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PictorialReviewofUrinaryTractObstructioninTc-99mMAG3Renograms withDiureticKushal Joshi,UniversityHospitalsofLeicester
Tauseef Ashraf,PilgrimHospital,Boston
MAG3Renogram
• Tc-99mMAG3renograms arecommonlyusedtoassessrenaloutflowtractobstruction.
• Theradiopharmaceutical(Tc-99mMAG3)isadministeredintravenously.
• Itsarrivalintothekidneysandexcretionismonitored.• Timeactivitycurvesprovidegraphicalrepresentationofrenal
uptakeandexcretion.Relativerenalfunctioncanalsobequantified.
• Postdiuresisimaging,afteradministrationoffurosemide,candistinguishbetweencompleteobstruction,partialobstructionordilatedbutnon-obstructedsystems.
NormalRenogram:3Phases
1. FlowPhase- Sharpupslope- Slowupslopesuggestreducedperfusion
2. CorticalPhase- Peakoftherenogram (1-3minutes)- Decreasedrenalfunctionproducesdelayedcorticaluptake
3. ClearancePhase- Rapidexcretion(after3minutes)
AnormalMAG3renogram.Thetracerclearsfromthecollectingsystemwithoutneedfordiuretic.
Case2b:PartiallyObstructedLeftKidney
ThepatientfromCase2a,wentontohaveanopenleftpyeloplasty.ArepeatMAG3renogram demonstratesretainedactivity intheleftkidney.However,itnowrespondstoIVfurosemidewhichindicatesapartiallyobstructedsystem.
References1. Mandell,J.(2018). Coreradiology.Cambridge:CambridgeUnversity Press,p.582.2. Eskild-JensenA,GordonI,Piepsz A,Frøkiaer J.Interpretationoftherenogram:problemsandpitfallsinhydronephrosis inchildren.BJUInt.2004Oct;94(6):887-92.
Case1:BilateralRenalOutflowObstruction
- Thereisasymmetricuptakeinthetwokidneys,R<L.- Causesofasymmetric,decreaseduptakeinonekidney,couldbe
duetorenalarteryorvenousthrombosis,chronicobstructionorinfections.
- Bothkidneysshowreducedupslopeoftheflowphasesuggestiveofreducedrenalperfusion.
- Delayedcorticaluptakeimpliesimpairedrenalfunction- Retentionofactivityinbothkidneysintheclearancephasewith
nosignificantresponsetoIVfrusemidesuggestsbilateraloutflowtractobstruction
- Below,CTofthesamepatientshowsgrossrightPUJdilatationandthereisalsolefthydronephrosis
Case2a:ObstructedLeftKidney
- Theflowphaseandcorticalphasearenormal.- Leftkidneyshowsretentionofactivityintheclearancephase
whichdoesnotrespondtoIVfurosemide- Theleftkidneyisobstructedascanalsobeseeninthedynamic
planarimages.
Case3:DilatedButUnobstructedLeftKidney
- Normalflowandcorticalphasesinbothkidneys- Thereisslowclearance intheleftkidneywhichcontinuespost
furosemideinkeepingwithadilatedbutunobstructedsystem.
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