCTversusnon-ECG-triggeredstandard-pitchCTofthethoracoabdominalaorta.
BolenMA,PopovicZB,TandonN,FlammSD,SchoenhagenP,HalliburtonSS.
AJRAmJRoentgenol.
2012Apr;198(4):931-8.
High-pitchdual-sourceCTangiographyofthewholeaortawithoutECGsynchronisation:initialexperience.
BeeresM,SchellB,MastragelopoulosA,HerrmannE,KerlJM,Gruber-RouhT,LeeC,SiebenhandlP,BodelleB,ZangosS,VoglTJ,JacobiV,BauerRW.
EurRadiol.
2012Jan;22(1):129-37…Response:Thereareseveralpapersonhigh-pitchCTAofaorta.
Ourpaperfocusesonthedifferencebetweenhigh-pitchCTAofaortaandconventionalCTAofaortawithoutECG-trigger.
Dr.
BeeresM,etalreportedonhigh-pitchdual-sourceCTangiographyofthewholeaortawithoutECG,however,theliteraturehadasmallnumberofcases.
Also,thereferencemAswas184,whichishigherthanours(110referencemAs).
Thanks.
2.
FromtheexistingliteratureitiswellknownthatCTAwithpitchvaluesupto1.
5andwithoutECGcorrelationisoftendegradedbypulsationartifactsattheaorticroot.
Theauthorsdidnottakethisintoconsiderationsettinguptheirstudy.
Response:Weagreewiththereviewerthathigh-pitchCTAscanwithoutECGisoftendegradedbypulsationartifactsattheaorticroot.
Weaddedthisissuetothediscussion,thanks.
3.
Thediscussiontopicofradiationexposureisrudimentaryandequivocal:HPMisreferredtoasa"low-dose"scanmode.
ThisiscorrectforcoronaryCTA(becausenoredundantdataisacquired),butnotforotherapplicationswhereallacquireddataisusedforimagereconstructionlikeaorticCTA.
ThereasonforlowerDLPandeff.
dosevaluesisinhomogeneousdosedistribution.
Forthatissuepleasereferto"Dual-sourcespiralCTwithpitchupto3.
2and75mstemporalresolution:imagereconstructionandassessmentofimagequality.
FlohrTGezal.
MedPhys.
2009Dec;36(12):5641-53"or"High-pitchspiralcomputedtomography:effectonimagequalityandradiationdoseinpediatricchestcomputedtomography.
LellMM,etal.
InvestRadiol.
2011Feb;46(2):116-23"Response:Thanks.
Wehavechanged"radiationexposure"to"radiationdose".
4.
Themanuscriptneedssomeprofoundcopyediting.
Response:Wehavetriedourbesttogetcopyeditingbetter.
Thanks.
5.
Theterm"Flashmode"shouldbeavoidedandtheterm"high-pitchCTA"or"high-pitchmode(HPM)"usedinstead.
Response:Wehavechanged"Flashmode"to"high-pitchCTA"or"high-pitchmode(HPM)"assuggested,thanks.
6.
Amajordrawbackisthattheclinicalrelevanceofthispaperisnotwellelucidated.
Response:Wehavedeclaredthisissueinthebackgroundandthediscussion.
Thanks.
Somespecificcomments:1.
Abstract:1.
1Background:incidenceofADshouldbegivenandmortalityandmorbidityrate.
Response:Wehaveaddedthisissuetothebackground,thanks.
1.
2Methodsandresults:groupwithECGcorrelatedconventionalpitchCTAisMissingResponse:Whenhigh-pitchCTAscanwithprospectiveECGtriggeringwasusedfordatacollectionatapresetperiodofcardiaccyclephase,thepatient'sheartrateneedstogetcontrolledwiththelimitoflessthan70beats/mininordertoobtainagoodimage.
Also,withECG-triggeredhigh-pitchhelicalCTscanofthethoracoabdominalaorta,thescanacquisitionofcardiaccyclephasecanonlybesetto60%RRinterval,whichisintrinsicdevicelimitations.
