MRI技术应用：胸部和全腹部.ppt

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1、胸部和全腹部门控(Gating)人体许多部位的器官和组织都会或多或少地受呼吸.液体流动.脉搏和心跳的影响，所以在做相应部位检查的时候为了采集相对静止的图像，人们采取了一些措施，一般的方法为增加预饱和脉冲序列，其中目前主要的方法是利用“门控”。类型主要为：呼吸触发.周围脉搏和心电门控。什么是门控？InMagneticResonanceImagingItisadevicetosynchronizeMRdatacollectionwiththephysiologicalmotionsofthepatientItsign

2、ificantlyreducesmotion-relatedartifactsduetoRespirationFlowCardiacMotionOverviewTypesofGatingRespiratoryTriggeringPPGGatingCardiacGatingRespiratoryTriggeringTypesofGatingWhatisitusedfor?Toreduceartifactscausedbyrespiratorymotionorwhenapatientisunabletoperform

3、abreath-holdWhereisitused?Mostusedintheabdomentohelpproduceclear,artifact-freeimagesoftheanatomicalstructuresintheabdomenWhatisneeded?RespiratorybellowandrespiratorygatinghardwareHowdoesitdoit?Bysynchronizingdatacollectionofthesequencetothepatient’srespirator

4、ymotion.RespiratoryTriggeringTypesofGatingHowdoesitdoit?Bysynchronizingdatacollectionofthesequencetothepatient’srespiratorymotion.Changesinthepatient’schestcircumferenceareconvertedtoelectronicsignalandrelatedtotheMRImagingsystemProperplacementofthebellowsisr

5、equiredacrossthetrunkofthepatientwherethebreathingismostevident.Theyshouldbeplacetautacrossthepatient.AvoidstretchingofthebellowsInstructpatienttobreathnormal…thisinsuresamostaccuratewaveformRespiratoryintervaltypicallyrangesfrom400ms-15000msforonerespiratory

6、cycle.RespiratoryTriggeringRespiratoryTriggeringNextTypesofGatingRespiratoryTriggeringPPGGatingCardiacGatingPPGWhatisisusedfor?ToreduceartifactscausedbyCSFmotionorwhenCINEimagingwithbettercoverageofdiastoleisdesiredWhereisitused?Cervical&ThoracicSpineWhatisne

7、eded?Photoplethysmography(PPG)peripheralpulsemonitoryandhardwareHowdoesitwork?ThepatientspulsewilltriggerdataacquisitionandsynchronizeimagecollectiontothepatientspulsePeripheralPulseGatingPeripheralPulseGatingDichroticNotchOccursattheendofsystole,andthebeginn

8、ingofdiastolewhentheaorticvalvecloses.Theaortacontracts,causingflowintothecoronariesandaslightincreaseinperipheralflowNextTypesofGatingRespiratoryTriggeringPPGGatingCardiacGatingCardiacGa