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Managing Incidental Findings on Abdominal CT White Paper of the ACR Incidental Findings Managing Incidental Findings on Abdominal CT White Paper of the ACR Incidental Findings

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Managing Incidental Findings on Abdominal CT White Paper of the ACR Incidental Findings - PPT Presentation

Berland MD Stuart G Silverman MD Richard M Gore MD William W MayoSmith MD Alec J Megibow MD MPH Judy Yee MD James A Brink MD Mark E Baker MD Michael P Federle MD W Dennis Foley MD Isaac R Francis MD Brian R Herts MD Gary M Israel MD Glenn K ID: 34073

Berland Stuart

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ManagingIncidentalFindingsonAbdominalCT:WhitePaperoftheACRIncidentalFindingsCommitteeLincolnL.Berland,MD,StuartG.Silverman,MD,RichardM.Gore,MDWilliamW.Mayo-Smith,MD,AlecJ.Megibow,MD,MPH,JudyYee,MDJamesA.Brink,MD,MarkE.Baker,MD,MichaelP.Federle,MDW.DennisFoley,MD,IsaacR.Francis,MD,BrianR.Herts,MDGaryM.Israel,MD,GlennKrinsky,MD,JoelF.Platt,MDWilliamP.Shuman,MD,AndrewJ.Taylor,MDAsmultidetectorCThascometoplayamorecentralroleinmedicalcareandasCTimagequalityhasimproved,therehasbeenanincreaseinthefrequencyofdetecting“incidentalndings,”denedasndingsthatareunrelatedtotheclinicalindicationfortheimagingexaminationperformed.These“incidentalomas,”astheyarealsocalled,oftenconfoundphysiciansandpatientswithhowtomanagethem.Althoughitisknownthatmostincidentalndingsarelikelybenignandoftenhavelittleornoclinicalsignicance,theinclinationtoevaluatethemisoftendrivenbyphysicianandpatientunwillingnesstoacceptuncertainty,evengiventherarepossibilityofanimportantdiagnosis.Theevaluationandsurveil-lanceofincidentalndingshavealsobeencitedasamongthecausesfortheincreasedutilizationofcross-sectionalimaging.Indeed,incidentalndingsmaybeserious,andhence,whenandhowtoevaluatethemareunclear.Theworkupofincidentalomashasvariedwidelybyphysicianandregion,andsomestandardizationisdesirableinlightofthecurrentneedtolimitcostsandreducerisktopatients.Subjectingapatientwithanincidentalomatounnecessarytestingandtreatmentcanresultinapotentiallyinjuriousandexpensivecascadeoftestsandprocedures.Withtheparticipationofotherradiologicorganizationslistedherein,theACRformedtheIncidentalFindingsCommitteetoderiveapracticalandmedicallyappropriateapproachtomanagingincidentalndingsonCTscansoftheabdomenandpelvis.Thecommitteehasusedaconsensusmethodbasedonrepeatedreviewsandrevisionsofthisdocumentandacollectivereviewandinterpretationofrelevantliterature.Thiswhitepaperprovidesguidancedevelopedbythiscommitteeforaddressingincidentalndingsinthekidneys,liver,adrenalglands,andpancreas.KeyWords:Incidentalndings,incidentaloma,pancreaticcyst,renalcyst,liverlesion,adrenalnoduleJAmCollRadiol2010;7:754-773.Copyright꤀2010AmericanCollegeofRadiologyThiswhitepaperismeantnottocomprehensivelyreviewtheinterpretationandmanagementofsolidmassesineachorgansystembuttoprovidegeneralguidanceformanagingincidentallydiscoveredmasses,appreciatingthatindividualwillvarydependingoneachpatient’sspeciccircum-stances;theclinicalenvironment,availableresources;andthejudgmentofthepractitioner.Also,thetermhasnot DepartmentofRadiology,UniversityofAlabamaatBirmingham,Birming-ham,Alabama.DepartmentofRadiology,BrighamandWomen’sHospital,Boston,Massa-DepartmentofRadiology,EvanstonHospital,Evanston,Illinois.DepartmentofRadiology,BrownUniversitySchoolofMedicine,Provi-dence,RhodeIsland.DepartmentofRadiology,NYU-LangoneMedicalCenter,NewYork,NewYork.DepartmentofRadiology,UniversityofCalifornia,SanFrancisco,SanFran-cisco,California.DepartmentofDiagnosticRadiology,YaleUniversitySchoolofMedicine,NewHaven,Connecticut.DepartmentofRadiology,ClevelandClinic,Cleveland,Ohio. DepartmentofRadiology,StanfordUniversityMedicalCenter,Stanford,DepartmentofRadiology,MedicalCollegeofWisconsin,Milwaukee,Wisconsin.DepartmentofRadiology,UniversityofMichigan,AnnArbor,Michigan.RadiologyAssociatesofRidgewood,PA,Waldwick,NewJersey.DepartmentofRadiology,UniversityofWashingtonSchoolofMedicine,Seattle,Washington.DepartmentofRadiology,VirginiaCommonwealthUniversityMedicalCenter,Richmond,Virginia.Correspondingauthorandreprints:LincolnL.Berland,MD,UniversityofAlabamaatBirmingham,DepartmentofRadiology,619S19thStreet,N348,Birmingham,AL35249-1900;e-mail: ꤀2010AmericanCollegeofRadiologyDOI10.1016/j.jacr.2010.06.013 beenusedinthiswhitepapertoavoidtheimplicationthatthisrepresentsacomponentoftheACRPracticeGuidelinesandTechnicalStandards(whichrepresentofcialACRpolicy,hav-ingundergonearigorousdraftingandreviewprocessculminat-inginapprovalbytheACRCouncil),ortheACRAppropri-atenessCriteria(whichuseaformalconsensus-buildingapproachusingamodiedDelphitechnique).Thiswhitepa-per,whichrepresentsthecollectiveexperienceoftheIncidentalFindingsCommittee,usingalessformalprocessofrepeatedreviewsandrevisionsofthedraftdocument,doesnotrepresentofcialACRpolicy.Forthesereasons,thiswhitepapershouldnotbeusedtoestablishthelegalstandardofcareinanypartic-ularsituation.Therapidincreaseintheutilizationofcross-sectionalimagingexaminationsoverthepasttwodecades,com-binedwiththeongoingimprovementinthespatialandcontrastresolutionofthesestudies,hasledtoamarkedincreaseinthenumberofndingsdetectedthatareun-relatedtotheprimaryobjectivesoftheexaminationsexaminations.Anincidentalnding,alsoknownasaninciden-taloma,maybedenedas鍡渀incidentallydiscoveredmassorlesion,detectedbyCT,MRI,orotherimagingmodalityperformedforanunrelatedreason”reason”.Al-thoughsuchndingsareincidentaltotheprimarypur-poseofthestudy,oneanalysissuggested,“Someresearchandclinicalactivitiesaresopronetogeneratingndingsnotintentionallysoughtthatitisdisingenuoustotermthem‘unanticipated’eveniftheirprecisenaturecannotbeanticipatedinadvance”advance”.Moreimportantthanthedenitionistheactionthateachsuchndinginvokes.So,weareaskedtoconsider,“Whatistheresponsibleuseofinformationthatnobodyaskedfor?”for?”.Theburdenofextracostswithincidentalndingsoncross-sectionalimaginghasalsoraisedconcernswithinthegovernmentandthird-partypayersasmedicalimag-ingutilizationandexpenditureshaverisen.Arecentex-ampleofthiswasseenintheMay2009CMSnoncover-agedecisionregardingscreeningCTcolonographycolonography.AlthoughCTcolonographyfocusesondetectingcolo-rectalpolypstopreventcolorectalcarcinoma,anunen-hanced,low–radiationdoseCTscanofthelowerchest,entireabdomen,andpelviscontainsclinicallysignicantincidentalndingsin5%to16%ofasymptomaticpa-pa-,withahigherfrequencyinsymptom-aticpatientspatients.ThenoncoveragedecisionbyCMScitedconcernforthecostsofevaluatingextraco-lonicndingsthatarediagnosticallyindeterminate.OtherexistingordevelopingtechnologiesmayfacethistypeofeconomicscrutinyasCMSandotherthird-partypayersbecomemorefocusedoncostcontainment.Althoughcountlessstudieshavebeendevotedtode-scribingndingsrelatedtospecicmedicalconditions,relativelylittleresearchhasbeendevotedtounderstand-ingincidentalndings.Themostcommonreasontopursueincidentalndingsistodifferentiatebenignfrompotentiallyserious(includingmalignant)lesions.Al-thoughmostincidentalndingsprovetobebenign,theirdiscoveryoftenleadstoacascadeoftestingthatiscostly,provokesanxiety,exposespatientstoradiationunneces-sarily,andmayevencausemorbiditymorbidity.Articlesde-scribingcriteriafordetecting,categorizing,reporting,andmanagingsuchndingshavebeeninconsistentatbestandleavemanyunansweredquestionsquestions.PROJECTOBJECTIVESTheobjectivesofthisprojectwere:todevelopaconsensusonsetsoforgan-specicimagingfeaturesforsomecommonlyaffectedorgansystemswithintheabdomen,whichwillleadtoconsistentdeni-tionsfor,andidenticationof,incidentalndings;todevelopmedicallyappropriateapproachestomanagingincidentalndingsthatarediagnosticallyindeterminate;andtoaddressthedifferencesbetweenunenhanced,low–radiationdoseCTexaminationsandcontrast-en-hancedCTexaminationsusingstandardradiationdosesfordetectingandmanagingincidentalndings.POTENTIALBENEFICIALOUTCOMESOFTHEPROJECTBenetsanticipatedfromthiseffortincluded:reducingriskstopatientsfromadditionalunnecessaryexaminations,includingtherisksofradiationandrisksassociatedwithinterventionalprocedures;limitingthecostsofmanagingincidentalndingstopatientsandthehealthcaresystem;achievinggreaterconsistencyinrecognizing,report-ing,andmanagingincidentalndings,asacomponentofformalqualityimprovementefforts;providingguidancetoradiologistswhoareconcernedabouttheriskforlitigationformissingincidentalnd-ingsthatlaterprovetobeclinicallyimportant;andhelpingfocusresearcheffortstoleadtoanevidence-basedapproachtoincidentalndings.HISTORYOFTHEPROJECTBecauseoftheincreasingrecognitionoftheproblemsandopportunitiesofincidentalndings,considerationofaformalapproachtotheseissuesbeganwithintheACRin2006.TheIncidentalFindingsCommitteewasformedundertheauspicesoftheBodyImagingCom-missionoftheACR.Afterseveralmeetingsandconfer-encecalls,theconceptsandobjectivesdescribedaboveBerlandetal/ManagingIncidentalomasonAbdominalCT wereformulated.Theinitialintentwastodevelopguide-linesanalogoustothoseproducedbytheFleischnerSo-cietyonpulmonarynodulesnodulesandtheconsensuscon-ferencesoftheSocietyofRadiologistsinUltrasoundonthyroidnodulesnodulesandcarotidimagingimaging.BecauseofthekeeninterestamonggroupsbothwithinandoutsidetheACR,thecommittee’sparticipantswererecruitedfrommembersoftheACR,allofwhowerealsofellowsormembersoftheSocietyofComputedBodyTo-mographyandMagneticResonance,theSocietyofGastro-intestinalRadiologists,andtheSocietyofUroradiology.ContactsfromothergroupswithintheACR,includingtheColonCancerCommittee,theAppropriatenessCriteria–AdrenalPanelandtheAppropriatenessCriteria–GIPanel(LiverLesionTopic)alsohelpedensuretheconsistencyoftheguidanceproducedamongthesegroups.CONSENSUSPROCESSExpertradiologistsinrelevantorgansystemswerere-cruitedtoparticipateintheIncidentalFindingsCom-mitteeanditssubcommittees.Weplantofurtherreviewandrevisetheserecommendationsperiodically,onthebasisofcommentsandnewresearch.AlthoughthescopeofaprojecttoaddressincidentalndingsonCTislarge,thecommitteedecidedtodevelopguidanceforalimitednumberoforgansystems.Foursubcommitteeswerees-tablishedtoaddressthelargestnumberofincidentalndingswithintheabdomen,inthekidneys,liver,adre-nalglands,andpancreas.Afthsubcommitteewaschargedwithattemptingtoensuretheuseofcommonterminologyandacommonformat.Thecommitteeelectedtodeferconsideringotherincidentalndingsarisingintheabdomenandpelvis,suchasovarianmasses,spleniclesions,lymphadenopathy,andvascularabnormalities,includingarterialstenoses,abdominalaorticaneurysms,andrenalarteryaneurysms.Themem-bershipofeachsubcommitteeislistedintheAppendix.Eachsubcommitteewastaskedtodeveloporgan-specicguidance,whichwasinitiallyformulatedprimarilybythesubcommitteechairs.Whenthiswascomplete,thesesub-sectionsweredistributedtothesubcommitteemembersforfurthercommentsanddiscussion.Revisionsoftheentiredocumentwerethendistributedtothesubcommitteechairs,andmultiplerevisionsensued.Finally,thedraftwasdistributedtotheentireIncidentalFindingsCommitteeforadditionalreviewtoachieveconsensusandtoarriveatanalmanuscript.ReviewsbyotherACRcommitteeswerealsointegratedintodraftsatappropriatepointsintheprocess.Tofacilitaterapidlyformulatingandclearlycommunicat-ingthisguidance,andtoprovideconvenientgraphicsum-mariesforeasyreference,thecommitteedecidedtoexpressitsrecommendationsinowchartsandtables,buttressedwithexplanatorytext.ELEMENTSOFTHESERECOMMENDATIONSANDFLOWCHARTSCertainsubspecialtieswithinradiologyhaveaddressedin-consistenciesofdocumentationbycreatingstructuredre-porting,suchastheBreastImagingReportingandDataData.Inananalogousway,Zalisetalal,fortheWorkingGrouponVirtualColonoscopy,pro-posed“C-RADS,”whichincludesan鍅鐀classicationsys-temforextracolonicndings.Althoughthislatterclassica-tionsystemhaselementsincommonwiththeserecommendations,itisnotincludedwiththemhere.Intheowchartswithinthiswhitepaper,thealgorithmsuseyellowboxesforstepsthatinvolvedatatoaffectman-agement,suchascategorization,demographics,history,andtheresultsofstudies.Greenboxesrepresentactionsteps,suchasperformingastudy,followingup,orinterveningwithabiopsyorsurgery.Redboxesindicatethattheevalu-ationprocessshouldstop,withnofurtheractionrequired,becausethelesioncanbeconcludedtobebenign.CHALLENGESOFADDRESSINGINCIDENTALFINDINGSOneofthecrucialobstaclestomanagingincidentalnd-ingscost-effectivelyistheunwillingnessofmanyphysi-cianstoacceptuncertaintyevenwhenthechanceofaseriousdiagnosisisextremelyunlikely.Thisunwilling-nessisinpartdrivenbyapaucityofdata,thelackofclear-cutalgorithmswithregardtodiagnosticandtreat-mentstrategies,fearofpotentialmalpracticelitigation,andthedesireofpatientsandtheirfamiliestoadheretotheadage“bettersafethansorry.”Itmaybedifcultforphysiciansorpatientstoappreciateatanintellectualoremotionallevelthatanincidentalndingmightnotneedtoundergofurtherexaminationsorfollow-up.Notonlyarefurthertestslikelytoyieldabenigndiagnosis,butsuchtestingcouldevenleadtomorbiditymorbidity.Ontheotherhand,anincidentalndingcouldrepresentaser-endipitousdiscoveryofaseriousdiagnosis,suchasalargeabdominalaorticaneurysm,andbepotentiallylifesaving;hencetheconundrum.Thediscussionofcostisalsoburdenedwithstrongopinions,withsomebelievingthatcostshouldbenoobstacletoreachingacomfortablelevelofmedicalcertaintyforapositiveornegativediagnosisdiagnosis.Othersmightarguethatmedicalresourcesshouldbebestappliedwheretheyareknowntobemosteffective.However,thereisstrongscienticvalidationforapplyingmedicalstrategiesthatoptimizeresultswhileminimizingcostsandapplying“evidence-based”reason-ingtomedicaldecisionsdecisions.Unfortunately,informationaboutthecost-effective-nessofpursuingincidentalndingsislargelylacking.Therefore,achievingaconsensusofexperts,supportedbyavailableliterature,isareasonableinterimobjectiveJournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 forthisIncidentalFindingsCommittee.However,thereareseveralreasonstohypothesizethatagroupofspecialtyradiologistsfromacademicinstitutionsmightbebiasedtowardtheoveruseofimagingstudies.Forexample,thecultureofattemptingtoachievediagnosticcertaintynotedabovemaybemoreintenseinanacademicenvi-ronment,partlybecauseofthehigherintensityofillnessseenthere.Lessexperiencedphysiciansinresidencyandfellowshipmaybemoreinclinedtodependonimagingstudies,withthisinclinationsupportedbyattendingphysicianswantingtoenhancetheteachingexperience.Also,academicinstitutionsaremorelikelytohaveabroadarrayofadvancedimagingtechnologies,theuseofwhichisencouragedbythedesiretoperformresearch.Additionally,academicexpertsareintenselyfocusedintheirareasofinterestandarekeenlyawareofthemultitudeofpossi-bleseriousresultsfromincidentalndings,alsopotentiallybi-asingtheirviewpoint.Therefore,inapproachingincidentalndingsinthisway,thereisariskthatratherthantheresultsofthisprojectlimitingtheoveruseofimaging,thedetailedguid-ancegeneratedfromthisprojecteithermightnotaffectsuchoverutilizationorcouldevenincreaseit.Ourgoalwasnotnec-essarilytoreduceutilization(althoughwebelievethisisneeded)butrathertooptimizeutilization.Inthisway,onlytheappro-priateincidentalndingsareevaluatedfurther.Thesefactorswereconsideredindesigningtheserecommendations,espe-ciallyregardingtheguidanceonthelengthandfrequencyoffollow-upstudiesforindeterminatelesions.REPORTINGCONSIDERATIONSSomeconsiderationsarecommontoallorgansystems.Oneuniversalprincipleistorefertoavailablepriorrele-vantimagingexaminationswheninterpretingincidentalndings.Priorexaminationsneednotbeofpreciselythesametypeormodalitybutareusefuliftheyincludetheanatomicareainquestion,suchasachestCTscanthatincludestheupperabdomen.Also,theapproachtoinci-dentalndingsshouldbeplacedinthecontextoftheindividualpatient’ssituation.Asanextremebutcom-monexample,theneedtoreportorpursueincidentalndingsmaybeunnecessaryinpatientswithseriousmedicalcomorbiditiesorlimitedlifeexpectancy.Thewordingoftheradiologyreportisalsocontroversialandcouldfallinto4categories.ThiscanbeillustratedthroughtheexampleofarenalmassthatseemstobeasimplecystonanunenhancedCTscan.Suchalesioncould1.Describedasa“low-attenuationmassstatisticallylikelytobeasimplecyst”ora“low-attenuationmasslikelytobebenign;”2.Reportedasa“renalcyst.”Thiscontainsthespecic,implicitrecommendationtodonothingandlimitsthelengthoftheradiologyreportbutmightbeinac-curateinasmallpercentageofsituations;3.Notreportedatall.Particularlyinthecaseofsmalllesions,somewouldarguethatsuchandingissocommonandinnocuousthatitdoesnotrisetothelevelofanabnormality.Refrainingfromreportingwouldbeanalogoustoanonradiologistphysiciannotmentioninganinsignicantskinlesiononaphysicalexaminationreport.Becausemanypatientsandsomephysiciansbecomeconcernedaboutevenminornd-ings,thiswouldpreventanyriskforfurthertesting;or4.Reportedbystatingthatadenitivediagnosiscannotbemade,buttherearenofeaturestosuggestamalignantetiology,withonepossiblephrasebeing“indeterminate,nomalignantfeatures.”Thiswouldleavetheworkuptothediscretionofthereferringphysicianandperhapsthepatient.However,suchareportleavesthereferrerinaquandary.Thismayleadtounnecessarytesting,butitwouldessentiallyacknowledgethelimitsoftheexami-nationandacknowledgethattherearenoevidence-baseddatatoallowspecicrecommendations.Option1wasconsideredacceptable,butnotnecessar-ilypreferred,byallmembersoftheIncidentalFindingsCommittee.However,thecommitteecouldnotreachaconsensusonallaspectsofthissubject,becausevariousmemberspreferred,whileothersraisedobjectionstoeachofoptions2,3,and4.Somemembersnotedthatreport-ingallincidentalndingscanbevaluableifapatienthasafollow-upexaminationandonlythereportisavailable.SCANNINGTECHNIQUESInthe4organ-specicsectionsbelow(kidneys,liver,adrenalglands,andpancreas),commentsapplytostan-dard–radiationdoseexaminations,whetherperformedunenhancedorenhanced.However,low-doseunen-hancedscansmaybeperformedforCTcolonography,identifyingurinarytractcalculiandotherapplications.Webelievethatincidentalndingsidentiedonsuchlow–radiationdose,unenhancedscansrequirespecialconsiderations.Theseareseparatelyaddressedinanad-ditionalsectionfollowingthe4organ-specicsections.NatureandScopeoftheProblemTheliteratureregardingtheapproachtorenalmassesde-tectedonrenalmass–protocolCTorMRIisrepletewithcaseseries,retrospectiveanalyses,andsuggestedclinicalguidelinesthathavebeenlongacceptedandarewidelyadoptedinclinicalpracticetodaytoday.Asummaryandupdateoftheseguidelines,discussedinthecontextofanBerlandetal/ManagingIncidentalomasonAbdominalCT incidentalnding,hasbeenrecentlydetaileddetailedandthusisnotentirelyrepeatedinthiswhitepaper.DetectionandCharacterizationArenalmasscanbefoundincidentally,eitheraspartofanexaminationthatallowsthemasstobefullycharac-terizedoraspartofanexaminationthatdoesnotallowthemasstobeevaluatedfully.Manyrenalmassescanbecharacterizedcompletelyusingultrasoundorcontrastmaterial–enhancedCT;however,somerenalmassesmayrequireadditionalimagingimaging.Renalmass–protocolCTorMRIexaminations(scansobtainedbothbeforeandafterintravenouscontrastmaterial)allowmostrenalmassestobefullycharacterized.Renalmassesaredividedintocysticandsolidtypes,andrecommenda-tionsaredetailedforeachandforboththegeneralpop-ulationandpatientswithcomorbiditiesorlimitedlifeexpectancy⠀Tables1).Ingeneral,thesuggestedman-agementofrenalmassesbeginsrstwithensuringthatthemassisnottheresultofanonneoplasticconditionthatcanmimicatumor.TheseconditionsincludepseudotumorssuchascolumnsofBertin,hypertrophiedtissueadjacenttoscars,vascularanomaliesandaneu-rysms,infarcts,andinfections.Focalbacterialpyelone-phritiscommonlycausesamasslikeabnormalityinthekidney.Also,fat-containingangiomyolipomasshouldbeTable1.Managementrecommendationsforpatientswithincidentalcysticrenalmasses ImagingFeaturesComorbiditiesorLimitedLifeExpectancy䦆Hairline-thinwall;nosepta,calcications,orsolidcomponents;waterattenuation;noIgnoreIgnoreIIFewhairline-thinseptawithorwithoutperceived(notmeasurable)enhancement;Ṯ攀calcicationorshortsegmentofslightlythickenedcalcicationinthewallorsepta;homogeneouslyhigh-attenuatingmasses3cm)thataresharplymarginatedanddonotIgnoreIgnoreIIFMultiplehairline-thinseptawithorwithoutperceived(notmeasurable)enhancement,minimalsmooththickeningofwallorseptathatmayshowperceived(notmeasureable)enhancement,calcicationmaybethickandnodularbutnomeasurableenhancementpresent;noenhancingsofttissuecomponents;intrarenalnonenhancinghigh-attenuationrenalmasses⠀3cm)꜀Observe§orignoreIIIThickenedirregularorsmoothwallsorsepta,withmeasurableenhancementSurgery‡Surgery‡orobserve§IVCriteriaofcategoryIII,butalsocontainingenhancingsofttissuecomponentsadjacenttoorseparatefromthewallorseptaSurgery‡Surgery‡orobserve§ Note:Theserecommendationsaretobefollowedonlyifnonneoplasticcausesofarenalmass(eg,infections)havebeenexcluded;seetextfordetails.Therecommendationsareofferedasgeneralguidanceanddonotnecessarilyapplytoallpatients.ReprintedwithpermissionfromRadiology2008;249:16-31.Inselectedpatients(eg,young),earlysurgicalinterventionmaybeconsidered,particularlyifaminimallyinvasiveapproach(eg,laparoscopicpartialnephrectomy)canbeused.†Whenamass1cmhastheappearanceofasimplecyst,furtherworkupisnotlikelytoyieldusefulinformation.