Underthiscondition,thepatientswithslowheartratecangetgoodimagequality,however,thepatientswithaorticdissectionareverydangerous,andtheyalwayshaveincreasedheartrate.
Mostofthemarenotsuitableforheartratecontrol,andthesedifficultpatientsarehardtocooperatewith.
Thus,inouropinion,high-pitchCTAscanwithprospectiveECGtriggeringisnotsuitableforthepatientswithurgentcardiovascularproblems.
ThesearethereasonswhywedidnothavethegroupsofconventionalpitchCTAwithECGandhigh-pitchCTAwithECG.
1.
3Conclusion:seecommentaboveonradiationexposureResponse:PleaseseeresponsetothecorrespondingcommentofGeneralCommentNo3.
2.
Introduction:Explainthereasonfornon-ECGtriggeredHPM.
CriticallyillpatientshaveECGleadsanyhow,soitwouldbeveryeasytotriggerthescan.
Response:PleaseseeresponsetothecorrespondingcommentofSpecificCommentNo1.
2.
Also,weaddedthisissuetotheintroductionofthemanuscript,thanks.
3.
Aim:"…hopingtoreduce"soundsstrange;it'stheauthorsaimtoreducedoseandartifacts.
Response:Wechanged"hoping"to"aiming"assuggested,thanks.
4.
Materials:4.
1groupwithECGcorrelatedconventionalpitchCTAismissingCTDataacquisition:Response:PleaseseeresponsetothecorrespondingcommentofSpecificCommentNo1.
2.
4.
24.
line370mgI/mL(Iodineismissing)Response:Thanks.
4.
3Whyusing0.
5sfortheCPMandnot0.
3or0.
28sResponse:BeforeinstallingthisflashCTscanner,thefastestrotationtimeofconventionalaorticCTscanwithourdepartmentaloldequipment(SiemensSensation16SliceCTandSiemensSensation64SliceCT)is0.
5s.
Wefoundthatitobviouslyaffectedtheimagequalityoftheascendingaorta.
InordertocomparethedataofthesethreeCTscanners,weextendedtousetherotationtimeof0.
5s.
4.
4WhichtubecurrentwasusedforCPMResponse:Thetubecurrentis110mAsinbothgroups,aswementionedinthepart"CTDataAcquisition"ofthemanuscript.
4.
5WhywascaudocranialscandirectionusedinoneprotocolandcraniocaudalintheotherResponse:Thecraniocaudalscandirectionisusedinbothgroup,aswementionedinthepart"CTDataAcquisition"ofthemanuscript.
4.
6IfAECwasusedthetubecurrentshouldbegiveninref.
mAsResponse:Thanks.
Wemodifiedthisinthepart"CTDataAcquisition"ofthemanuscriptassuggested.
5.
Postprocessing:5.
1Imagereconstructionisnotpartofpostprocessingandshouldbemovedtoanothersubheading;Response:Wechanged"postprocessing"to"PostprocessingandImageReconstrction".
5.
2B26isakerneldedicatedfor180°reconsImageevaluationshouldbebasedonMPR;MIPandVRTareoptional(pleaseremove"maximumintensityprojection(MIP),curvedplanarreformation(CPR),volumerenderingtechnique(VRT)andsoon.
"Whatdoes"soon"standforResponse:Weremovedthemassuggested.
5.
3Qualificationlevelofreadersshouldbeprovided.
Response:Theyareexperiencedattendingradiologists.
6.
1MotionartifactsanddifferencesinHU(attenuationprofiles)throughoutthecompleteaortashouldbegiven.
Response:MostofthereferencespresenttheCTenhancementvalues(Hu)ofaorticarchandiliacarterybifurcation.
AndwementionedtheCTenhancementvaluesinTable3andthepulsationartifactsofascendingaorticrootinthepart"Results"ofthemanuscript.
6.
2ROImeasurementsshouldbeperformedondifferentslicesperpatientandtheexactlocationshouldbegivenAreferencestandardismissing;Response:Firstofall,thedatawerecomparablebetweenthetwogroupswhenthemeasuresurfaceofROIinthetwogroupswasbothsettotheaorticarchandiliacarterybifurcation.
