More Related Content Similar to CONTRAST MEDIA.pptx (20) More from Josephmwanika (12) CONTRAST MEDIA.pptx8. •RADIOGRAPHIC CONTRAST MEDIA ARE DIVIDED INTO POSITIVE AND NEGATIVE
CONTRAST AGENTS.
Thepositivecontrastmedia
attenuate X-raysmorethando
thebodysofttissuesandcanbe
dividedintowatersolubleiodine
agentsandnonwatersoluble
bariumagents. Negativecontrastmedia
attenuate X-rayslessthando
thebodysofttissues.Nonegative
contrastmediaarecommercially
available.(airandgas)
9. IODINATEDCONTRASTMEDIA
Iodinatedcontrastmediaarecontrastagentsthatcontainiodineatomsused
forx-ray-basedimagingmodalitiessuchascomputedtomography(CT).
Theycanalsobeusedinfluoroscopy,angiographyandvenography,andeven
occasionally,plainradiography.
Althoughtheintravenousrouteof administrationismostcommon,theyare
alsoadministeredbymanyotherroutes,includinggastrointestinal(oral,
rectal),cystourethral,vaginal,intraosseous,etc.
10. Physics
The ability todistinguishbetweentissuesof different x-ray attenuation(image contrast)
dependsupon twotypesof interactions betweenphotons and matter:Compton scatteringand
photoelectric absorption.
Boththeseinteractions dependuponphysical density,butthelatteralsodependsuponatomic
numberof thematter.
Asiodine hasa highatomic number, 53,comparedtomosttissuesinthebody,the
administration ofiodinated material producesimagecontrast duetodifferential photoelectric
absorption.
Iodine hasaparticular advantageasacontrastagentbecausethek-shellbinding energy (k-
edge)is 33.2keV,similar to theaverageenergyof x-raysusedindiagnosticradiography .When
theincidentx-ray energyiscloser tothek-edgeof theatomit encounters,photoelectric
absorption ismore likely tooccur.
Differences inphotoelectric absorption acrossdifferent x-ray energiesisharnessedindual-
energyCT, inwhichpatientsarescannedwithtwodifferent x-ray spectra.
Materialdecomposition techniquesallows thecreationof virtual imagesinwhichiodine is
preferentially increasedinintensity(iodine map)orremoved altogether (virtual non-contrast),
whichcanhold additional diagnostic value.
13. Highosmolalitycontrastmedia
High osmolality contrast media(HOCM) are approximately five toeighttimes
theosmolality of serum.
Ingeneral, HOCM are ionic compounds thatinclude abenzenering withthree
iodine atomsandasidechaincontaining acarboxylicacid (-COOH) group.
Asthefirst generation of iodinated contrastagents,HOCM wereassociated
withhighratesof adverseeventsandfell out offavor inthe1990sfor
intravascular andintrathecal purposes.
HOCM remainusedfor gastrointestinal andcystourethral
administration, including thefollowing agents:
Diatrizoate sodium/meglumine(Gastrografin, MD-Gastroview, Cystografin)
Iothalamate sodium/meglumine (Conray, Cysto-Conray)
14. Lowosmolalitycontrastmedia
Lowosmolalitycontrastmedia(LOCM)arelessthanthreetimestheosmolalityofhumanserumand
preferred forintravascularandintrathecaladministration.
ModernLOCMaregenerally,butnotalways,nonionicmonomerscomposedof tri-iodinatedbenzene
ringswithvarioussidechainsthatcontainpolaralcohol(-OH)groupsthatmakethemwater-soluble
LOCMincurrentuseincludethefollowing:
1. iopamidol(Isovue)
2. iohexol (Omnipaque)
3. iopromide(Ultravist)
4. ioversol (Optiray)
5. ioxilan(Oxilan)
TheLOCMcategoryalsoincludesiso-osmolalcontrastmedia(IOCM),whichareapproximatelythesame
osmolalityasserum.
TheonlyIOCMincurrentuseisanon-ionicdimer,whichiscomposedoftwocovalentlyboundtri-
iodinatedbenzenerings:
iodixanol(Visipaque)
Thedimerstructureof iodixanolfits ahigherconcentrationofiodine atomsperosmole,permitting
diagnosticlevelsofcontrastopacificationatlesstoxicosmolality.
Non-ionicLOCMareavailableinvaryingconcentrationsrangingfrom240to400mgiodine/mL.
Higherconcentrationformulationsproduceagreaterpeakofenhancement(measuredinHounsfield
units)butarealsomoreviscous.
