NIS - Cothron Hartman Daffner McDonald Contrast Media ...
Transcript of NIS - Cothron Hartman Daffner McDonald Contrast Media ...
Non-InterpretiveSkillsContrastMediaUses,Reactions,&Treatments
BeforeYouBeginThismoduleisintendedprimarilyforclinicalmedicalstudentsorinternsintendingtolearnorreviewnon-interpretiveradiologyskills.
Pleasenotethatwhilenotintegral,thismoduleseriesassumessomefamiliaritywithbasicimagingtechniquesandinterpretiveskills.Ifyouwishtolearnorreviewtheseconcepts,pleaseseeour“InterpretiveSkills”moduleseries.
Ifmaterialisrepeatedfromanothermodule,itwillbeoutlinedasthistextissothatyouareaware
Objectives
Bytheendofthismodule,studentswillhaveapracticalknowledgeofradiologiccontrastagentsastheyapplytoindications,contraindicationsandcomplications.Interactivecasesandquestionswillhelpthestudentself-evaluate.
1.ContrastBasics2.OralContrast3.IntravenousContrastforCT4.IntravenouscontrastforMRI5.ConclusionandPearls6.Posttest
OverviewPleaseusehyperlinkstoskiptodesiredsectionsasneeded
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WhatIsContrast?
§ Definition: amaterialusedtoenhanceinternalstructures,ie.outlinewalls,defineanatomy,andhelpdemonstrateanypathologiccondition(s)withinthebodyinmedicalimaging.
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OVERVIEW
HowDoTheyWorkforCTorX-rays?
§ Materialswithahighatomicnumber,suchasGadolinium,Iodineinwater-solublecontrastagents,andBariumwillabsorbx-raysandwillberadiopaqueontheradiograph.
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PhotoandRadiographofContrastMedia
(a) Gadolinium based contrast(b) Water-soluble iodine based oral/IV contrast(c) Barium
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ContrastUsesThroughouttheBody
§ Arthrography:throughthejoints§ Myelography:throughthespine§ Angiography:throughthebloodvessels§ Fluoroscopy:throughtheGItract(ie.enemas,fistulogram,post-operativeleak,etc.)
§ Fluoroscopy:throughtheGUtract(ie.cystogram,urethrogram,hysterosalpingogram)
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WhenWouldContrastNotBeHelpful?
§ KidneyStones§ RetroperitonealBleed§ IntracranialHemorrhage§ OtherContraindicationsDiscussedLater
Teaching Point: There is enough inherent contrast within each of these processes to make the diagnosis without contrast.
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Pre(A),Post(B),andDelayed/Pyelographic(C)CTimagesdemonstratedifferentstagesofcontrastexcretionthroughthekidneys.Notehowtherenalcalculusisbestseenonpre-contrastimages,andbecomesprogressivelyobscuredascontrastaccumulatesinthekidneyandcollectingsystem.
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OralContrast:BariumvsWater-Soluble
§InertSubstance§BetterOpacification/distentionofGItract§BetterMucosalDetail§Resistanttodilution§Cheap
§IVorotherroute§Reabsorbed
§SeveredesmoplasticreactionifoutsideGItract§DelayedtransitmaycauseBariumtoinspissate§Mayobscurepathologyonsubsequentscans
§Irritatingtotracheobronchialtree§Lessdistention/poorercoating§Moreexpensive
Barium
Water Soluble
Pros Cons
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OralContrastExtravasation
WatersolublecontrastwasusedastheinitialcontrastagenttodiagnosethisesophagealruptureinthispatientwhohadBoerhaaveSyndrome.
Teaching Point: Use water-soluble contrast if GI leak is suspected.
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ExampleofUGIusingBarium
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*
§A malignant stricture (arrow) in the mid esophagus is nicely demonstrated in this barium esophogram.
§CT scan demonstrates a malignant mediastinal mass (*) that was causing the esophageal stricture.
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WhenDoYouUseIntravenousContrast?
IV contrast is given to make lesions more conspicuous and to increase vascular & soft tissue detail.
