mr磁敏感伪影与射频屏蔽伪影的影响因素与抑制方法

《mr磁敏感伪影与射频屏蔽伪影的影响因素与抑制方法》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

1、兰州大学硕士学位论文anInvitroStudyFortheInfluenceingFactorsandInhibitingMethodsofMagneticSusceptibilityArtifact(MSA)DuringMRImaging．ABSTRACTObjectivethisstudywasfocusedontheinfluencingfactorssuchasmaterial，size，MRsequence，perameterandinhibitingmethodsofMagneticsusceptibilityarti

2、fact(MSA)duringMRimaging．Methods9screwswithdifferentmaterial(copper，titanium，stainlesssteel)andsizefixedinwaterphantomweretestedwithdifferentMRsequences(suchasspinecho，turboSE，gradientecho，shorttimeinversionrecovery，chemicalshiftselectivefatsuppression，SE．echo．planarim

3、aging)andparameters(suchasfieldofview，timeofecho，Matrix，slicethickness，flapangle，numberofacquisition，bandwidth，phase-frequencyencodingdirectionandsampleorientation)，theDiameterofartifact(DA)andvalueofArtifact—screwsizeratio(ASR)weremeasuredbySPSS13．0statisticsoftware．R

4、esults①Artifactsweremostmarkedinstainlesssteel，secondinCuandslightestinTi，statisticdifferencewastestified．ArtifactswerecharacteristicofgeometrydeformationandsignaldistortionwithSE，TSE，EPI．SE，STIRandCHESS-FSsequences，andsignallosswithGRE．ArtifactswithEPI．SEandGREweremuc

5、hworsethanthesewithSE，TSEandSTIR，significantdifferenceofartifactsbetweenSTIRandCHESS-FSwasalsotestified俨<0．001)．②Second，artifactswerelightenedmoreorlesswhenincreasedMatrix，flipangle，numberofacquisition(Naq)andbandwidth(Bw)，decreasedfieldofview(FOV)，slicethicknessandTEw

6、ereappliedandwhenlongaxisofsamplewasparalleltomainfieldorientation，however，somedifferenceofdiminishingamplitudeofASRwiththeseparameterswasdemonstrated，meanwhile，artifactswereslighteronphase—encodingdirectionthanthatonfrequency—encodingdirectionwithSEgroup，itwasreversed

7、withEPI．SEandnodifferencewithGRE(pairingttest，P<0．05)．ConclusionSusceptibilityartifactswereclearlyaffectedbyimplantmaterial，pulsesequencesandimagingparameters．MRartifactscanbeminimizedbychoosingTSE，STIRinsteadofEPI，GREandCHESS．FSsequencesandbyadoptingsmallvoxelsize，sho

8、rtTEandwidenedBW，it．5．兰州大学硕士学位论文isfeasibletoplacethelongaxisofimplantsparalleltomainfieldandtotransformfrequency-phas