16. Administration
Intravenous
Contrast injectedintravenously isoften mechanicalviaacomputerizedpressureinjector.
The AmericanCollege of Radiology recommendsacannula of20-gauge orlarger for the
mechanicalinjection of intravenous contrastfor anyinjections thatrequire aflow rate higher
than3mL/s.
The prewarming of contrastagents,particular onesof higherconcentration (370 mg/mL)will
lower thechancesof contrastextravasation.
Intraosseous
Inthecontext ofthecritically ill patientwhere intravenous accessis notpossible, iodinated
contrastcanbeadministeredvia anintraosseous injection.
Pressureratesmustbehighduetothe intramedullary pressurewithinthebone.
According totheACR Committee onDrugsandContrast Media, therearenoreported
complications of intraosseous injections at5 mL/s.
The humerusisthemostcommonly acceptedsiteof injection .
17. BARIUM SULFATE (BASO4
Bariumsulfate(BaSO4),often just called bariuminradiology parlance, is anionic salt
of barium(Ba) ametallic chemicalelementwith atomicnumber56.
Bariumsulfate forms thebasisfor arangeof contrastmediausedinfluoroscopic
examinations ofthegastrointestinal tract.
Unlike barium and manyof itsother salts,bariumsulfate isinsoluble inwaterand
therefore verylittle of thetoxicbariummetal isabsorbedinto thebody.
Indications
Itisthepreferential contrastagentfor gastrointestinal (GI) fluoroscopic
examinations dueto:
1. highattenuationofx-rays
2. lackof absorption from thegutintothebody
3. lackof toxicity (in thegut)
4. Itcanalso befound insomeoral contrastpreparations usedfor CT.
18. Bariumcanbemixedintohigh-density orlow-density suspensions.
Bothsuspensionstypically attenuatex-rays morethanwater-soluble
contrast.
High-density bariumis preferred over water-soluble contrast for fine-detail
evaluation ofthegastrointestinal system(e.g.evaluation for early changes
from Crohn disease).
Suspensionscreatedfor CT useare verylow density.
Dueto itsinsolubility inwater,bariumsulfate contrastmediaaresupplied as
fine particles of thebariumsulfate suspendedinwater.
Often artificial flavourings areaddedtomakethemixturemore palatable.
Itsallergy profile is favourable withveryfew reported reactions.
Historically, allergy wasmore commonwhenexcipients,suchaschocolate,
wereused.
19. Contraindications
Known orstronglysuspectedgastrointestinalperforation
maybeused inevaluationfor possible esophageal perforations.
largevolumeaspirationrisk
priorallergicreaction(rare)
left-sidedcolonicobstruction(relativecontraindication)
ifthebariumcannotexitthecolon, ithas thepotentialtobecome
inspissated andveryhard, leading toaquiteproblematic constipation
21. MRContrastMedia
Magneticresonance(MR) imagingcontrastagentscontain
paramagneticorsuperparamagneticmetalionswhichaffecttheMR
signalpropertiesofthesurroundingtissues.
Theyareusedtoenhancecontrast,tocharacterizelesionsandto
evaluateperfusionandflow-relatedabnormalities.
Theycanalsoprovidefunctionalandmorphologicalinformation.
22. PARAMAGNETIC CONTRAST AGENTS
ParamagneticcontrastagentsaremainlypositiveenhancerswhichreducetheT1andT2
relaxationtimesandincreasetissuesignal
Themostwidelyusedparamagneticcontrastagentsarenon-specificextracellular
gadoliniumchelates.
Theiractiveconstituentisgadolinium,aparamagneticmetalinthelanthanideseries,
whichischaracterizedbyahighmagneticmomentandarelativelyslowelectronic
relaxationtime.
Non-specificextracellulargadoliniumchelatescanbeclassifiedbytheirchemical
structure,macrocyclicorlinear,andbywhethertheyareionicornonionic.
Theyareexcretedviathekidneys.
Paramagneticcontrastagentsalsoincludeliverspecificgadoliniumbasedagents
(gadobenatedimeglumine,Gd-BOPTAandgadoxetate,Gd-EOBDTPA)andmanganese-
basedpreparations[manganesechelate(mangafodipirtrisodium)andfreemanganese
combinedwithvitaminsandaminoacids(topromotetheuptake)fororalintake].
Thesehepatobiliarycontrastagentsaretakenupbyhepatocytesandthenthereis
variablebiliaryexcretion.
Thegadoliniumbasedliverspecificcontrastmediaarealsoexcretedbythekidney
intensityon T1-weightedMRimages.
