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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