Moreover,theaortaisalongartery.
TheROImeasurementofaorticarchandiliacarterybifurcation,whichwastheupperendandlowerendoftheaortarespectively,maythoroughlydeclareaorticimaging.
6.
3StanfordAdissectionsaresurgicallesions,thereforeatleasttheintraoperativefindingsshouldbeprovided,echoorTEEwouldbeotheroptions.
Response:AlotofliteraturereportedthatthediagnosticaccuracyofaorticproblemswithCTAscansishigh.
Ourstudyfocusedontheadvantagesofhigh-pitchCTAscaninradiationdoseandimagequality,andwedidnotmentionechoorTEE.
Weaddedintraoperativefindingsinthe"PatientsandImageFindings"ofthe"Results".
6.
4Clinicaldataaremissing;exactindicationsforCTAandsymptomsofthepatients.
Response:Weaddedtheseissuestothepart"Patients"ofthe"Methods"assuggested.
7.
Results:7.
1NeedtobebetterstructuredResponse:Wehavestructuredthe"Results".
Thanks.
7.
2ImpactonclinicalmanagementResponse:ThesecondgenerationDSCTsystemisequippedwithahigh-pitchdataacquisitionmodewithpitchvaluesofupto3.
4byfillingthegapswiththedataacquiredwiththeseconddetectorsystem.
Thishighpitchacquisitionmodeisfast,reducingthescantimefortheentireaortatoonlyabout2secondsandallowingforlowradiationdose.
ThefastCTAscanspeedofthewholeaortawithouttheapplicationofECG-gatingisespeciallyimportantforthedifficultpatients,suchaspatientswithurgentcardiovascularproblems,restlesspatientsandpatientswhocannotholdtheirbreathforlong.
7.
3ImpactoncosteffectivenessResponse:High-pitchCTAofthethoracoabdominalaortaisveryfast,thusthecontrastdosagedecreased.
Also,Theimagequalitywithhigh-pitchCTAisgood,andthediagnosticaccuracyofaorticproblemsishigh,thusthepatientsavoidhavingotherexaminations.
7.
4Locationofentryandre-entryResponse:Theanatomiccoverageofthescanisfromthethoracicinletthroughthepubicsymphysis,aswementionedinthePart"CTDataAcquisition".
Therefore,thelocationofentrywasthoracicinlet.
Wedon'tthinktheprotocolhadre-entrylocation.
7.
5DissectionintocoronaryarteriesResponse:WeaddedthistothePart"PatientsandImageFindings"ofthe"Results".
7.
6Atablewithfinaldiagnosisineachgroupshouldbeprovided(numberofpatientswithStanfordA,B,aneurysm,aortitis,…,noaorticpathology)Response:PleaseseeTable1ofthemanuscript,thanks.
7.
7SurgicalfindingsResponse:Weaddedittothe"Results".
7.
8Otherimagingfindings(TEE)Response:PleaseseeresponsetothecorrespondingcommentofSpecificCommentNo6.
3.
7.
9p-valuesshouldbelimitedto0.
xxor<0.
001,t-valuescouldberemoved.
Response:Wemodifiedp-valuesandremovedt-valuesassuggested.
7.
10imagenoiseinHPMseemstobelowerthanCPM(table2);whyisthatso,pleaseexplainandvalidatethisfinding(forexamplewithphantommeasurements)Response:ThenumbersofimagenoiseinHPMdobelowerthanthoseinCPM(20.
4±5.
3vs22.
6±9.
2,28.
3±7.
6vs31.
8±12.
2).
However,theP-valuesare0.
12and0.
10,respectively.
Therefore,infact,therearenosignificantdifferenceintwogroups.
8.
Discussion:8.
1"However,wheninvolvingtheascendingaorta,typeIandtypeIIdissectionimaging,evenwith64slicesspiralCTandearlierDSCT,thepulsationartifactoftheroot-proximalascendinglevelcannotbeeliminated"thisisnotcorrect,itcanbeeliminatedevenwithsinglesourceCTifECGgatingortriggeringisused.