23. SUPERPARAMAGNETIC CONTRAST AGENTS
Superparamagneticcontrastagentsincludesuperparamagneticiron
oxides(SPIOs) andultrasmallsuperparamagneticironoxides(USPIOs).
TwopreparationsofSPIOsareavailable:ferumoxidesandferucarbotran.
Theseparticulateagentsarecomposedofanironoxidecore,3–5mmin
diameter,coveredbylowmolecularweightdextranforferumoxidesand
bycarbodextranforferucarbotran.
SPIOsareapprovedforliverimagingandUSPIOs areunderconsideration
forMR lymphography.
Afterinjection,SPIOandUSPIOparticlesaremetabolisedintoasoluble,
nonsuperparamagneticformofiron.
Ironisincorporatedintothebodypoolofiron(e.g.ferritin,hemosiderin
andhemoglobin)withinafewdays
24. ULTRASOUND CONTRAST MEDIA
Ultrasoundcontrastagentsproducetheireffect byincreasedback-scatteringof
soundcomparedtothatfromblood,otherfluidsandmosttissues.
Ongreyscaleimagesmicrobubblecontrastagentschangegreyanddarkareastoa
brightertone,whenthecontrastenters influidorblood.
ThespectralDopplerintensityisalsoincreased,withabrighterspectralwaveform
displayedandastrongersoundheard.
UsingcolorDopplertechnique,ultrasoundcontrastagentsenhancethefrequencyor
thepowerintensitygivingrisetostrongercolorencoding.
ThelevelofenhancementoftheDopplersignalsmaybeintheorderofupto30dB.
UltrasoundcontrastagentscanbeusedtoenhanceDopplersignalsfrommostmain
arteries andveins.
Theymaybeusefulfor imagingsolidorgans,e.g.liver,kidney,breast,prostateand
uterus.
Theycanalsobeusedtoenhancecavitiese.g.bladder,ureters, Fallopiantubes,
abscesses.
26. Ultrasound contrast agents(USCA) canalso beclassified basedon their
pharmacokinetic properties andefficacy:
Non-transpulmonary USCAs whichdo notpassthecapillary bedof thelungs
following aperipheralintravenous injection, showonB-mode only inthe
rightventricle, andhaveashort duration effect,
transpulmonaryblood pool USCAs withashort half-life (<5 minafter an
intravenous bolus injection), whichproduce low signalsusing harmonic
imaging atlow acousticpower,
transpulmonaryblood pool USCAs withalonger half-life (>5 minafter an
intravenous bolus injection), whichproduce high signalsusingharmonic
imaging atlow acousticpower,
transpulmonary USCAs withaspecificliver andspleenphasewhichcanbe
shortor long-lived. Theylodge inthesmallvesselsof theliverorspleen, or
aretakenupbyeither thereticuloendothelial systemor bythehepatocytes.
29. SEVERITY(THE AMERICAN COLLEGE OF RADIOLOGY HAS DIVIDED ADVERSE REACTIONS TO
CONTRAST AGENTS INTO THE FOLLOWING CATEGORIES)
Mild
Signs andsymptomsappearself-limitedwithoutevidenceof
progression
Nausea,vomiting Alteredtaste SweatsCough
Itching Rash,hivesWarmth(heat) Pallor
Nasalstuffiness
Headache Flushing Swelling:eyes,faceDizziness
Chills AnxietyShaking
Treatment:Observationandreassurance.Usuallynointerventionor
medicationisrequired;however,thesereactionsmayprogressintoa
moreseverecategory
33. DELAYED CONTRAST REACTIONS
Delayedcontrastreactionscanoccuranywherefrom3hoursto7days
followingtheadministrationofcontrast.
Itisstillimportantforanyoneadministeringintravenouscontrastmediatobe
awareofdelayedreactions.
Withtheexceptionofcontrast-inducednephropathy,themorecommon
reactionsincludea
cutaneousxanthem, pruritiswithouturticaria, nausea,vomiting,
drowsiness,andheadache.
Whilecardiopulmonaryarresthasbeenreported,itisprobablynotrelatedto
newercontrastagents.
Cutaneousreactionsarethemostfrequentformofdelayedcontrastreaction
withareportedincidenceof0.5-9%.
34. Cutaneous reactions varyinsizeand presentationbutare usually pruritic.
For themostpart,thesereactionsare self-limited and symptomscanbe
treatedwithcorticosteroid creams.
Rarecasesmayprogresstobecomesevere,someresemblingStevens-
Johnsonsyndromeora cutaneousvasculitis.
Consultation withadermatologist isappropriate for delayedcutaneous
reactions.
