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275200810ChineseJournalofBiomedicalEngineeringVol.27No.5October2008:2008201220,:2008206220:((50337020);(2006BAI03A00)3E2mail:hxwang@tju.edu.cn1,213111(,300072)2(,300222):(EIT),,,,,;,,,COMSOL,,,,:;;;;LungFunctionalImagingBasedonMedicalElectricalImpedanceTomographyCHENXiao2Yan1,2WANGHua2Xiang13SHIXiao2Lei1FANWen2Ru11(SchoolofElectricalandEngineering&Automation,TianjinUniversity,Tianjin300072)2(SchoolofElectricalInformationandAutomation,TianjinUniversityofScienceandTechnology,Tianjin300222)Abstract:Anewimagereconstructedalgorithmwaspresentedforthemedicalelectricalimpedancetomography(EIT).Firsttheadaptivemulti2gridalgorithmwasemployedbywhichthesequenceofcomputationalgridswassuccessivelyrefinedthroughtheposteriorerrorandtheadaptivegridsrefinement,thelungventilationwasimagedconsideringthefieldascircle.ThenthesensitivitymatrixwassolvedbycommercialsimulationsoftwareCOMSOLconsideringthestructureandresistivityoflung,thepriorinformationwasadoptedtoreconstructthelungconductivitydistribution.Onthelungventilationimagingsystem,twostepswereavailabletoreconstructthefunctionalrespirationprocessimageinreal2time.Theimagesindicatedthatahigheraccuracysolutionoftheforwardequationandthehigherspatialresolutionofimagescouldbeachieved.Keywords:medicalelectricalimpedancetomography(EIT);inverseproblem;imagereconstruct;lungfunctionalimaging;priorinformationR318A025828021(2008)0520663206(EIT),(5mA),,(),,,P[1-3],EIT:,;,EIT[4],[5],,,E1T[6][729],EITCTMRI,,EITEIT[10],:(1),,,,;(2),COMSOL,,,,1,,,,,,,,,,[11],Molinari[12],SoleimaniandPowell[13],,,,,,,,,111,,,,,,[14],,(1),kk,x+dxxk=||2dk=1,2,,m(1),,m(2)k,k,k=99n+-99n-dsk=1,2,,m(2),nkk,,,Ax=b(3),A(Jacobian),;b;x1V,r=b-Ax,,,,x+dxx,xx+dx,r,,1VFig.1Vcyclemultigridalgorithm,9571868,21122466272Fig.2AdaptivemultigridrefinementEIT,[15],,,,2EIT[16],2,(),()=U-U()2+2L(-3)2(4),U,U(),L,,3,i+1=i+(JTiJi+2LTL)-1[JTi(U-U(i))-2LTL(i-3)](5)Rk=|r|2dk=1,2,,m(6):,;,,(6),2,,L=I,;L=D1,L=D2(D1D2),,[17]EIT,211COMSOLCT(GEMedicalSystem16CT),CT,3;COMSOL,,4,,,3CTFig.3ScanningphotoofvolunteerbyGEMedicalSystem4Fig.4Simulatedthoraxmodel,1[18]1Tab.1Conductivitiesofissueswithinthorax(1Pm)0.670.0060.0420.1380.0375665:,COMSOL,,5,,6,8(a)(e);(f)(i)Fig.8Imagesoflungventilationonavolunteer.(a)(e)theinspiration;(f)(i)theexpiration5Fig.5RefinedthoraxmodelusingComsol3,16,71mA500kHz6Fig.6Simplifiedrefinedgrids7Fig.7Laboratorystudyoflungventilationonavolunteer66627,,,8,(a)(e),(f)(i)9[19221],(a)(e),(f)(i)9(a)(e);(f)(i)Fig.9Visualizationofrespirationinonecycleimagedbyconjugategradientwithpriorinformation.(a)(e)theinspiration;(f)(i)theexpiration,,,,,4EIT,,,COMSOL,,,,,10Fig.10ThecharacteristicpixelsofinteriorthoraxEIT(10),7665:11Fig.11Thecharacteristiccurveswithinlungsandheart(11),,,,,,,,COMSOL,,,TJUEITII,[1]HerdersonRP,WebsterJG.Animpedancecameraforspatiallyspecificmeasurementsofthethorax[J].IEEETransBiomedEng,1978,25:250-254.[2]BenabidAL,BalmeL,PersatJC,etal.Electricalimpedancebrainscanner:principlesandpreliminaryresultsofsimulation[J].TITJLifeSci,1978,8:59-68.[3]BrownB,SeagarA.TheSheffielddatacollectionsystem[J].ClinicalPhysicsandPhysiologicalMeasurements,1987,8:91-97.[4]SmitHJ.PulmonaryvascularresponsestohypoxiaandhyperoxiainhealthyvolunteersandCOPDpatientsmeasuredbyelectricalimpedancetomography[J].Chest,2003,123(6):1803-1809.[5]HolderDS,TempleAJ.EffectivenessoftheSheffieldEITsystemindistinguishpatientswithpulmonarypathologyfromaseriesofnormalsubject[A].In:HolderDSeds.ClinicalandPhysiologicalApplicationsofElectricalImpedanceTomography[M].London:UniversityCollegeLondonPress,1993.277-298.[6]BooneKG,BarberDC,BrownDC.ImagingwithelectricityreviewoftheEuropeanconcertedactiononimpedancetomography[J].JournalofMedicalEngineering&Technology,1997,21(6):201-232.[7]McArdleFJ,BrownBH,PearseRG,etal.Theeffectiveoftheskulloflow2birthweightneonatesonappliedpotentialtomographyimagingofcentrallisedresistivitychanges[J].ClinPhysPhysiolMeas,1988,9Suppl:A55-A60.[8]NoordegraafV.Validityandreproducibilityofelectricalimpedancetomographyformeasurementofcalfbloodflowinhealthysubjects[J].MedBiolEngComput,1997,25(2):107-112.[9]McArdleFJ,SuggettAJ,BrownBH,etal.Anassessmentofdynamicimagesbyappliedpotentialtomographyformonitoringpulmonaryperfusion[J].ClinPhysPhysiolMeas,1988,9SupplA:91-97.[10]BrownBH.ElectricalImpedanceTomography(EIT):areview[J].MedEngTechnol,2003,27(3):97-108.[11]MolinariM,BlottBH,CoxSJ,etal.Optimalimagingwithadaptivemeshrefinementinelectricalimpedancetomography[J].PhysiolMeas,2002,23:121-128.[12]MolinariM.Highfidelityimaginginelectricalimpedancetomography[D],PhDThesis,UniversityofSouthampton,2003.[13]ManuchehrSolemani,CatherinePowell,NickPolydrrides.ImprovingtheforwardsolverforthecompleteelectrodemodelinEITusingAlgebericmultigrid[J],IEEETrans.MedicalImaging,2005,24:577-583.[14]W.Briggs,Multigridtutorial[M],SIAM,Philadelphia,1987.[15]KauppinenP,HyttinenJ,MalmivuoJ.Sensitivitydistributionsimulationsofimpedancetomographyelectrodecombinations[A].In:BEM&NFSIConferenceProceedings[C].2005:344-347.[16]VauhkonenM,LionheartWRB,HeikkinenLM,etal.AMATLABpackagefor