‡Surgicaloptionsincludeopenorlaparoscopicnephrectomyandpartialnephrectomy;eachprovidesatissuediagnosis.Open,laparoscopic,andpercutaneousablationmaybeconsideredwhenavailable,butbiopsywouldbeneededtoachieveatissuediagnosis.Long-term(5-yearor10-year)resultsofablationarenotyetknown.§ComputedtomographyorMRIat6and12months,thenyearlyfor5years;theintervalanddurationofobservationmaybevaried(eg,longerintervalsmaybechosenifthemassisunchanged,longerdurationmaybechosenforgreaterassurance).Cysticmasses1.5cmthatarenotclearlysimplecystsorthatcannotbecharacterizedcompletelymaynotrequirefurtherevaluationinpatientswithcomorbiditiesandinpatientswithlimitedlifeexpectancy.ReprintedwithpermissionfromRadiology2008;249:16-31. JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 excluded.Withrareexceptions,amassthatcontainsfat,particularlywhennotcalcied,canbediagnosedasanangiomyolipomawithcondence.Thesubsequentman-agementthencanbederivedandissummarizedinbles1.ThesetablesarereconguredintheformofowchartalgorithmsinFigures1Theapproachtothecysticrenalmassfollowsthetime-testedapproachofBosniakBosniak.Theta-blesandowchartsareconstructedsothatbothpatientsinthegeneralpopulationandthosewithlimitedlifeexpectancycanbemanaged.Ingeneral,sizeisnotafactorintheBosniakclassicationofcysticrenalmasses,be-causelargecysticmassesareoftenbenign,andsmallonesmaybemalignant.However,thesmallerthemass,themorelikelyitisbenign.Therefore,thecommonlyen-counteredcystic-appearingrenalmassthatistoosmalltoevaluateallofitsfeatures,includingitsCTattenuation,canbepresumedtobebenignifitdoesnotdisplayanynonsimplefeatures.Inthegreen“actionboxes”intheowcharts⠀Figures1),observationwithimaging,alsoknownasactivesurveillancesurveillance,isrecom-mendedforindeterminatemassesinBosniakcategoryIIFandisalsoanoptionformassesincategoriesIIIandIVinpatientswithlimitedlifeexpectancyorcomorbidi-tiesthatwouldincreasetheriskoftreatment.Thereisnoknownintervaloftimethatcanbeusedtodiagnoseanindeterminaterenalmasswithcertainty,al-though5yearshasbeensuggestedasareasonablelengthoftimetodiagnoseanindeterminaterenalmassasbe-nignonthebasisofthelackofmorphologicchangechange.Dependingonthelevelofsuspicion,andpatientandreferrercomfortwithobservation,boththedurationandintervalmaybealtered.AsindicatedinTables1to3andtheowcharts⠀Figures1),growthalonecannotbeusedtodenitivelydiagnoseamass(whethersolidorcystic)asmalignant.Benignmassesmaygrow,andmalignantonesmaygrowlittle,ifatallall.Regardingtheowchartforcysticrenalmasses⠀),bothBosniakcategoryIIIandIVmassesaremanagedsurgically;however,categoryIVmasseshaveagreaterprobabilityofmalignancythancategoryIIImasses,andmanagementapproachesotherthanresectioncarrymorerisk.BecausemanyBosniakcategoryIIImassesarema-lignant,surgeryisrecommendedforthegeneralpopula-tion.PercutaneousbiopsyofBosniakcategoryIIIrenalmasses,althoughcontroversial,maybehelpful,particu-larlyinpatientswithcomorbiditiesthatwouldposerisktopatientsundergoingsurgerysurgery.Ifadenitivemalignantresultcanbeobtainedwithbiopsy,surgerymaybeplannedwithcondence.Forabenignbiopsyresulttobeuseful,itshouldbebothdenitiveandspe-cicofabenignentity.Biopsyresultsthatrevealnonspe-ciccellsshouldbeviewedwithcautionandcannotbeusedalonetoguidemanagement.BecauseBosniakcate-goryIIImassestypicallycontainfewsolidelements,itmaybedifculttobothtargetandprocurediagnosticTable2.Managementrecommendationsforincidentalsolidrenalmassesinpatientsinthegeneral MassSizeProbableDiagnosisRecommendationLarge⠀3cm)Renalcellcarcinoma†Surgery‡Angiomyolipomawithminimalfat,oncocytoma,otherbenignneoplasmsmaybefoundatSmall(1-3cm)Renalcellcarcinoma†Surgery‡Ifhyperattenuating,andhomogenouslyenhancing,considerMRIandpercutaneousbiopsytodiagnoseangiomyolipomawithminimalVerysmall⠀1cm)Renalcellcarcinoma,Observeuntil1捭꜀Thin⠀3mm)sectionshelpconrmenhancement Note:Theserecommendationsarebestfollowedafternonneoplasticcausesofarenalmass(eg,infections)havebeenexcluded;seetextfordetails.Therecommendationsareofferedasgeneralguidanceanddonotnecessarilyapplytoallpatients.Benignentitiesaremorelikelyinsmallrenalmassesthanlargeones.†ProvidedthereisnodetectablefatbyCTorMRIusingprotocolsdesignedtoevaluaterenalmasses.‡Surgicaloptionsincludeopenorlaparoscopicnephrectomyandpartialnephrectomy;bothprovideatissuediagnosis.Open,laparoscopic,andpercutaneousablationmaybeconsideredwhenavailable,butbiopsywouldbeneededtoachieveatissuediagnosis.Long-term(5-yearor10-year)resultsofablationarenotyetknown.§ComputedtomographyorMRIat3to6months,12months,andthenyearly;theintervalanddurationofobservationmaybevaried(eg,shorterintervalsifthemassisenlarging).ReprintedwithpermissionfromRadiology2008;249:16-31. Berlandetal/ManagingIncidentalomasonAbdominalCT tissueforbiopsy,limitingtheabilitytoachievedeni-tivelybenignormalignantresults.However,evenifacondentdiagnosisofabenignentitycanbemadeinthesepatients,observationisstillwarranted.Wedenesolidmassesasthosethatcontainlittleornouidattenuating⠀20Hounseldunits[HU])compo-nentsandusuallyconsistpredominantlyofenhancingtissueTables2Figure2).Asdescribedforcysticrenalmasses,allsolidmassesshouldbeevaluatedrstforfeaturessuggestinganonneoplasticetiology,suchasfocalbacterialpyelonephritisorotherconditionsnotedabove.AthoroughsearchforfatcellsusingCTorMRIprotocolsdesignedtoevaluaterenalmassesshouldalsobeundertaken.Althoughtherearerareexceptions,fat-containingnoncalciedrenalmassesinadultscanbediagnosedasbenignangiomyolipo-maswithcondencecondence.Thesubsequentapproachtoasolidrenalmassisthenpredicatedmostlyonsize.Althoughthereisnosinglefeatureofarenalmassthatcanbeusedtopredictitsbiologicbehavioraccurately,sizeisareasonableandpracticalapproach.Ingeneral,large⠀3cm)solidrenalmassesarelikelymalignant;similarly,thesmallerasolidmass,themorelikelyitisbenign.Inaddition,asmallrenalcellcarcinomaismorelikelytobelowgradeandindolentbehavingthanalargeroneone.Therefore,wehavesug-gestedthatsolidmasses1cmbeobservedobserved.Thisapproachisfurthersupportedbythedifcultyofconrm-ingthatmassesofthissizeareenhancingandarethereforesolid.Partialvolumeeffectscanmimicenhancement.Thus,theuseofthin-section⠀3mm)CTandMRIisadvisedwhenbothevaluatingandobservingsuchsmallmasses.However,therearerarecasesofaggressivelybehavingsmallrenalcellcarcinomas,eventhose1cm.Therefore,obser-vationisnotcompletelywithoutriskrisk.Solidrenalmassesbetween1and3cmcanbecharacter-izedasenhancingwithcondence.Unlikemasses1cm,thesemassesarelargeenoughtobetargetedforpercutane-ousbiopsy.Althoughstillsomewhatcontroversial,insomepatients,biopsycanbeusedtoprovideadenitivediagnosisofoncocytomaandangiomyolipoma,thetwomostcom-monbenignneoplasmsfoundaftersurgicalresectionofasolidrenalmassmass.Becauseanangiomyolipomawithminimalfattypicallypresentsasahyperdense,T2-hypoin-tense,homogeneouslyenhancingmass,MRI,withorwith-outCT,canbeusedtoidentifysuchmassesandleadtopercutaneousbiopsybiopsy.Althoughoncocytomasaretypicallyhomogeneouslyenhancingmassesandmaydisplayacentralscar,thesefeaturesmayalsobefoundinoncocyticrenalcellcarcinomas.Therefore,specicrecom-Table3.Managementrecommendationsforincidentalsolidrenalmassesinpatientswithlimitedlifeexpectancyorcomorbiditiesthatincreasetheriskoftreatment MassSizeProbableDiagnosisRecommendationLarge⠀3cm)RenalcellSurgery‡orobserveAngiomyolipomawithminimalfat,oncocytoma,otherbenignneoplasmsmaybefoundatsurgery;biopsycanbeusedpreoperativelytoconrmrenalcellcarcinomaSmall(1-3cm)RenalcellSurgery‡orobserveIfhyperattenuating,andhomogenouslyenhancing,considerMRIandpercutaneousbiopsytodiagnoseangiomyolipomawithminimalVerysmall⠀1cm)Renalcellcarcinoma,Observeuntil1.5捭꜀Thin⠀3mm)sectionshelpconrmenhancement Note:Theserecommendationsarebestfollowedafternonneoplasticcausesofarenalmass(eg,infections)havebeenexcluded;seetextfordetails.Therecommendationsareofferedasgeneralguidanceanddonotnecessarilyapplytoallpatients.Benignentitiesaremorelikelyinsmallrenalmassesthanlargeones.†ProvidedthereisnodetectablefatbyCTorMRIusingprotocolsdesignedtoevaluaterenalmasses.‡Surgicaloptionsincludeopenorlaparoscopicnephrectomyandpartialnephrectomy;bothprovideatissuediagnosis.Open,laparoscopic,andpercutaneousablationmaybeconsideredwhenavailable,butbiopsywouldbeneededtoachieveatissuediagnosis.Long-term(5-yearor10-year)resultsofablationarenotyetknown.§ComputedtomographyorMRIat3to6months,12months,andthenyearly;theintervalofobservationmaybevaried(eg,shorterintervalsifthemassisenlarging);thedurationofobservationmaybeindividualized.Observationmaybeconsideredforasolidrenalmassofanysizeinapatientwithlimitedlifeexpectancyorcomorbiditiesthatincreasetheriskoftreatment,particularlywhenthemassissmall.Itmaybesafetoobserveasolidrenalmassbeyond1.5cm,butthereareinsufcientdatatoprovidedenitiverecommendationsontherisksandbenetsofobservation.ReprintedwithpermissionfromRadiology2008;249:16-31. JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 mendationsastowhichmassesshouldundergopercutane-ousbiopsycannotbemade.NatureandScopeoftheProblemRecentadvancesinmultidetectorCT,MRI,ultrasoundand2-[F]uoro-2-deoxyglucosePEThaveledtothedetectionofincidentalhepaticmassesinboththeoncol-ogyandnononcologypatientpopulationthatinthepastremainedundiscovered.Thishasengenderedamanage-mentdilemmathatisparticularlypertinenttooncologypatients,inwhomanyhepaticmass,clinicalorsubclini-cal,warrantsattention.Atautopsy,asmanyas52%ofnoncancerpatientshavebenignhepaticlesions,andlivermetastasesarefoundinasmanyas36%ofpatientsdyingwithcancercancer.Keyquestionstoanswerincludethefollowing:(1)Doesthehepaticincidentalomaputthepatientatriskforanadverseoutcome?(2)Canaprimaryormetastaticmalignancybeaccuratelyandcondentlydifferentiatedfromabenignincidentaloma?and(3)Ifabenignlesion,mightitstillrequiresurgicalintervention,suchasresectingahepaticadenomatopreventrupture?ImplicationsofImagingandClinicalStrategiesforoptimizingthemanagementofthesele-sionsareonlybeginningtoemergeintermsofdecidingwhichoftheseincidentallivermassesmaynotneedfur-therevaluation,whichmaysimplybemonitoredovertime,andwhichrequiremoreaggressiveworkup.Preop-erativepercutaneousbiopsymayminimizediagnosticerrorbutisassociatedwithapostproceduralmorbidityof2.0%to4.8%andmortalityof0.05%0.05%.TheIncidentalFindingsCommittee’sguidanceformanagingliverincidentalndingsisillustratedin.Managingincidentalliverlesionsdependsontheprobableimportanceofthemass.Thisisassessedbothbytheappearanceofthemassandthelevelofriskthateachpatienthasfordevelopingimportantlivermasses.Im-portantlivermassesarenotlimitedtomalignancies.Forexample,abenignhepaticadenomamightrequiresurgi-calintervention.Thesecategoriesaredenedasfollows: 1 These recommendations are to be followed only if non-neoplastic causes of a renal mass (e.g., infections) have been excluded; see Ref. 48 for details. The recommendations are offered as general guidance and do not necessarily apply to all patients. See Table 1 for 2 When a mass smaller than 1 cm has the appearance of a simple cyst, further work-up is not likely to yield useful information. 