Delayedcutaneous reactionsare morecommon inpatientswhohavehada
previous contrastreaction andinthose whohavebeentreatedwithinthe
past2years,or arecurrently beingtreated withinterleukin-2 (IL-2).
While theexactmechanismof thedelayedreactionisunknown,theycan
recurif thesamecontrastmediumisadministeredagain.Therefore, itis
possible thatthesedelayed reactions areT-cell mediated.Assuch,
prophylaxis withoral corticosteroids maynot beuseful
36. ANAPHYLACTOIDREACTIONSPathophysiology
Anaphylactic reactions areeventsinitiated whenan allergen and IgE combine
toinducemastcells toreleasechemicalmediators.
Mastcellsoriginate from bone marrow precursors anddevelop intheorgans in
whichtheycometoreside.
Principal locations aretheskin, respiratory tract,GI tract,andblood vessels.
Allergen-specific IgE is boundon thesurface ofmastcells.
The allergen-IgE complexactivatesthemastcellandinducesit torelease
histamineaswell asother mediators.
Histaminebindsto specificreceptorsites.H1receptorsarefound inendothelial
andsmoothmusclecellsandinthecentral nervoussystem.
H2receptors areingastric parietal cells andininflammatory cells.
The natureof ananaphylacticreaction dependsupon thelocation whereit
occurs.
Intheskin, vasodilatation producesurticaria anderythema.
Inmucosa,vasodilatation produces nasalcongestion and laryngeal edema.
Intherespiratory tract,smooth musclecontraction produces bronchospasm.In
peripheral vessels,vasodilatation produceshypotensionandshock.
Gastrointestinal reactions include nausea,vomiting, diarrhea, andcramps.
37. Anaphylactoid reactions areidentical toanaphylacticreactions intheir
manifestations,buttheyarenot initiated byanallergen-IgE complex.
Acutecontrastreactions areincluded inthisgroup.
The distinctionbetweenanaphylacticandanaphylactoid reactions issubtle,butit
hascertainimportant implications for theuseofiodinated contrast:
1) Areaction canoccur eventhefirst timecontrastisadministered.
2) The severityof areactionisnotdose-related; therefore atestdose isof novalue.
3) The occurrenceof acontrastreaction doesnot necessarilymeanthatitwill
occur again(although therisk isgreaterthatitmay).
4) Even thoughthecirculating contrastissystemic,thenatureof theresponseis
variable.
5) More thanone typeof reaction mayoccur simultaneously.
Aswithanaphylacticreactions, certain riskfactors makepatientsmore
susceptibleto iodinated contrast(anaphylactoid) reactions
: Allergic asthma Drugallergies Food allergies Prior reactions tocontrast
39. AN EMERGENCY BOX OR CART
shouldbeintheimmediatevicinity.
itshouldbesealed(notlocked)sothatitwillbeintactwhenneeded.
Itmustbeperiodicallyinspected(andrecordedandsignedonacheck-offlog)to
insurethatitisfullystockedandthatnoneofitscontentshaveexpired
Alistofmedications,indications,anddirectionsfortheiruseandalistof
emergencyphonenumbersshouldbeprominentlydisplayed.
Astethoscopeandbloodpressurecuffofsufficientqualityforreliableclinical
useshouldbeincluded.
ThereshouldbeabagofisotonicIVsolution(normalsalineorRinger’ssolution)
withIVtubing.
Anappropriateselectionofneedlesandsyringesandeverythingelseneededto
drawupmedicationsorstartadditionalIVsshouldbeavailable.
AnAmbubag™withaproperassortmentofmasks,laryngoscopeswith
endotrachealtubes,andairwaysshouldbeincluded.
Thereshouldbeaflashlightandtonguedepressors
Anoxygentankandtubingshouldbecloseathand
Aclipboardwithpaperforflowsheetsisveryhelpful.
Allpoliciesandproceduresshouldbedatedandperiodicallyreviewed
40. Whensummonedtoassessapatientwhomaybehavinganadversereaction, you
mustbeable toactquickly, purposefully, andeffectively.
1. Ascertainfrom thetechnologist ornursewhattheproblem is. Speaktothe
patienttoobtain additional information anddeterminehow he/sheresponds.
2. Consult information onpertinentmedicalhistory (this should beobtained before
thecontrastinfusion isstarted).
3. Immediatelystop thecontrast infusion, hook up isotonic IVfluids, andopen theIV
wide.