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CTimagesoftheliverpre,immediatepost-contrast,anddelayedphase(A,B,C)showprogressivenodularenhancementofthislesion,whichendedupbeingahemangioma.
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WhatCanGowrong?
§ Extravasation§ Allergy§ ContrastInducedNephropathy§ MetabolicAcidosis
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Extravasation
Contrast extravasating into the subcutaneous tissues.
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• As a clinician you may inherit this patient and will need to know the signs of... • Ulceration and possible necrosis• Compartment Syndrome • Reflex Sympathetic Dystrophy Syndrome:
Chronic pain syndrome due to trauma to nerve complexes/soft tissue
ComplicationsofExtravasation
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ComplicationsofExtravasation
Skin necrosis after large volume extravasation.
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Howdowetreatthis?§ Always assessthepatientfirst!
§ Aradiologistisafirstlineresponderandwillevaluateforvolumeextravasatedandneurovascularcompromise.
§ Reducepain/Decreaseswellingwithcoldorwarmcompressesandelevation.
§ Hyaluronidasecanbeadministered.§ Surgicalconsult:Volumes>100ml,Progressive
swelling/pain,Decreasedtissueperfusion,Changeinsensation,Skinulceration/blistering
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Always document in patient’s chart!
AllergicReactions
§ IVcontrastisadrugandthereforecanhaveadversereactions.
§ Typeofreactions:• Mild:nausea,vomiting,urticaria,pain,sweats,
shaking,chills,pallor,dizziness• Moderate:symptomaticurticaria,vasovagal
reactions,mildbronchospasm,andtachycardia,hypertension
• Severe:laryngeal/pulmonaryedema,severebronchospasm,seizure,diffuseerythema,severehypotension/cardiacarrest
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ACRPre-TreatmentGuidelinesForContrastAllergy
§ ElectivePremedication:§ Prednisone50mgPO@13,7,&1hourprior+Diphenhydramine50mgPO/IM/IV1hourprior,or...
§ Methylprednisolone32mgPO@12&2hours+antihistamine(asabove).
§ EmergencyPremedication:§ Methylprednisolone40mgorHydrocortisone200mgIVq4prior+antihistamine(asabove).
§ Steroidsnoteffectiveifgiven<4-6hoursprior
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TreatmentofReactions
• A:Airway,O2,Assessment,Assistance,Access• B:Breathing(CPR),Bag-valve-mask• C:Circulatoryassistance->IVfluids• D:Drugs
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TreatmentofReactions• Urticaria:
• Diphenhydramine50mgPO/IM/IV
• ifsevere,alphaagonistorEpi0.1-0.3mgSC(ifnocontraindications)
• Facial/LaryngealEdema:
• GiveO2
• Alphaagonist
• Ifhypotensive,Epi0.1-0.3mlSC/IMupto1mg(Alternatively1-3mlIV)
• Bronchospasm:
• GiveO2,monitorEKG,BP,andpulseox
• Betaagonistinhalers2-3puffsPRN
• Ifnoresponse,Epi0.1-0.3mlSC/IMupto1mg(Alternatively1-3mlIV)
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TreatmentofReactions• HypotensionwithTachycardia(Anaphylaxis):
• Trendelenburgposition
• GiveO2,monitorvitals
• RapidIVfluidadministration
• Epi1-3mlIVupto1mg,ifpoorresponsetoabove
• HypotensionwithBradycardia(VasovagalReaction):
• Trendelenburgposition
• Give02,monitorvitals
• RapidIVfluidadministration
• Atropine0.6-1mgIVslowly,ifpoorresponsetoabove(repeatupto2-3mg
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ContrastInducedNephropathy(CIN)
• Contrastisexcretedbyglomerularfiltration.
• Patientswithborderlinerenalfunctionmayexperienceglomerular/tubulardamageresultingintransientimpairmentinrenalfunction/oliguria.