3 Interval and duration of observation may be varied (e.g., longer intervals may be chosen if the mass is unchanged; longer duration may be chosen for greater assurance).4 In selected patients (e.g., young), early surgical intervention may be considered, particularly if a minimally invasive approach (e.g., laparoscopic partial nephrectomy) can be utilized.5 Morphologic change refers to change in feature characteristics, such as number of septations or their thickness. Growth should be noted, but by itself does not indicate malignancy.6 Surgical options include open or laparoscopic nephrectomy and partial nephrectomy; each provides a tissue diagnosis. Open, laparoscopic, and percutaneous ablation may be considered where available, but biopsy would be needed to achieve a tissue diagnosis. Long-term (5- or 10-year) results of ablation are not yet known.7 Limited life expectancy and co-morbidities that increase the risk of treatment.8 Cystic masses 1.5 cm or smaller that are not clearly simple cysts or that cannot be characterized completely may not require further evaluation in patients with co-morbidities and in patients with limited life expectancy.9 Percutaneous biopsy of Bosniak Category III masses may be considered, but may not be diagnostic. LEGEND Incidental Cystic Renal Mass Detected on CT Bosniak IIF No morphologic change Surgery Bosniak I or II Benignno further follow-up Limited life expectancy or co-morbidities General population Limited life expectancy or co-morbidities General population Surgery Further action based on change, life expectancy and co-morbidities Bosniak III or IV If follow-up appropriate,CT or MRI at 6 and 12 mo, then yearly for 5 yrs. 3, 8 CT or MRI at 6 and 12 mo, then yearly for 5 yrs. 3, 4 If follow-up appropriate,CT or MRI at 6 and 12 mo,then yearly for 5 yrs. 3, 9 Benignno further follow-up Morphologic change Morphologic change Surgery, follow-up or no further follow-up based on life expectancy and co-morbidities Fig1.FlowchartforincidentalcysticrenalmassdetectedonCT.Berlandetal/ManagingIncidentalomasonAbdominalCT 1.Low-riskindividuals:Youngpatients(aged40years),withnomalignancies,hepaticdysfunction,hepaticmalig-nantriskfactors,orsymptomsattributabletotheliver.2.Average-riskindividuals:Patientsaged40years,withnoknownmalignancies,hepaticdysfunction,hepaticmalig-nantriskfactors,orsymptomsattributabletotheliver.3.High-riskindividuals:Patientswithknownprimarymalignancieswithapropensitytometastasizetotheliver,cirrhosis,orotherhepaticriskfactors.Hepaticriskfactorsincludehepatitis,chronicactivehepati-tis,sclerosingcholangitis,primarybiliaryhemochromatosis,hemosiderosis,hepaticdysfunc-tion,andlong-termoralcontraceptiveuse.ADRENALGLANDSNatureandScopeoftheProblemAnincidentaladrenalmass,oftenreferredtoasanadre-nalincidentaloma,isdenedasanadrenalmass⠀1cm)discoveredincidentallyonacross-sectionalimagingex-aminationperformedforanotherreason.Incidentalad-renalmassesareverycommon,estimatedtooccurinapproximately3%to7%oftheadultpopulationpopulation63].Themostfrequentpathologyforanincidentallydiscoveredadrenalmassisanonhyperfunctioningade-ade-.Itwasshowninonestudythattheover-whelmingmajorityofincidentallydiscoveredadrenalmassesarebenigninpatientswithnoknownmalignan-malignan-.Statisticsindicatethatgiventhehighpreva-lenceofnonhyperfunctioningadrenaladenomasinthegeneralpopulation,anincidentallydiscoveredadrenalmassinanoncologypatientismostlikelybenign.How-ever,theadrenalglandisalsoacommonsiteformetas-tasesand,somewhatlesscommonly,primaryadrenaltumors,includingpheochromocytomas,aldosterono-mas,andadrenalcorticalcarcinomas.Thegoalofimagingwhenanincidentaladrenalmassisdiscoveredistodifferentiateabenign“leave-alone”mass(eg,nonhyperfunctioningtumor,myelo-lipoma,hemorrhage,cyst)fromamassthatwarrantstreatment(eg,metastasis,pheochromocytoma,adre-nalcorticalcarcinoma).Fromanimagingperspective,anoptimalalgorithmshouldbeusedtodiagnosebothleave-alonemassesandmassesthatneedtreatment,usingasfewtestsaspossible.TheadrenalowchartFigure4⤀andrecommendationsdescribedhereat- 1 These recommendations are to be followed only if non-neoplastic causes of a renal mass (e.g., infections and fat-containing angiomyolipomas) have been excluded; see Ref. 48 for details. The recommendations are offered as general guidance and do not necessarily apply to all patients.2 Differential diagnosis includes renal cell carcinoma, oncocytoma, angiomyolipoma. Benign entities are more likely in small renal masses than large ones.3 Limited life expectancy and co-morbidities that increase the risk of treatment.4 Interval and duration of observation may be varied (e.g., shorter interval if the mass is enlarging).5 Probable diagnosis renal cell carcinoma, provided there is no detectable fat at CT or MRI using protocols designed to evaluate renal masses. 6 If hyperattenuating and homogeneously enhancing, consider MRI and percutaneous biopsy to diagnose angiomyolipoma with minimal fat.7 Surgical options include open or laparoscopic nephrectomy and partial nephrectomy; both provide a tissue diagnosis. Open, laparoscopic, and percutaneous ablation may be considered where available, but biopsy would be needed to achieve a tissue diagnosis. Long-term (5- or 10-year) results of ablation are not yet known.8 Observation may be considered for a solid renal mass of any size in a patient with limited life expectancy or co-morbidities that increase the risk of treatment, particularly when the mass is small. It may be safe to observe a solid renal mass beyond 1.5 cm; however, there are insufficient data to provide definitive recommendations on the risks and benefits of observation. Thin ⠀9 Probable diagnosis renal cell carcinoma. Angiomyolipoma with minimal fat, oncocytoma, and other benign neoplasms may be found at surgery.10 Percutaneous biopsy can be utilized preoperatively to confirm renal cell carcinoma. LEGEND Incidental Solid Renal Mass Detected on CT 1-3 cm Surgery Surgery 7, 10 Follow-up m Limited life expectancy or co-morbidities General population General population Surgery Follow-up General population �3 cm Follow-up until 1 cm:CT or MRI at 3-6 mo and 12 mo, then yearly Follow-up until 1.5 cm:CT or MRI at 3-6 mo and 12 mo, then yearly Hyperattenuating, homogeneously enhancing: consider MRI, biopsy Limited life expectancy and co-morbidities Limited life expectancy and co-morbidities Fig2.FlowchartforincidentalsolidrenalmassdetectedonCT.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 tempttodoboth.Thealgorithmreectsthemostcommonlyencounteredimagingscenarios.However,itisimportanttonotethatthereareexceptionstosomeoftherecommendationsdependingonindivid-ualpatients’presentationsandhistories.Asnotedinothersectionsofthiswhitepaper,ifapatienthaslimitedlifeexpectancyorseverecomorbidities,workupofanincidentallydiscoveredadrenalmassmaynotbeappropriate.Readersarealsodirectedtoarecentcomprehensivereviewonthistopic Incidental Liver MassDetected on CT 0.5-1.5 cm �1.5 cm Follow-up Follow-up .5 cm Low attenuation, benign imaging features Low attenuation, suspicious imaging features Flash filling (robustly enhancing) Low attenuation, benign imaging features Benign diagnostic imaging features 8, 9 No benign diagnostic imaging features Low attenuation, suspicious imaging features Flash filling (robustly enhancing⤀ Low or average risk 1, 2 Any risk level 1, 2, 3 Any risk level 1, 2, 3 Low or average risk 1, 2 High risk Low risk Follow-up Evaluate Biopsy, core preferred Follow-upevaluate or biopsy, core preferred Average risk High risk 3 Benign, no further follow-up Benign, no further follow-up Benign, no further follow-up Benign, evaluate if FNH, adenoma8, 9 Evaluate Follow-up Benign, no further follow-up 8, 9 High risk 3 AB 1 Low risk individuals: Young patient (40 years old), with no known malignancy, hepatic dysfunction, hepatic malignant risk factors, or symptoms attributable to the liver.2 Average risk individuals:� Patient 40 years old, with no known malignancy, hepatic dysfunction, abnormal liver function tests or hepatic attributable to the liver.3 High risk individuals: Known primary malignancy with a propensity to metastasize to the liver, cirrhosis, and/or other hepatic risk factors. Hepatic risk factors include hepatitis, chronic active hepatitis, sclerosing cholangitis, primary biliary cirrhosis, hemochromatosis, hemosiderosis, oral contraceptive use, anabolic steroid use.4 Follow-up CT or MRI in 6 months. May need more frequent follow-up in some situations, such as a cirrhotic patient who is a liver transplant candidate.5 Benign imaging features: Typical hemangioma (see below), sharply marginated, homogeneous low attenuation (up to about 20 HU), no enhancement. May have sharp, but irregular 6 Benign low attenuation masses: Cyst, hemangioma, hamartoma, Von Meyenberg complex (bile duct hamartomas).7 Suspicious imaging features: Ill-defined margins, enhancement (more than about 20 HU), heterogeneous, enlargement. To evaluate, prefer multiphasic MRI.8 Hemangioma features: Nodular discontinuous peripheral enhancement with progressive enlargement of enhancing foci on subsequent phases. Nodule isodense with vessels, not parenchyma.9 Small robustly enhancing lesion in average risk, young patient: hemangioma, focal nodular hyperplasia (FNH), transient hepatic attenuation difference (THAD) flow artifact, and in average risk, older patient: hemangioma, THAD flow artifact. Other possible diagnoses: adenoma, arterio-venous malformation (AVM), nodular regenerative hyperplasia. Differentiation of FNH from adenoma important especially if larger than 4 cm and subcapsular.10 Hepatocellular or common metastatic enhancing malignancy: islet cell, neuroendocrine, carcinoid, renal cell carcinoma, melanoma, choriocarcinoma, sarcoma, breast, some pancreatic lesions. LEGEND Incidental Liver MassDetected on CT Fig3.FlowchartforincidentallivermassdetectedonCT.Berlandetal/ManagingIncidentalomasonAbdominalCT