4. Obtain vitalsigns.
5. Check theairwayand breathing.
6. Check skincolor, temperature,and dryness.
7. Donot hesitatetoadminister oxygenbymask(6–10 liters/min)
8. elevatethepatient’slegsfor hypotension, orstartadditional Ivsor other drugs
asappropriate.
9. Reassessthepatient,andmakeeffective decisions ascircumstanceschange.
10. Those assistingshould executetheirdutiesquietly, minimizinganxiety-
provoking conversation.
43. :Diphenhydramine
Anantihistamine whichis anH-1
receptorsiteblocker.
Itshould beusedonly totreatmild
urticaria, whichislikely toresolve on
itsown,andwhere itisdeemed
desirable toprovide symptomatic
relief bypreventingfurther reactions.
Should not beusedfor severe
urticaria orother more significant
reactions
ADULT DOSE: 25–50 mgIV orIM
Caution: Causesdrowsiness. Patient
should not drive oroperate
machineryfor 4-6 hours.
PEDIATRIC DOSE :1mg/kg
45. Epinephrine:
Adrug whichisabasicsympathetic
agonist
Asanalpha agonist,epinephrine is
usedtotreatsevereurticaria, facial
edema,andlaryngeal edema.
Asabeta-2agonist,itmaybeneeded
totreatbronchospasm. Itmustbe
usedwithcautioninpatientswith
cardiacdiseaseandhypertension
DOSE: Subcutaneous:1:1,000(1
mg/mL)0.1–0.3mL(0.1 –0.3 mg)
DOSE: Intravenous: 1:10,000(0.1
mg/mL)1mLIVslowly every3–5
minutesMayrepeat upto1mg
maximum
51. Riskfactorsinclude:
Age>65years
Diabetestreatedwithinsulinorotherprescribedmedication
Receivingchemotherapyor aminoglycosidewithinthepast1month
Diagnosisof acollagenvasculardisease
Diagnosisof aparaproteinemiasyndrome/disease(e.g. multiple
myeloma)
Historyofakidneytransplant,renaltumor,renalsurgery,orsingle
kidney
Historyofendstageliverdisease
Historyofseverecongestiveheartfailure
Nephrotoxicityprevention:
Detailedpatienthistorybeforeprocedure
Screeningforrenaldisease(serum creatinine)escptheoneswiththe
aboveriskfactors.
54. VASOVAGALREACTIONS
Vasovagalreactionsarecharacterizedbybradycardiaand
hypotension.
Initialresuscitationshouldincludeelevatingthelegsand/orplacing
thepatientinaTrendelenburgpositionandadministeringoxygenat
therateof6–10liters/minute.
Atropinemaybeusedintheinitialtreatmentof bradycardia.
Epinephrinemaybenecessary.
IVfluidsareusedtotreathypotensionandshouldbeadministered
rapidly.
Itisimportanttomonitorvitalsignsfrequentlytotitratetheamountof
medicationsandfluidsthatareused.
57. EMERGENCYRESPONSE
Immediatecessation of injectionwhenaproblemisdetected.
Notificationofresponsible physicians.
Initialtreatment:
a.Elevatetheaffectedextremityabovetheleveloftheheart
b.Intermittent,brief compression tomilkthe extravasatecentrally,canbeapplied
withanacewrap.(DONOTleavethewraponfor morethan1minutetoavoid
compartmentsyndrome.)
cObservation
d.Notificationofthereferring physicianifthepatientbecomessymptomatic.
Indicationsforplasticsurgeryconsultation(anyoneofthefollowing):
a.Progressive swellingorpain
b.Decreasedcapillaryrefill
c.Alteredsensation
d.Skinulcerationorblistering.
Instructionsaregiventothepatient.
ollow-upcalls.
Documentation.
58. CONCLUSIONS
Although contrastagentsarewidely usedwithsafe outcomesandlittle orno
sideeffects, adversereactionsnonetheless mayoccur. Theymaybesevere,
andtheymayprogress rapidly. Successful patientmanagementduring
contrastenhanced examinations requiresall ofthefollowing:
1. Knowledge ofthepatient’smedical history.
2. Patientpreparation, including premedication, ifnecessary.
3. Proper selection oftheagenttobeused.
4. Knowledge ofthepathophysiology of contrastreactions.
5. Prompt recognition andaccurateassessmentof reactions.
6. Immediateavailability of necessaryequipmentand drugs.
7. Adequateprior planning andtraining.
8. Current knowledge of medicationsandothertreatmentoptions.
Insummary,vigilance andattention todetail arekey.Expecttheunexpected
andbeprepared.
Editor's Notes Rarely observed by radiologist
Not brought to the radiologist attention later