Response:PleaseseeresponsetothecorrespondingcommentofSpecificCommentNo1.
2.
8.
2PleasediscusswhynoECGcorrelationwasused(seeabove)"Inourstudy,becauseofthelowradiationdoseandthehighnoise,onlysomeopeningsofcoronaryarteriescouldbeclearlydisplayedintheFlashspiralgroup.
"ThemainreasonisthatnoECGcorrelationwasusedsee"High-pitchthoracicCTwithsimultaneousassessmentofcoronaryarteries:effectofheartrateandheartratevariabilityonimagequalityanddiagnosticaccuracy.
ScharfM,etal.
JACCCardiovascImaging.
2011Jun;4(6):602-9"forexample.
Response:PleaseseeresponsetothecorrespondingcommentofSpecificCommentNo1.
2.
8.
3PleasediscussthereasonsforlowerdoseinHPM(seereferencesabove):inhomogeneousdosedistributionononehandbutextendedoverscanningontheother…Response:Thepitch(tablefeedpergantryrotationdividedbycollimatedbeamwidth)canbeincreasedsubstantially,whilestillallowingimagereconstructionbecauseofdual-sourcegeometry.
Asaresultofthehighpitch,overlappingradiationexposureisavoided,thussubstantiallyreducingtheradiationdosetothepatient.
9.
Conclusion:theclinicalimpactshouldbeinthefocushere.
InapatientwithStanfordAdissection1or2mSvdonotsignificantlyaddtothepersonalrisk.
Response:Weaddedtheclinicalimpactintheconclusionassuggested.
10.
Financialaspectsneedtobedeclared:oneoftheauthorsisSiemensemployee.
Response:Thanks.
Wedeclaredthis.
11.
ReferencesneedtobeupdatedResponse:Weupdatedthereferencesassuggested.
12.
Tables:seeaboveResponse:Wemodifiedthetablesassuggestedabove,thanks.
13.
FiguresimagequalityokResponse:Thanks.
14.
Inordertodemonstratethehomogeneityofaorticenhancement,aCPRshouldbeprovideddisplayingthecompleteaorta–preferablywithaHUhistogramalongthecenterline.
Response:WeaddedCPRtoFigure1CandFigure2Cassuggested.
Levelofinterest:AnarticleoflimitedinterestQualityofwrittenEnglish:NeedssomelanguagecorrectionsbeforebeingpublishedStatisticalreview:No,themanuscriptdoesnotneedtobeseenbyastatistician.
Declarationofcompetinginterests:IdeclarethatIhavenocompetinginterestsReplytocommentsbyreviewer#2:Reviewer'sreportTitle:Theascendingaorticimagequalityandthewholeaorticradiationdoseofhigh-pitchdual-sourceCTangiographyVersion:1Date:19August2013Reviewer:WeiguoLiReviewer'sreport:Theauthorsreported110patientswithsuspectedaorticdissectionandotheraorticdisordersscannedwithconventionalandhigh-pitchdual-sourceCTscan,andprovedthatCTimagesacquiredwithhigh-pitchdual-sourceCTprotocolhavebetterimagequalityandlessradiationdosedeposition.
Thisisaveryinterestingpaper.
Oneconcernonthetechnicalaspectofthestudy:thepulsationartifactoftheaorticwallofascendingaortaisobviouslyrelatedtoheartrateofthepatient.
Howdoesheartrateaffectthehighpitchdual-sourceCTprotocolInotherwords,ECGgatedflash,forexample,canbeusedtoreducethemotionartifact,thoughapplyingECGgatingwillincreasepatientdose.
CanauthorsdiscusstherationaleofnotapplyingECGgatingIsthehigh-pitchmethodfreeoftheinfluenceofheatrateResponse:PleaseseeresponsetothecorrespondingcommentofSpecificCommentNo1.
2ofreviewer#1.
Levelofinterest:AnarticleofimportanceinitsfieldQualityofwrittenEnglish:AcceptableStatisticalreview:Yes,andIhaveassessedthestatisticsinmyreport.
Declarationofcompetinginterests:IdeclarethatIhavenocompetinginterests