ImagingCharacterizationandWorkupIfanadrenalmasshasdiagnosticfeaturesofabenignlesionsuchasamyelolipoma(presenceofmacroscopicfat)orcyst(simplecyst-appearingwithoutenhance-ment),noadditionalworkuporfollow-upimagingisneeded.Ifthelesionis1to4cmandhasadensityofHUonCTorsignallosscomparedwiththespleenonout-of-phaseimagesofachemical-shiftMRI(CS-MRI)examination,itisalmostalwaysdiagnosticofalipid-richlipid-rich.Ifdiagnosticimagingfeaturesarenotpresentbuttheadrenalmasshasbeenstablefor1year,itislikelybenignbenign.Ifapatienthasnohistoryofcancer,therearenopriorexaminations,andthemasshasbenignimagingfeatures(lowdensity,homogeneouswithsmoothmargins),onemayconsiderafollow-upunenhancedCTorCS-MRIexaminationin12months.However,iftherearesuspi-ciousimagingfeaturesoncontrast-enhancedCT,suchasnecrosis,heterogeneousdensity,orirregularmargins,onecouldproceedwithanunenhancedCTorCS-MRIexamination.Ifthesedonotconrmthatthelesionisalipid-richadenoma,adrenalwashoutCTwith15-minutedelayedimagingtocalculatecontrastmaterialwashoutmaybehelpfulhelpful.Inpatientswithhistoriesofcancerandadrenalmasses,iftheimagingfeaturesarenotdiagnosticandthereisnopriorimagingtoconrmstability,onemayconsiderunenhancedCT,CS-MRI,orPETimagingimaging.Ifthemasscannotbediagnosedasalipid-richadenoma,adre-nalwashoutCTmaybehelpful.Inpatientswithnohistoriesofcancerandadrenalmasses4cm,onemayconsiderresection.Adenomastypicallyenhancerapidlyusingeitherio-dinatedcontrastmaterialorgadoliniumchelatesandalsodisplayrapidwashoutwashout.Althoughmetastasesgener-allyenhancerapidly,theirwashoutismoreprolonged.UsingCT,absolutepercentagewashoutvaluesarecalcu-latedusingtheformula(enhancedHUdelayedHU)/(enhancedHUunenhancedHU)100.Avalueof60%isdiagnosticofanadenoma.Relativepercentagewashoutisusedwhenanunen- If patient has clinical signs or symptoms of adrenal hyperfunction, consider biochemical evaluation Consider biochemical testing to exclude pheochromocytoma Benign imaging features = homogeneous, low density, smooth margins Suspicious imaging features = heterogeneous, necrosis, irregular margins APW = Absolute Percentage Washout RPW = Relative Percentage Washout CS-MR = Chemical Shift MRI F/U = Follow-up HU = Hounsfield Unit = decreased LEGEND Incidental Adrenal Mass 1 cm⤀Detected on CT or MR Imaging features not diagnostic 4 cm No history of cancer Benign imaging featuresPresume benign, consider 12 month F/U CT or MR Prior imaging Lesion enlarging Consider biopsy or resection Imaging features are diagnostic HU 10 or signal on CS-MR = adenoma Stable 1 year Benign Myelolipoma, ca++ = benign, no F/U No prior imagingHistory of cancer Suspicious imaging features Unenhanced CT or CS-MR HU 10 or no signal on CS-MR Adrenal washout CT APW / RPW 60/40% Adenoma 4 cm consider resection History of cancer: consider PET or biopsy Consider PET or below HU 10 or signal on CS-MR = adenoma APW / RPW 60/40% Biopsy if appropriateconsider CS-MR if not done No enhancement ( 10 HU)= cyst or hemorrhage Benign, no F/U Concerning for malignancyNo history of cancer: Fig4.FlowchartforincidentaladrenalmassdetectedonCTorMR.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 hancedCTvalueisnotavailableandtheenhancedvaluesarecomparedwith15-minutedelayedscans.Relativepercentagewashoutiscalculatedusingtheformula(en-hancedHU15-minutedelayedHU)/enhancedHU100;avalueof40%isdiagnosticforanadenomaadenoma.AdrenalwashoutCTwasusedsuccessfullytodistinguishadenomasfromnonadenomasin160of166adrenalmasseswith98%sensitivityand92%specic-specic-.RecentadvancesinimagingcharacterizationwithCT,MRI,andPEThavedecreasedtheneedforim-age-guidedpercutaneousbiopsiestocharacterizead-renalmassesmasses.However,ifanadrenalmassisen-larging,itmaybeprudenttoproceedtopercutaneousadrenalbiopsyorsurgicalresection.Inanoncologypatient,anewadrenalmassinapatientwithknownmetastaseselsewhereismostlikelyanothermetastasis.However,anisolatedadrenalmasscouldbebenignormalignant.IfthemasscannotbecharacterizedasanadenomausingCT,MRI,orPET,abiopsymaybeappropriate.Iftherearesignsorsymptomsofpheo-chromocytoma,itmaybeprudenttoobtainplasma-fractionatedmetanephrineandnormetanephrinelev-elsbeforebiopsybiopsy.Imagingexaminationsareusefultoseparateadrenaladenomasfromothermassesbutcannotbeusedtodis-tinguishhyperfunctioningadenomasfromnonhyper-functioningadenomas.Oneapproachwouldbetorelyonhistoryandphysicalexaminationtodeterminewhichpatientsshouldundergobiochemicaltestingforhyper-functioningadrenalneoplasms.Someendocrinologistsrecommendexcludinganoccult,asymptomatichyper-functioningneoplasminalladrenalincidentalomasincidentalomas.Thisapproachwouldbecostlyandisnotroutinelyperformedbymanyphysicians.Regardingtheradiologyreport,whenanadenomacanbediagnosedwithimaging,wesuggeststating,“Findingsconsistentwithabenignadenoma.Ifthereareclinicalsignsorsymptomsofadrenalhyperfunction,biochemicalevalu-ationmaybeappropriate.”NatureandScopeoftheProblemThefrequencyofdetectionofpancreaticcystsbyCTscan-ningisreportedbetween1.2%1.2%and2.6%2.6%.ForMRI,thereportedfrequencyissignicantlyhigher,at19.9%ofMRIexaminationsexaminations.Becausepancreaticcystsarequiteprevalent,apracticingradiologistmayseeseveralforevery100abdominalimagingcasesperformed.Cysticpancreatictumorsaremostoftenfranklybe-nignorlow-gradeindolentneoplasms.Inonestudythatincludedasymptomaticpatientswithpancreaticcystsinwhomtherewasoperativecorrelation,17%ofasymp-tomaticcystswereserouscystadenomas,28%weremu-cinouscysticneoplasms,27%wereintraductalpapillarymucinousneoplasms(IPMNs),2.5%wereductaladeno-carcinomas,and3.8%werepseudocystspseudocysts.Intraduc-talpapillarymucinousneoplasmswerethemostcom-moncysticneoplasmwhenbothsymptomaticandasymptomaticpatientswereevaluated.Inanotherseries,39%ofIPMNswereincidentallydetected,and50%ofIPMNsweresidebranchorbranchductIPMNswitha5-yearriskfordevelopinghigh-gradedysplasiaorinva-sivecarcinomaof15%15%.Mucinouscysticmasses,namelyIPMNsandmuci-nouscysticneoplasms,haveawell-establishedmalignantpotentiallikenedtoanadenoma-carcinomasequencesequence.Becauseofthismalignantpotential,ithasbecomeincreasinglydifcultforradiologistsevaluatingindivid-ualcasestoknowhowtoframethereporttohelpguideappropriatemanagement.Webelievethattheguida-ncebelowwillhelpintheevaluationandreportingofthemajorityoftheselesions.TheserecommendationsarealsosummarizedinFigure5DetectionandCharacterizationThisdiscussionislimitedtounexpectedpancreaticcystsinasymptomaticpatients.Asymptomaticpatientshavenoclinicalorlaboratoryindicationdirectlyreferabletothepancreas,includingbutnotlimitedtohyperamy-lasemia,recent-onsetdiabetes,severeepigastricpain,weightloss,orjaundice.Themostfrequentlydetectedcystis10mminsizesize.Cystsofthissizearepartic-ularlyprevalentonMRI.Imagingwillnotbeabletocharacterizetheselesions.Thequestionofappropriatefollow-upissubsequentlyaddressed.Thereisampleliteraturetosupportthenonsurgicalman-agementofpancreaticcysts3cmthatdonotdisplay“worrisomefeatures”features”.Somerecommend2.5cmasamaximaldiameterfornonsurgicalmanagementmanagement.Worrisomefeaturesincludelargersize,presenceofmuralnodules,dilationofthecommonbileduct,involvementofthemainpancreaticduct,andlymphadenopathylymphadenopathy.StudiesofpatientsinwhomcystshavebeenresectedoraspiratedṮ搀thatmalignancyorpremalignancydoesnotcorrelatewithcystsizealone.Thesestudiessuggestthatmucinouslesionsofanysizearepremalignantpremalignant.However,inaseriesof170of539patientswhounderwentoperativeresectionofpancreaticcysts,noinvasivecancerswerefoundinmucinouscysts3cmm.Nevertheless,establishingacystasmucinousisimpor-tantbecauseoftheirhigherriskforthepresenceorfuturedevelopmentofmalignancy.Morphologicfeaturesthataidindiagnosisofamucinoustumorinclude(1)thepresenceorabsenceofseptae(mucinouscysticneoplasmsgenerallyaremultilocular,withlargecysts),(2)theposi-tionofcalcication(mucinouscysticneoplasmstypicallyBerlandetal/ManagingIncidentalomasonAbdominalCT haveperipheralcalcication,whereasseroustumorshavecentralcalcication),(3)locationwithinthepancreas,and(4)thepresenceofmainpancreaticductinvolve-involve-.Mucinouscystictumorscanbesus-pectedwhenacystispresentinthetailofthepancreasinaperimenopausalwomanwoman.Thepresenceorabsenceofdirectcommunicationwiththemainpancreaticductmustbeestablishedtodistinguishamucinouscystictu-mor(withrelativelyhighmalignantpotential)fromabranchductIPMN(withrelativelylowmalignantpoten-tial).Three-dimensionalimagingwitheitherMRIorCTcanaddressthisquestion.Conversely,serouscystade-nomacharacteristicallydisplaysvariablydenseradialsep-taeinahoneycombedorspongiformpatternandcentralcalcication.Themoreperipheralcystsarelargerthanthemorecentralcysts.Asimplebutusefulimaging-basedclassicationsys-temdifferentiatespancreaticcysticmassesinto4mor-phologictypes:(1)unilocular(pseudocysts,mucinouscysticneoplasms,lymphoepithelialcysts,smallIPMNs,andsmallseroustumors),(2)microcystic(serouscysta-denomasandlymphoepithelialcysts),(3)macrocystic(mucinouscysticneoplasms,oligocysticseroustumors,andIPMNs)and(4)cystswithsolidcomponents(solid-appearingseroustumors,solidpseudopapillaryneo-plasms,andcysticisletcelltumors)tumors).ImplicationsofImagingandClinicalMostincidentalcystscanbedetectedonroutineabdom-inalstudies.However,ifacystneedstobecharacterized,itisrecommendedthatadiagnosisofaspeciccysttypenotbemadeunlessthepatientundergoesadedicated“pancreas-style”study.FormultidetectorCT,thiswouldrequireadual-phasecontrast-enhancedacquisitioninbothpancreaticandportalvenousphasesusinganarrowdetectorconguration.Thin-sectionimagesshouldbeavailableonaworkstationthatcanperform3-Danalysis.Magneticresonanceimagingshouldbeperformedat1.5T.Phased-arraytorsocoilsenhancesignalandparal-lelimagingincreasesspeedandimprovesresolution.Thestudyshouldincludesequencesthatdisplayin-phaseandout-of-phaseT1,T2(preferablywithfatsuppression),and3-D,fat-saturated,gradient-echoT1gadolinium-enhancedsequencesinpancreatic,portal,andequilib-riumphases.Additionally,MRcholangiopancreatogra- 1 Signs and symptoms include hyperamylasemia, recent onset diabetes, severe epigastric pain, weight loss, steatorrhea or jaundice.2 Consider decreasing interval if younger, omitting with limited life expectancy. Recommend limited T2-weighted MRI for routine follow-ups.3 Recommend pancreas-dedicated MRI with MRCP.4 If no growth after 2 years, follow yearly. If growth OR suspicious features develop, consider resection.5 BD-IPMN = branch duct intraductal papillary mucinous neoplasm. LEGEND cm Stable Growth 2-3 cm �3 cm Uncharacterized cystic mass BD-IPMN Serous cystadenoma Serous cystadenoma Uncharacterized cystic mass or other cystic neoplasm Single follow-up in 1 yr, preferably MRI Follow-up yearly Follow-up every 6 mo for 2 years Follow-up every Consider resection when 4 cm Cyst aspiration Resect, depending on co-morbidities Imaging characterization, preferably MRI/MRCP Asymptomatic Patient with Incidental Pancreatic Cystic MassDetected on CT, MRI (with or without contrast) or US Benign, no further follow-up Fig5.FlowchartforanasymptomaticpatientwithanincidentalpancreaticcysticmassdetectedonCT,MRI(withorwithoutcontrast),orultrasound(US).MRCPMRcholangiopancreatography.