• ThereisnouniversallyaccepteddefinitionforCIN,butanincreaseof0.5mg/dlwithin48hoursofcontrastadministrationiswidelyaccepted.(Solomonetal)
• Serumcreatininehaslimitationsasanaccuratemeasureofrenalfunction.E-GFR(estimatedglomerularfiltrationrate)ismorecommonlyused.
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StagesofChronicKidneyDisease(CKD)
Stage of CKD Description GFR ml/min/1.73 m2
1 Kidney damage with normal GFR
90 or more
2 Mildly decreased GFR 60-89
3 Moderately decreased GFR
30-59
4 Severely decreased GFR 15-29
5 Renal failure-markedly decreased GFR
<15 (or dialysis)
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WhyisCKDImportant?§ ContrastadministrationhasariskofconvertingCKDintoESRDandtherebynecessitatingdialysis.
§ Avoidance/alternativesarerecommendedforpatientswithStage4-5CKD.
§ AKIisanabsolutecontraindicationtointravenouscontrast.
§ Incaseslikethis,cliniciansneedtocommunicatewiththeradiologistabouttherisks,benefits,andpossibleimagingalternatives,suchasnon-contrastCTorUS.
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CINSpecialConsideration:Metformin
• Metforminisclearedbyrenaltubularsecretion.
• Accumulationinthebloodstreamcanleadtolifethreateninglacticacidosis.
• Metforminshouldbeheldfor24hourspriortocontrast.
• Itmayberesumedupondocumentingreturntonormalrenalfunction
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MRIContrast
§ LikeCT,intravenouscontrasthelpsinthediagnosisofmanyimportantpathologies
§ Gadolinium(64Gd)isaspecialmetalthathasstrongparamagneticproperties,effectingtherelaxationtimeinthescanningsequence.
§ Advantagesaresimilartootherformsofenhancedradiologicstudies,ie.bettervisualizationofanatomyandpathology.
§ ThefreeGdionisinherentlytoxictohumans,andmustbechelatedwithDTPAtobesafelyexcretedbythekidney.
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• MRIImagespre(A)andpost(B)contrastofalesion(blackarrow)intherighthepaticlobe.
• Notethelesionismuchmoreconspicuousonthepost-contrastimagewherethereisalsocontrastopacificationofthevasculatureincludingtheaorta(whitearrow).
• ThislesionendedupbeinganFNH.
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ContraindicationstoGadolinium
• Gadoliniumisadrugandthereforehaspotentialforadversereactionsjustlikeiodinatedcontrast.
• Pregnancy:Gadoliniumpassesthroughtheplacentaandaccumulatesintheamnioticfluid,thereforeonlygiveninemergencies.
• RenalDiseaseprecludesnormalexcretionandleadstoincreaseddurationofexposure.
• Accumulationinasciticfluidhasthepotentialfordelayedexposure,howevertherearenoreportedcases.
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NephrogenicSystemicFibrosis
§ Definition:Arareandprogressivefibrosingsyndromeinvolvingtheskin,joints,eyes,andinternalorgans.
§ Describedonlyinpatientswithimpairedrenalfunction.§ Incaseslikethis,Gadoliniumisnotgivenwithoutdiscussingtherisks,benefits,andalternativeswiththepatientandreferringphysician.
§ Whennecessary,usethelowestpossibleeffectivedoseandagentswithlessincidenceofNSF.
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ConclusionandPearls• Commonlyusedcontrastagentsmaybecategorizedasparticulate(barium),water-soluble(ionicandnonionic),andparamagnetic.
• Bariumremainsthemainstayforradiographicevaluationofthe(holloworgansofthe)GItract.However,bariumistoxicoutsidethelumenofthebowel.
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ConclusionandPearls• Contrastagentscanresultinlifethreateningreactionswheningestedorinjectedintoapatient
• AvoidusinggadoliniuminpatientswithrenalfailurebecauseoftheriskofNSF
• Theradiologistandorderingphysicianshouldworktogethertodecidetheriskbenefitofadministeringcontrastwithrespecttorenalfunctionandallergy/needforpremedication.
