Separation of Cellular and BOLD Contributions to T2

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1、FULLPAPERMagneticResonanceinMedicine00:00–00(2015)SeparationofCellularandBOLDContributionstoT2*SignalRelaxationXialingUlrichandDmitriyA.Yablonskiy*0R2¼R2þR2:[1]Purpose:ThedevelopmentofareliableclinicaltechniqueforquantitativemeasurementsoftheparametersdefiningtheInotherw

2、ords,theparameterR2representstheGREBOLDeffect,i.e.,oxygenextractionfraction(OEF),anddeoxy-signaldecayexpectedintheabsenceoftheBOLDgenatedcerebralbloodvolume,dCBV,isneededtostudyeffect.OneshouldkeepinmindthattheparameterR2brainfunctioninhealthanddisease.Hereinweproposesuch

3、inEq.[1],thatwecall“cellularcontribution”totheatechniquethatisbasedonawidelyavailablegradientR2*,generallydoesnotrepresentirreversible(withrecalledecho(GRE)MRI.respecttothespinecho)partoftheMRIsignaltrans-TheoryandMethods:OurmethodisbasedonGREwithmul-verserelaxation.Thisw

4、ouldonlybethecaseforasin-tipleechoesandamodelofsignaldecay(Yablonskiy,MRMglecompartmenttissueinthestaticdephasingregime1998)thattakesintoaccountmicroscopiccellular(R2),meso-(2).Foramulticompartmenttissue,Eq.[1]shouldscopic(BOLD),andmacroscopic(backgroundfieldgradients)0be

5、writtenintheformofR2¼R2þR2;however,incontributionstotheGREsignaldecaywithadditionalaccount-cingforphysiologicfluctuations.thismanuscriptweareusingtraditionalnotations,asResults:Using3TeslaMRI,wegeneratehighresolutionquan-definedinEq.[1](seefurthercommentsintheDiscus-tit

6、ativemapsofR2*,R2,R20,andtissueconcentrationofsionsection).SeparatingtheMRIsignaldecayduetodeoxyhemoglobin,thelatterprovidingaquantitativeversionoftheBOLDeffect,thatisR20,fromR2*,couldprovideSWI.OurresultsforOEFanddCBVingraymatterareinaimportantinformationontissuemetaboli

7、cpropertiesreasonableagreementwiththeliteraturedata.whichisimportantforunderstandingnormalhumanConclusion:Theproposedapproachallowsgeneratinghighbrainoperation(3)aswellasthepathophysiologyofresolutionmapsofhemodynamicparametersusingclinicalneurologicaldisorderssuchasstrok

8、e(4),Alzheimer’sMRI.Thetechniquecanbeappliedtostudysuchtissuesasdisease(5–7),Huntington’sdisease