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 phyisnecessary.CurrentMRIscannershaverespiratorytriggered3-DsequencesforMRcholangiopancreatogra-cholangiopancreatogra-.Secretinadministrationmayfacilitatevisual-izationofthecommunicationofacystwiththemainpancreaticductduct.Byconsensus,theIncidentalFindingsCommitteesuggestsdedicatedMRIastheim-agingprocedureofchoicetocharacterizeapancreaticcyst.ThisreectsthesuperiorcontrastresolutionofMRI,facilitatingtherecognitionofseptae,nodules,andductcommunicationcommunication.Thepretestlikelihoodthatagivenlesioninanindi-vidualpatientisamalignantneoplasmisofparamountconsiderationwhendecidingonmanagement.Contro-versyexistsbetweenusingdedicatedimagingoranat-temptataspirationofacystunderendoscopicultrasoundguidance.Mostoften,thisdecisionwillbemadeonthebasisofthesizeofthecyst,locationwithinthepancreas,accessibilitytotheendoscopicultrasoundapproach,andexpertiseoftheendosonographer.Acarcinoembryonicantigenlevelintheaspirateof192ng/mLhasahighspecicityfordiscriminatingmucinousfromnonmuci-nouscysts,demonstratinghigheraccuracythancystmor-mor-.Amylaselevelsof250U/Lexcludepseudocysts.Thereisahighdegreeofoverlapbetweenthevaluesobtainedataspirationaspiration.Recentreportshavedocumentedthedevelopmentofductaladenocarci-nomainaremotesiteinthepancreasfromanIPMNIPMN.Manybelievethatthepresenceofamucinouslesionisasignalofincreasedriskforpancreaticneoplasmanywherewithinthegland.TheconsensusoftheIncidentalFindingsCommitteeisthatifsurgeryiscontemplated,aspirationofapancre-aticcyst3cmshouldbeattempted.Itisawidelyheldopinion,sharedbythiscommittee,thatcysts1.5cmneednotbeimmediatelycharacterized,whereasitisap-propriatetocharacterizeothercysts,dependingonco-morbidconditionsandlifeexpectancy.Imagingsurveillanceofpancreaticcysticneoplasmsiscontroversial.However,emergingconsensussuggeststhatselectivenonoperativemanagementinpatientswithincidentalpancreaticcystsisappropriateappropriate.Inaseriesof369of539patientswithameanradio-graphicfollow-upperiodof24months(range,1-172months),8%developedchangesthatpromptedresec-tion.Malignancieswerepresentin38%38%.Inaretro-spectivecaseseriesof79patientswithlong-termfollow-up,either5yearsbyimagingor8yearsclinically,diagnosedwithsmall⠀2cm),simplepancreaticcystsonsonographyorCTfrom1985to1996werereviewed.Ofthe22patientswithradiologicfollow-up,59%hadcyststhatremainedunchangedorbecamesmaller(meansize,8mm;meanfollow-upperiod,9years),and41%hadcyststhatenlarged,fromameanof14mmtoameanof26mm(meanfollow-upperiod,8years).Ofthe27patientswithclinicalorquestionnairefollow-up(meanfollow-upperiod,10years),nonedevelopedsymptom-aticpancreaticdisease.Twenty-threepercentdiedwithin8yearswithoutadequateradiologicfollow-up,noneofpancreas-relatedcausescauses.Anotherseriesof90pa-tientswithincidentalcystswithameanfollow-upperiodof48monthsrevealedmalignancyin1patient7yearsfromdiagnosisdiagnosis.Thefrequencyofcancerinsurgi-callyresectedcysts3cmhasbeenreportedas19%(includingsymptomaticandasymptomaticpatients)patients),butwhenonlytrulyincidentalcystsareevaluated,thefrequencyisreportedasonly3.5%3.5%.Afollow-upexaminationmustclearlyestablishthestabilityofacyst.Therefore,patientsshouldbeadvisedtoundergoserialimagingatfacilitieswithprotocolsfordedicatedpancreaticimaging.Althoughthereisnoclearconsensusamongpancreaticexpertsregardingtheopti-malimagingtestforfollow-upofpancreaticcysts,alim-itedMRIexaminationrelyingexclusivelyonT2-weightedunenhancedacquisitionshasbeenproposedasapracticalfollow-upstrategystrategy.Carefulevaluationoftheimagingndingsisdirectedatinspectingthelesionforchangesinthethicknessofthewall,muralirregularities,orfranksolidnodules.ForbranchductIPMNs,theadjacentmainpancreaticductdiametershouldberecorded.Thelesionshouldbecarefullymeasuredwithslicenumberandseriesappearinginthereport,andelec-troniccalipersshouldbeplacedontheexactimageusedtodeterminethediameters.Currently,thereisnoconsensusondeningwhatincrementofgrowthisimportant.Itiswellknownthattheprecisionofmanualmeasurementisinverselyrelatedtothelesiondiameter.Thus,itmaybedifculttodetermineifthereportedgrowthofasmalllesionistruegrowthormeasurementerror.Asofthiswriting,thereisnouniversallyacceptedfol-low-upprotocol.MostproposedprogramsarebasedontheSendaicriteriathatarosefromaconsensusconferencead-dressingthemanagementandfollow-upofmucinouspan-creaticcysts.Cysts1cmarefollowedyearly,cystsbetween1and3cmaresentforfurtherimaging(endoscopicultra-soundorMRI)lookingforseptaeandmuralnodules,andsimplecystsarefollowedat6-monthintervalsfor2yearsandthenyearly.Iftheygrowabove3cmordevelopanyworrisomefeatures,patientsareconsideredcandidatesforfor.Incontradistinction,arecommendationde-rivedfromreviewing166cystswithameansizeof2cmin150patientsrevealedthat89%showednogrowthover2years.Theonlypredictorofcystgrowthwasthepresenceofmuralnodules.Thisstudysuggestednofollow-upuntil2yearsafterdetectiondetection.IntheIncidentalFindingsCom-mittee’srecommendations,cysts2cmmaybefollowedat1-yearintervals,andifthereisnogrowth,follow-upceasesifthepatientremainsasymptomatic.Acystthatis3cmisconsideredasurgicallesionunlessitisaserouscystadenomaBerlandetal/ManagingIncidentalomasonAbdominalCT orifpatientcomorbiditiesprecludebenetfromresection.Acystbetween2and3cmmaybecharacterizedandfol-lowedsemiannuallyifmucinous,yearlyifuncharacterized,andevery2yearsifitisaserouscystadenoma.Serouscystadenomaisabenignlesion.However,studieshaveclearlydocumentedthattheselesionsmaygrow.Therefore,somerecommendresectingserouscystadenomas4cmregardlessofthepresenceofsymptomssymptoms,orinsymptomaticpatientsregardlessofsizesize.Solidpseudo-papillaryepithelialneoplasmisalow-grademalignancythatcanpresentwithcystic-appearingcomponents.Themajor-ityarefoundinyoungwomen.Theyfrequentlycontainperipheralcalcicationandvariablecontent(mostcharac-teristicallyhemorrhages)withinthecysts.Solidpseudopap-illaryepithelialneoplasmlesionsshouldundergoresection.TheIncidentalFindingsCommitteerecommendsthefollowingformanagingincidentalpancreaticcysts:1.Surgeryshouldbeconsideredforpatientswithcysts3cm.a.Ifthelesionisaserouscystadenoma,surgeryisdeferreduntilthecystis4cm.b.Solidpseudopapillaryepithelialneoplasmtumorsshouldberesected.c.Patientfactorsultimatelydeterminetheappropri-atenessofsurgicaltreatment.2.Patientswithsimple(notcontaininganysolidele-ments)cysts3cmcanbefollowed.a.Attemptsshouldbemadetocharacterizeallcysts2cmatthetimeofdetection.Magneticreso-nanceimagingistheimagingprocedureofchoice.b.Cystaspirationisstronglyadvisedbeforeanysurgeryisundertakeninapatientwithacystofthissize.c.Cysts2cmcanbefollowedlessfrequentlythanthosebetween2and3cm.d.Avoidcharacterizingcysts1.5to2cmunlessabsolutelycharacteristic.3.Thepresenceofsymptomsisacriticalfactorindecid-ingappropriatetherapy.a.Thefrequencyofmalignancyinsmallcystsissig-nicantlyhigherinsymptomaticpatients.SPECIALCONSIDERATIONSFORLOW-DOSEUNENHANCEDCTBecauseoftheadventofscreeningCTexaminationssuchasCTcolonographyandheightenedconcernaboutradi-ationexposure,low-doseunenhancedCTexaminationsoftheabdomenareincreasinginuse.Themanagementofincidentalndingsdiscoveredeitheronsuchexamina-tionsoronconventional-doseunenhancedexaminationsiscontroversial,andtherearedifferentchallenges.Low-dosetechniqueswillincreaseimagenoisebutshouldnotchangethemeanHUvaluestodetermineadrenalmassdensity.Thefollowingsectionsdescribeorgan-specicapproachesforthesetypesofexaminationsthatmayvaryfromthosedescribedabove.Themanagementofarenalmassdetectedonanunen-hancedCTscaniscontroversial.Tothebestofourknowledge,nostudieshaveaddressedhowbesttoman-agenon-fat-containingrenalmassesdetectedwithunen-hancedCT,andthus,theserecommendationsreectouropinionsonthebasisofourexperienceandunderstand-ingoftheprevalenceandnaturalhistoryofsuchndings.Furthermore,otherthanangiomyolipomas,renalmassesdetectedincidentallyonunenhancedCTscansoftencannotbeaccuratelycharacterized.OurexperiencesuggeststhatwhenarenalmassseemstobeasimplecystonanunenhancedCTscan,thechancethatthemassisbenignisextremelyhigh.However,carefuleval-uationofthemass’sfeaturesisimportant.TobeconsideredaprobablesimplecystonunenhancedCT,themassshouldbewellmarginated,containcontentsthatarehomoge-neous,andwaterattenuation(0-20HU),anddisplaynosepta,wallthickening,calcication(unlessminimal,thincalcicationwithinthewall),ornodularity.Ifanyoftheselatterfeaturesispresent,arenalmass–protocolCTorMRIwouldbeneededtodiagnosethemasswithcompletecon-dence.Sonographymaybehelpful,butinsomecasesitmaynotbedenitive.Toourknowledge,nostudiesintheliteraturehavespe-cicallyaddressedthelikelihoodofcancersinlesionsthatseemtobesimplecystsonunenhancedCT.Furthermore,whenlow-doseCTtechniquesareused,nonsimple(andpotentiallymalignant)featuresthatotherwisewouldbede-tectedwithstandard-doseCTmaynotbedetectable.Asatheoreticalexample,theheterogeneityofarenalcellcarci-nomamaybeincorrectlyattributedtonoiseoflow-doseCTandundergonofurtherevaluationorfollow-up.Also,somesimplecystsmaynotappearhomogeneous,becauseofnoise,sodifferentiatingheterogeneitysometimesencoun-teredonlow-doseCTfromaheterogeneoussolidmassmaybedifcult.Hence,althoughthepossibilityofmisinterpret-ingarenalcancerasasimplecystexists,itiswellunderstoodthatthetechnicalfactorsusedtoperformanexaminationaffectsensitivityandspecicity.TheIncidentalFindingsCommitteerecommendsthefollowingforlow-doseunenhancedCTexaminationsforrenalmasses:1.Itmaybeappropriatetointerpretincidentalrenalmassesassimplecystsunlesssuspiciousfeaturesnotedaboveareconvincinglypresent.Theargumentforadoptingthisapproachisevenstrongerwhenconsid-JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 