measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion-weighted mrs at 3t dominik weidlich参考-匠人.pdf

该【measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion-weighted mrs at 3t dominik weidlich参考-匠人 】是由【金钏】上传分享，文档一共【13】页，该文档可以免费在线阅读，需要了解更多关于【measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion-weighted mrs at 3t dominik weidlich参考-匠人 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。:..Received:12September2018|Revised:21November2018|Accepted:11December2018DOI:‐weightedMRSat3TDominik?Weidlich1Julius?Honecker2Oliver?Gmach3Mingming?Wu1||||Rainer?Burgkart4Stefan?Ruschke1Daniela?Franz1BjoernH.?Menze5||||Thomas?Skurk2Hans?Hauner2Ulrich?Kulozik3DimitriosC.?Karampinos1|||1DepartmentofDiagnosticandInterventionalRadiology,?TechnicalUniversityofMunich,Munich,Germany2ElseKr?nerFreseniusCenterforNutritionalMedicine,?TechnicalUniversityofMunich,Munich,Germany3ChairforFoodandBioprocessEngineering,?TechnicalUniversityofMunich,Freising,Germany4ClinicofOrthopaedicSurgery,KlinikumrechtsderIsar,?TechnicalUniversityofMunich,Munich,GermanyputerScience,?TechnicalUniversityofMunich,Munich,GermanyCorrespondenceDominikWeidlich,DepartmentofPurpose:TheinvivoprobingofrestricteddiffusioneffectsinlargelipiddropletsonDiagnosticandInterventionalRadiology,aclinicalMRscannerremainsamajorchallengeduetotheneedforhighb‐valuesKlinikumrechtsderIsar,,,81675Munich,‐weightedMRS(DW‐MRS):dominik.******@:,Grant/,oil‐in‐wateremulsionswerepreparedandex-Number:grantagreementNo677661,ProFatMRI;PhilipsaminedusingDW‐MRS,-:-toms,agoodcorrelationbetweenthemeasureddropletsizesbyDW‐MRSandbylaserdeflection(R2=;P=)andmicroscopy(R2=;P<)meas-%(±(±)(P<).Conclusion:ThepresentedmethodswereabletoproberestricteddiffusioneffectsinlipiddropletsusingDW‐,adiposetissuemicrostructure,diffusionoffat,DW‐MRS,;1–13./journal/mrm?icResonanceinMedicine|1:..2||-studyofadiposetissueandectopiclipidsinbothhealthandtioneffectsonthedependenceoftheDWsignalonb‐,,brownadipocytesconsistofdropletswithadiameterbelow10μm,whereaswhiteadipo-,theadipocytesizehaslongbeenknowntore-,,-,(.,inin-par-tramyocellularlipids),themeasurementofadipocytesizeinisontothemeanfreepathdiffusionlengththesmallertheadipocytescontainingunilocularlipiddroplets(.,,thesensitizationofdiffusionadipocytesandbonemarrowadipocytes),andthedifferen-(brownadipocytes)fromlargeunilocularlipidPresently,DW‐MRSisyettobeappliedforthenoninva-droplets(whiteadipocytes).However,--Diffusion‐weighted(DW)-needforhighb‐valueandlongdiffusiontimeDW‐MRSandtionoftheADCwithincreasingdiffusiontimesduetodiffu-‐‐MRSataclinical3Tdiffusionpropertiesoflipidshasproventobemorechalleng--ordersofmagnitudelowerthanwaterduetothelargemolec-,-usingsimulations,wasvalidatedexperimentallyinwater–,-,plexityoffat2|METHODS(posedofmultiplefatpeaks)consti-tutesamajorchallengeintheacquisitionofDW‐|‐MRSisaversatiletooltomeasurethediffusionDiffusionrestrictionbarriersinanMRexperimentwillintro-,12Whenahighducedeviationsfromthemonoexponentialsignaldecayandab‐valueisappliedtofattytissues,DW‐,,ahighb‐valueDW‐urs16:∞2?1S(Δ,,G)2222dln=?2Gmm?2S0(Δ)m=12(1)2+exp(?2D(Δ?))?2exp(?2D)?2exp(?2DΔ)+exp(?2D(Δ+))2mmmm?2?22mD(mD):..WEIDLICHEtaL.|3whereSistheDWsignal,-densityandrelaxationeffects,?isthediffusiontime,δispensateforeddy‐currenteffects(halfoftheaverageswereac-thediffusiongradientlength,Gisthegradientstrength,γisquiredwithpositiveandtheotherhalfwithnegativepolarity).icmoment,disthediameterofthesphericalThepreprocessingofthespectrawasbasedonacustom‐restrictionbarrier,Disthefreediffusionconstant,andαmarebuiltprocessingpipelineimplementedin‐houseinMATLABtherootsobtainedbythefollowingdifferentialequationof(MathWorks,Natick,MA).17ThepipelineincludedzeroorderBesselfunctions:phasecorrectionofeachb‐valueandpolarityandGaussianmJ3m?Jm=0(2)takingthecross‐correlationwiththefirstaverageofeachb‐222222valueandpolarityandshiftingthespectrumoftheremain-ingaveragesinfrequencydomainuntilamaximumoftheTheequationforsignalattenuation(Equation1)isnotcross‐-onlyafunctionoftheb‐,thesizeofthedif--fusionrestrictingbarrierscanbeextractedbasedontheDWfectoftheoutlierremovalisfurtherdiscussedinSupportingsignalatdifferentdiffusiontimesanddiffusionweightingsasInformationFigureS6inthesupplementarymaterial,|DW‐:;,Tomeasurethediffusionpropertiesoflipids,abipolarDWβ‐,α‐,α‐carboxylatSTEAMMRS(Figure1),,,-gradientsinall3axesaddedafterthefirstandthirdRFpulseableduetothestrongdiffusion‐--ylenepeakarea()wasusedtoestimatethelipidtionwasmaximizedforagivenTEandthestrengthofthedropletsize,becausethedifferentfatpeaks,ingeneral,differdiffusionweightinggradientswasadjustedtoachievecertainindiffusioncoefficient6,‐‐|~3000throotbecauseafter-,thenon‐:TEΔ?2TMS0(Δ)=?exp?=?exp?(3)T1T1TheTEoftheSTEAMsequencewaskeptconstant;there-fore,:Thethree90°sliceexperimentaldataacrossdiffusiongradientstrengths,diffu-,anddiffusiontimesSexpwerethusdiffusiongradients(incolor)‐parametereddycurrenteffects,thediffusion‐weightinggradientsalternateoverfitwithunknownsthefreediffusionconstantD,thediametertheacquiredaveragesbetweenpositive(orange)andnegative(blue)ofdiffusionrestrictionbarrierd,theT1relaxationconstant,polarityandtheoverallsignalρ::..4|WEIDLICHEtaL.scanningparameters:DWSTEAMMRSwithvolumeofin-TMterest:(15mm)3,TE:60ms,δ=28ms,TR:1800ms,4096argminS(Δ,,G,T1)??exp??Sexp(4)D,d,T1,T1points,spectralwidth:5000Hz,8phasecycles,16averagesperb‐value(halfoftheaverageswithpositiveandtheotherhalfwithnegativepolarity),1start‐upcycle,b‐values:10,000–20,000–40,000–60,000s/mm2,14:|Numericalsimulationsvoxellocation,mixingtimesof300,400,500,600,and700Toevaluatethenoisecharacteristicsofthefitting,-,-,‐,themeasure-‐:TM:between300msand700mspeakareawasestimatedindividuallyforeachaverageandth