Pictorial Review of Urinary Tract Obstruction in Tc-99m ... · Pictorial Review of Urinary Tract...

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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Clearance