eringsmall⠀3cm)masses,particularlythosecm.Thesmallerthemass(evenwhensolid),themorelikelyitisbenign.Furthermore,masses1cmmaynotbeabletobefullycharacterized,evenifrenalmass–protocolCTorMRIwasperformed.Althoughthisrepresentsaconsensusopinionofthecommittee,nodataareyetavailabletosupportthisapproach.2.Ifarenalmassissmall⠀3cm),homogeneous,and70HU,recentdatasuggestthatthemasscanbecondentlydiagnosedasabenignhyperattenuatingcyst(BosniakcategoryII)II).LiverTherecommendationsintheowchartinFigure3tolow-doseunenhancedproceduresaswellasstandard–radiationdoseenhancedexaminations.TheIncidentalFindingsCommitteerecommendsthefollowingforlow-doseunenhancedCTexaminationsforlivermasses:1.Inlow-riskandaverage-riskpatients,sharplymargin-ated,low-attenuation⠀20HU)solitaryormultiplemassesmaytypicallynotneedfurtherevaluation.2.Small,solitarymasses1.5cmthatarenotcysticandarediscoveredonunenhancedorstandard-doseorlow-dosescansinlow-riskandaverage-riskpatientsmaytypicallynotneedfurtherevaluation.AdrenalGlandsThelow-doseunenhancedtechniqueislesssensitivefordeterminingtheinternalarchitectureandheterogeneityofanadrenalmassthancontrast-enhancedCTwithastandardradiationexposure.Wearenotawareofanyhelpfulliteratureaddressingthetopicofadrenalmasscharacterizationonlow-doseunenhancedCTexamina-tions.Therefore,theserecommendationsrepresenttheconsensusopiniononthebasisoftheclinicalexperienceofthecommitteemembers.TheIncidentalFindingsCommitteerecommendsthefollowingforlow-doseunenhancedCTexaminationsforadrenalmasses:1.Becauseattenuationshouldnotbealteredbyalow-dosetechnique,ifthemeanattenuationofanadrenalmassis10HUonalow-doseCTexamination,onemayconcludethattheadrenalmassislikelytobeabenignadenoma.2.Ifalesionis10HUand1to4cminanasymptom-aticpatientwithoutcancer,1-yearfollow-upCTorMRImaybeconsidered,ifnopriorstudiesforcom-parisonareavailable.Priorexaminationsthatshowstabilityfor1yearcaneliminatetheneedforfurtherworkup,soeveryeffortshouldbemadetoobtainpriorCTorMRIexaminationsinthesesituations.3.Foradrenalmasses4cm,dedicatedadrenalMRIorCTshouldbeconsideredtofurthercharacterize.TherecommendationsshowninthepancreaticowchartFigure5⤀alsoapplytolow-doseunenhancedCTexamina-tions.TheimportanceofcomparisonwithpriorCTorMRIexaminationscannotbeoveremphasizedtopotentiallyavoidfurtherworkup.Specically,forlesions2cm,sta-bilityover1yearishighlysuggestiveofabenignlesionandmayeliminatetheneedforfollow-upimaging.FUTURECOMMITTEEOBJECTIVESTheIncidentalFindingsCommitteehopesthattheserecommendationswillbecomewidelyappliedandwillsearchforadditionalmethodstodisseminatethem.Thecommitteealsoexpectstoreneandadapttheserecom-mendationsandtodevelopadditionalguidanceforothertypesofincidentalndings.Toadvancethescienticevidenceregardingincidentalndings,thecommitteerecommendsthattheconcepts,terminology,andparam-etersdiscussedinthispaperbecomethebasisforfutureresearch,tohelptheresultsofsuchresearchbemoreeasilyappliedwithinacommonframework.IncidentalndingsonimagingduringdailypracticehavegrowninnumberrelatedtotherapidincreaseintheutilizationofCTandtoitsimprovedimagequality.Theseincidentalndingspotentiallyleadtoincreasedrisktothepatientandcostfromadditionalprocedures.Underscoringconcernamongphysiciansisthefearthatfailuretoreportincidentalndingsandrecommendfollow-upwillplaceradiologistsinjeopardyformalpracticelitigation,shouldalesioneventuallyleadtoalife-threateninghealthproblem.ThiseffortwithintheACR,conductedbytheInci-dentalFindingsCommittee,attemptstosystematicallydescribeavarietyofthemostcommonpotentialinciden-talndingsonabdominalCTandprovidedetailedrec-ommendationstoassistpracticingradiologistsinmakinginformeddecisionsaboutreportingsuchmassesandadvisingtheirreferringcliniciansandpatientsaboutwhetherandhowtheseshouldbemanaged.Thisispartofanongoingprojecttodevelop,rene,anddisseminateinformationaboutincidentalndingsandtocollectin-formationandsupportresearchaboutthem.ToN.ReedDunnick,MD,whosupportedandhelpedestablishtheCommitteewithintheBodyImagingCom-missionoftheACRandtoDavidKurthoftheACRstaff,Berlandetal/ManagingIncidentalomasonAbdominalCT 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sGY,RattnerDW,Fernán-dez-delCastilloC.Serouscystadenomaofthepancreas:tumorgrowthratesandrecommendationsfortreatment.AnnSurg2005;242:413-21.CommitteeMembersIncidentalFindingsCommittee:LincolnL.Berland,MD,chair.KidneySubcommittee:StuartG.Silverman,MD,chair,JoelF.Platt,MD,BrianR.Herts,MD,andGaryM.Israel,MD.LiverSubcommittee:RichardM.Gore,MD,chair,MichaelP.Federle,MD,MarkE.Baker,MD,andW.DennisFoley,MD.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 AdrenalGlandSubcommittee:WilliamW.Mayo-Smith,MD,chair,JoelF.Platt,MD,BrianR.Herts,MD,GlennA.Krinsky,MD,andIsaacR.Francis,MD.PancreasSubcommittee:AlecJ.Megibow,MD,MPH,chair,RichardM.Gore,MD,MarkE.Baker,MD,andAndrewJ.Taylor,MD.LexiconSubcommittee:LincolnL.Berland,MD,chair,WilliamP.Shuman,MD,StuartG.Silver-man,MD,andAlecJ.Megibow,MD,MPH.ACRColonColonographyCommittee:JudyYee,MD,chair.ExOfcio:JamesA.Brink,MD,chair,BodyImaging Toaccessthearticleandtaketheexam,logintoandclickontheCMEiconlocatednexttothecover.Followtheinstructionsandanswer3questionstocompletetherequirementforCME.ClaimthecreditandprintyourCMEcerticateNote:CMEforACRmembersisfree,howeveryouwillneedtoclickonthe“BuyNow”buttonandproceedthroughtheshoppingcartprocessinordertoreceivethecredit.AccreditationStatementTheAmericanRoentgenRaySocietyisaccreditedbytheAccreditationCouncilonContinuingMedicalEducationtoprovidecontinuingmedicaleducationforphysicians.DesignationStatementTheAmericanRoentgenRaySocietydesignatesthiseducationalactivityforamaximumofAMAPRACategory1Credit(S)™.Physiciansshouldonlyclaimcreditcommensuratewiththeextentoftheirparticipationintheactivity.TheAmericanMedicalAssociationhasdeterminedthatphysiciansnotlicensedintheU.S.whoparticipateinthisCMEactivityareeligibleforAMAPRACategory1Credit(S)™TheAmericanRoentgenRaySocietyisastrategicpartneroftheAmericanCollegeofFacultyDisclosureStatementsThefacultymemberslistedbelowhaveindicatedthattheyhavenorelevantnancialrelation-shipsorpotentialconictsofinterestrelatedtothematerialpresented,andtheydonotdiscusstheuseofamedicaldeviceorpharmaceuticalthatisclassiedbytheFDAasinvestigationalfortheintendeduse,orthatis“off-label,”e.g.,ausenotdescribedontheproduct’slabel.RichardM.Gore,MDWilliamW.Mayo-Smith,MDAlecJ.Megibow,MD,MPHJamesA.Brink,MDMichaelP.Federle,MDIssacR.Francis,MDBrianR.Herts,MDGaryM.Israel,MDGlennKrinsky,MDJoelF.Platt,MDAndrewJ.Taylor,MDThefacultymemberslistedbelowhavedisclosedthefollowingnancialrelationshipandtherearenoconictsofinterestrelatedtotheirmaterial,andtheydonotdiscusstheuseofamedicaldeviceorpharmaceuticalthatisclassiedbytheFDAasinvestigationalfortheintendeduse,orthatis“off-label,”:e.g.,ausenotdescribedintheproduct’slabel.LincolnL.Berland,MD-Consultant,Nuance,Inc.StuartG.Silverman,MD-BookRoyalties,Lippincott,Williams,&WilkinsJudyYee,MD-ResearchGrant,GEHealthcareMarkE.Baker,MD-InformalConsultantonVolumen,Bracco;ResearchAgreement,Siemen’sMedicalSystemsW.DennisFoley,MD-MedicalAdvisoryBoardHonorarium,GEHealthcareWilliamP.Shuman,MD-ClinicalResearchGrant,GEHealthcare Berlandetal/ManagingIncidentalomasonAbdominalCT AdrenalGlandSubcommittee:WilliamW.Mayo-Smith,MD,chair,JoelF.Platt,MD,BrianR.Herts,MD,GlennA.Krinsky,MD,andIsaacR.Francis,MD.PancreasSubcommittee:AlecJ.Megibow,MD,MPH,chair,RichardM.Gore,MD,MarkE.Baker,MD,andAndrewJ.Taylor,MD.LexiconSubcommittee:LincolnL.Berland,MD,chair,WilliamP.Shuman,MD,StuartG.Silver-man,MD,andAlecJ.Megibow,MD,MPH.ACRColonColonographyCommittee:JudyYee,MD,chair.ExOfcio:JamesA.Brink,MD,chair,BodyImaging Toaccessthearticleandtaketheexam,logintoandclickontheCMEiconlocatednexttothecover.Followtheinstructionsandanswer3questionstocompletetherequirementforCME.ClaimthecreditandprintyourCMEcerticateNote:CMEforACRmembersisfree,howeveryouwillneedtoclickonthe“BuyNow”buttonandproceedthroughtheshoppingcartprocessinordertoreceivethecredit.AccreditationStatementTheAmericanRoentgenRaySocietyisaccreditedbytheAccreditationCouncilonContinuingMedicalEducationtoprovidecontinuingmedicaleducationforphysicians.DesignationStatementTheAmericanRoentgenRaySocietydesignatesthiseducationalactivityforamaximumofAMAPRACategory1Credit(S)™.Physiciansshouldonlyclaimcreditcommensuratewiththeextentoftheirparticipationintheactivity.TheAmericanMedicalAssociationhasdeterminedthatphysiciansnotlicensedintheU.S.whoparticipateinthisCMEactivityareeligibleforAMAPRACategory1Credit(S)™TheAmericanRoentgenRaySocietyisastrategicpartneroftheAmericanCollegeofFacultyDisclosureStatementsThefacultymemberslistedbelowhaveindicatedthattheyhavenorelevantnancialrelation-shipsorpotentialconictsofinterestrelatedtothematerialpresented,andtheydonotdiscusstheuseofamedicaldeviceorpharmaceuticalthatisclassiedbytheFDAasinvestigationalfortheintendeduse,orthatis“off-label,”e.g.,ausenotdescribedontheproduct’slabel.RichardM.Gore,MDWilliamW.Mayo-Smith,MDAlecJ.Megibow,MD,MPHJamesA.Brink,MDMichaelP.Federle,MDIssacR.Francis,MDBrianR.Herts,MDGaryM.Israel,MDGlennKrinsky,MDJoelF.Platt,MDAndrewJ.Taylor,MDThefacultymemberslistedbelowhavedisclosedthefollowingnancialrelationshipandtherearenoconictsofinterestrelatedtotheirmaterial,andtheydonotdiscusstheuseofamedicaldeviceorpharmaceuticalthatisclassiedbytheFDAasinvestigationalfortheintendeduse,orthatis“off-label,”:e.g.,ausenotdescribedintheproduct’slabel.LincolnL.Berland,MD-Consultant,Nuance,Inc.StuartG.Silverman,MD-BookRoyalties,Lippincott,Williams,&WilkinsJudyYee,MD-ResearchGrant,GEHealthcareMarkE.Baker,MD-InformalConsultantonVolumen,Bracco;ResearchAgreement,Siemen’sMedicalSystemsW.DennisFoley,MD-MedicalAdvisoryBoardHonorarium,GEHealthcareWilliamP.Shuman,MD-ClinicalResearchGrant,GEHealthcare Berlandetal/ManagingIncidentalomasonAbdominalCT ImagingCharacterizationandWorkupIfanadrenalmasshasdiagnosticfeaturesofabenignlesionsuchasamyelolipoma(presenceofmacroscopicfat)orcyst(simplecyst-appearingwithoutenhance-ment),noadditionalworkuporfollow-upimagingisneeded.Ifthelesionis1to4cmandhasadensityofHUonCTorsignallosscomparedwiththespleenonout-of-phaseimagesofachemical-shiftMRI(CS-MRI)examination,itisalmostalwaysdiagnosticofalipid-richlipid-rich.Ifdiagnosticimagingfeaturesarenotpresentbuttheadrenalmasshasbeenstablefor1year,itislikelybenignbenign.Ifapatienthasnohistoryofcancer,therearenopriorexaminations,andthemasshasbenignimagingfeatures(lowdensity,homogeneouswithsmoothmargins),onemayconsiderafollow-upunenhancedCTorCS-MRIexaminationin12months.However,iftherearesuspi-ciousimagingfeaturesoncontrast-enhancedCT,suchasnecrosis,heterogeneousdensity,orirregularmargins,onecouldproceedwithanunenhancedCTorCS-MRIexamination.Ifthesedonotconrmthatthelesionisalipid-richadenoma,adrenalwashoutCTwith15-minutedelayedimagingtocalculatecontrastmaterialwashoutmaybehelpfulhelpful.Inpatientswithhistoriesofcancerandadrenalmasses,iftheimagingfeaturesarenotdiagnosticandthereisnopriorimagingtoconrmstability,onemayconsiderunenhancedCT,CS-MRI,orPETimagingimaging.Ifthemasscannotbediagnosedasalipid-richadenoma,adre-nalwashoutCTmaybehelpful.Inpatientswithnohistoriesofcancerandadrenalmasses4cm,onemayconsiderresection.Adenomastypicallyenhancerapidlyusingeitherio-dinatedcontrastmaterialorgadoliniumchelatesandalsodisplayrapidwashoutwashout.Althoughmetastasesgener-allyenhancerapidly,theirwashoutismoreprolonged.UsingCT,absolutepercentagewashoutvaluesarecalcu-latedusingtheformula(enhancedHUdelayedHU)/(enhancedHUunenhancedHU)100.Avalueof60%isdiagnosticofanadenoma.Relativepercentagewashoutisusedwhenanunen- If