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PostTest
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1.A36yearoldfemale,postRoux-en-YgastricbypasspresentstothedepartmentforamodifiedUGI.Whatcontrastagentdoyoubeginwithtoruleoutleak?
A. BariumB. Watersolublecontrast
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Biscorrect
• Whenrulingoutaleak,startwithwatersolublecontrast.BariumcanresultinaseveredesmoplasticreactionifitextendsoutsideoftheGItract.
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2.Forwhichofthefollowingconditionswouldcontrastbehelpfulinmakingthediagnosis?
A. KidneyStonesB. IntracranialHemorrhageC. HepatocellularCarcinomaD. RetroperitonealBleed
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AnswerCiscorrect• Thereisenoughinherentcontrastwithinkidneystones,retroperitonealbleedandintracranialhemorrhagetomakethediagnosiswithoutcontrast.Infact,thepathologicprocessesintheseinstancesmaybeobscuredbythecontrast.
• Intravenouscontrastwouldbehelpfulforthediagnosisofhepatocellularcarcinoma,ahypervasculartumorwhichenhancestoagreaterdegreethantheliveraftertheadministrationofintravenouscontrast.
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3.A47yearoldmalepresentsforfollowupenhancedCTandreportedhivesafterthelaststudy.Whatshouldyoudo?
A. Prednisone50mgPO@13,7,&1hourprior+Diphenhydramine50mgPO/IM/IV1hourprior
B. Methylprednisolone40mgIV3hourspriortocontrastadministration.
C. Acetylcysteine140mg/kgPO/NGx1D. Donothing.
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AnswerAiscorrect
• Intravenouscontrastcanbethoughtofasamedication.Likeanymedication,patientscandevelopallergies—someofwhichcanbelifethreatening.Specificprotocolshavebeenestablishedtodecreasetheprobabilityofacontrastreactionusingacombinationofsteroidsanddiphenhydramine.
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4.A63yearoldfemalejustreceivedIVcontrastandreportedfeeling“lightheaded.”BP80/45HR150.Whichofthefollowingarenotindicated?
A. SupplementalO2B. Atropine0.6mgIVC. TrendelenburgpositionD. Epinephrine1mlIV
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AnswerBiscorrect• Thisisanexampleofananaphylacticreactionwhichdevelopedaftercontrastadministration.Pleasenotethatthepatientishypotensivewithtachycardia.Rememberthatintravenouscontrastisamedicationandcanresultinlifethreateningallergicreactions.Asalways,assessthepatientsfirstanddecideontheseverityofthesituationbytakingvitalsignsandexaminingthepatient.Establishedprotocolsforthetreatmentofthesereactionsincludeoxygen,ivfluid,TrendelenbergpositionandEpinephrine(IVorIM).
•• Vasovagalreactionsontheotherhandresultinahypotensivepatientwithbradycardia.Atropineisthemedicationofchoicetotreatthesepatients.
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5.A67yearoldfemaleondialysishasasuspectedbraintumor.CananMRIbedoneusingGadolinium?Why?
A. YesB. NoC. Depends
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AnswerCiscorrect• Nephrogenicsystemicfibrosis(NSF)isarareandprogressivefibrosingsyndromeinvolvingtheskin,joints,eyes,andinternalorgans.NSFhasbeendescribedonlyinpatientswithimpairedrenalfunctionandthoseondialysis.Inthesepatients,Gadoliniumisnotgivenwithoutdiscussingtherisks,benefits,andalternatives(contrastenhancedCTorMRIwithoutcontrast)withthepatientandreferringphysician.WhenacontrastenhancedMRIisdeemednecessary,theradiologistwillusethelowestpossibleeffectivedoseandagentswithlessincidenceofNSF.
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References
• ACRManualonContrastMedia,Version8.0.Reston,VA:AmericanCollegeofRadiology,2012.
• ACR-SPRPracticeGuidelinefortheUseofIntravascularContrastMedia.Reston,VA:AmericanCollegeofRadiology,2012rev.
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