patient has clinical signs or symptoms of adrenal hyperfunction, consider biochemical evaluation Consider biochemical testing to exclude pheochromocytoma Benign imaging features = homogeneous, low density, smooth margins Suspicious imaging features = heterogeneous, necrosis, irregular margins APW = Absolute Percentage Washout RPW = Relative Percentage Washout CS-MR = Chemical Shift MRI F/U = Follow-up HU = Hounsfield Unit = decreased LEGEND Incidental Adrenal Mass 1 cm⤀Detected on CT or MR Imaging features not diagnostic 4 cm No history of cancer Benign imaging featuresPresume benign, consider 12 month F/U CT or MR Prior imaging Lesion enlarging Consider biopsy or resection Imaging features are diagnostic HU 10 or signal on CS-MR = adenoma Stable 1 year Benign Myelolipoma, ca++ = benign, no F/U No prior imagingHistory of cancer Suspicious imaging features Unenhanced CT or CS-MR HU 10 or no signal on CS-MR Adrenal washout CT APW / RPW 60/40% Adenoma 4 cm consider resection History of cancer: consider PET or biopsy Consider PET or below HU 10 or signal on CS-MR = adenoma APW / RPW 60/40% Biopsy if appropriateconsider CS-MR if not done No enhancement ( 10 HU)= cyst or hemorrhage Benign, no F/U Concerning for malignancyNo history of cancer: Fig4.FlowchartforincidentaladrenalmassdetectedonCTorMR.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 hancedCTvalueisnotavailableandtheenhancedvaluesarecomparedwith15-minutedelayedscans.Relativepercentagewashoutiscalculatedusingtheformula(en-hancedHU15-minutedelayedHU)/enhancedHU100;avalueof40%isdiagnosticforanadenomaadenoma.AdrenalwashoutCTwasusedsuccessfullytodistinguishadenomasfromnonadenomasin160of166adrenalmasseswith98%sensitivityand92%specic-specic-.RecentadvancesinimagingcharacterizationwithCT,MRI,andPEThavedecreasedtheneedforim-age-guidedpercutaneousbiopsiestocharacterizead-renalmassesmasses.However,ifanadrenalmassisen-larging,itmaybeprudenttoproceedtopercutaneousadrenalbiopsyorsurgicalresection.Inanoncologypatient,anewadrenalmassinapatientwithknownmetastaseselsewhereismostlikelyanothermetastasis.However,anisolatedadrenalmasscouldbebenignormalignant.IfthemasscannotbecharacterizedasanadenomausingCT,MRI,orPET,abiopsymaybeappropriate.Iftherearesignsorsymptomsofpheo-chromocytoma,itmaybeprudenttoobtainplasma-fractionatedmetanephrineandnormetanephrinelev-elsbeforebiopsybiopsy.Imagingexaminationsareusefultoseparateadrenaladenomasfromothermassesbutcannotbeusedtodis-tinguishhyperfunctioningadenomasfromnonhyper-functioningadenomas.Oneapproachwouldbetorelyonhistoryandphysicalexaminationtodeterminewhichpatientsshouldundergobiochemicaltestingforhyper-functioningadrenalneoplasms.Someendocrinologistsrecommendexcludinganoccult,asymptomatichyper-functioningneoplasminalladrenalincidentalomasincidentalomas.Thisapproachwouldbecostlyandisnotroutinelyperformedbymanyphysicians.Regardingtheradiologyreport,whenanadenomacanbediagnosedwithimaging,wesuggeststating,“Findingsconsistentwithabenignadenoma.Ifthereareclinicalsignsorsymptomsofadrenalhyperfunction,biochemicalevalu-ationmaybeappropriate.”NatureandScopeoftheProblemThefrequencyofdetectionofpancreaticcystsbyCTscan-ningisreportedbetween1.2%1.2%and2.6%2.6%.ForMRI,thereportedfrequencyissignicantlyhigher,at19.9%ofMRIexaminationsexaminations.Becausepancreaticcystsarequiteprevalent,apracticingradiologistmayseeseveralforevery100abdominalimagingcasesperformed.Cysticpancreatictumorsaremostoftenfranklybe-nignorlow-gradeindolentneoplasms.Inonestudythatincludedasymptomaticpatientswithpancreaticcystsinwhomtherewasoperativecorrelation,17%ofasymp-tomaticcystswereserouscystadenomas,28%weremu-cinouscysticneoplasms,27%wereintraductalpapillarymucinousneoplasms(IPMNs),2.5%wereductaladeno-carcinomas,and3.8%werepseudocystspseudocysts.Intraduc-talpapillarymucinousneoplasmswerethemostcom-moncysticneoplasmwhenbothsymptomaticandasymptomaticpatientswereevaluated.Inanotherseries,39%ofIPMNswereincidentallydetected,and50%ofIPMNsweresidebranchorbranchductIPMNswitha5-yearriskfordevelopinghigh-gradedysplasiaorinva-sivecarcinomaof15%15%.Mucinouscysticmasses,namelyIPMNsandmuci-nouscysticneoplasms,haveawell-establishedmalignantpotentiallikenedtoanadenoma-carcinomasequencesequence.Becauseofthismalignantpotential,ithasbecomeincreasinglydifcultforradiologistsevaluatingindivid-ualcasestoknowhowtoframethereporttohelpguideappropriatemanagement.Webelievethattheguida-ncebelowwillhelpintheevaluationandreportingofthemajorityoftheselesions.TheserecommendationsarealsosummarizedinFigure5DetectionandCharacterizationThisdiscussionislimitedtounexpectedpancreaticcystsinasymptomaticpatients.Asymptomaticpatientshavenoclinicalorlaboratoryindicationdirectlyreferabletothepancreas,includingbutnotlimitedtohyperamy-lasemia,recent-onsetdiabetes,severeepigastricpain,weightloss,orjaundice.Themostfrequentlydetectedcystis10mminsizesize.Cystsofthissizearepartic-ularlyprevalentonMRI.Imagingwillnotbeabletocharacterizetheselesions.Thequestionofappropriatefollow-upissubsequentlyaddressed.Thereisampleliteraturetosupportthenonsurgicalman-agementofpancreaticcysts3cmthatdonotdisplay“worrisomefeatures”features”.Somerecommend2.5cmasamaximaldiameterfornonsurgicalmanagementmanagement.Worrisomefeaturesincludelargersize,presenceofmuralnodules,dilationofthecommonbileduct,involvementofthemainpancreaticduct,andlymphadenopathylymphadenopathy.StudiesofpatientsinwhomcystshavebeenresectedoraspiratedṮ搀thatmalignancyorpremalignancydoesnotcorrelatewithcystsizealone.Thesestudiessuggestthatmucinouslesionsofanysizearepremalignantpremalignant.However,inaseriesof170of539patientswhounderwentoperativeresectionofpancreaticcysts,noinvasivecancerswerefoundinmucinouscysts3cmm.Nevertheless,establishingacystasmucinousisimpor-tantbecauseoftheirhigherriskforthepresenceorfuturedevelopmentofmalignancy.Morphologicfeaturesthataidindiagnosisofamucinoustumorinclude(1)thepresenceorabsenceofseptae(mucinouscysticneoplasmsgenerallyaremultilocular,withlargecysts),(2)theposi-tionofcalcication(mucinouscysticneoplasmstypicallyBerlandetal/ManagingIncidentalomasonAbdominalCT haveperipheralcalcication,whereasseroustumorshavecentralcalcication),(3)locationwithinthepancreas,and(4)thepresenceofmainpancreaticductinvolve-involve-.Mucinouscystictumorscanbesus-pectedwhenacystispresentinthetailofthepancreasinaperimenopausalwomanwoman.Thepresenceorabsenceofdirectcommunicationwiththemainpancreaticductmustbeestablishedtodistinguishamucinouscystictu-mor(withrelativelyhighmalignantpotential)fromabranchductIPMN(withrelativelylowmalignantpoten-tial).Three-dimensionalimagingwitheitherMRIorCTcanaddressthisquestion.Conversely,serouscystade-nomacharacteristicallydisplaysvariablydenseradialsep-taeinahoneycombedorspongiformpatternandcentralcalcication.Themoreperipheralcystsarelargerthanthemorecentralcysts.Asimplebutusefulimaging-basedclassicationsys-temdifferentiatespancreaticcysticmassesinto4mor-phologictypes:(1)unilocular(pseudocysts,mucinouscysticneoplasms,lymphoepithelialcysts,smallIPMNs,andsmallseroustumors),(2)microcystic(serouscysta-denomasandlymphoepithelialcysts),(3)macrocystic(mucinouscysticneoplasms,oligocysticseroustumors,andIPMNs)and(4)cystswithsolidcomponents(solid-appearingseroustumors,solidpseudopapillaryneo-plasms,andcysticisletcelltumors)tumors).ImplicationsofImagingandClinicalMostincidentalcystscanbedetectedonroutineabdom-inalstudies.However,ifacystneedstobecharacterized,itisrecommendedthatadiagnosisofaspeciccysttypenotbemadeunlessthepatientundergoesadedicated“pancreas-style”study.FormultidetectorCT,thiswouldrequireadual-phasecontrast-enhancedacquisitioninbothpancreaticandportalvenousphasesusinganarrowdetectorconguration.Thin-sectionimagesshouldbeavailableonaworkstationthatcanperform3-Danalysis.Magneticresonanceimagingshouldbeperformedat1.5T.Phased-arraytorsocoilsenhancesignalandparal-lelimagingincreasesspeedandimprovesresolution.Thestudyshouldincludesequencesthatdisplayin-phaseandout-of-phaseT1,T2(preferablywithfatsuppression),and3-D,fat-saturated,gradient-echoT1gadolinium-enhancedsequencesinpancreatic,portal,andequilib-riumphases.Additionally,MRcholangiopancreatogra- 1 Signs and symptoms include hyperamylasemia, recent onset diabetes, severe epigastric pain, weight loss, steatorrhea or jaundice.2 Consider decreasing interval if younger, omitting with limited life expectancy. Recommend limited T2-weighted MRI for routine follow-ups.3 Recommend pancreas-dedicated MRI with MRCP.4 If no growth after 2 years, follow yearly. If growth OR suspicious features develop, consider resection.5 BD-IPMN = branch duct intraductal papillary mucinous neoplasm. LEGEND cm Stable Growth 2-3 cm �3 cm Uncharacterized cystic mass BD-IPMN Serous cystadenoma Serous cystadenoma Uncharacterized cystic mass or other cystic neoplasm Single follow-up in 1 yr, preferably MRI Follow-up yearly Follow-up every 6 mo for 2 years Follow-up every Consider resection when 4 cm Cyst aspiration Resect, depending on co-morbidities Imaging characterization, preferably MRI/MRCP Asymptomatic Patient with Incidental Pancreatic Cystic MassDetected on CT, MRI (with or without contrast) or US Benign, no further follow-up Fig5.FlowchartforanasymptomaticpatientwithanincidentalpancreaticcysticmassdetectedonCT,MRI(withorwithoutcontrast),orultrasound(US).MRCPMRcholangiopancreatography.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 phyisnecessary.CurrentMRIscannershaverespiratorytriggered3-DsequencesforMRcholangiopancreatogra-cholangiopancreatogra-.Secretinadministrationmayfacilitatevisual-izationofthecommunicationofacystwiththemainpancreaticductduct.Byconsensus,theIncidentalFindingsCommitteesuggestsdedicatedMRIastheim-agingprocedureofchoicetocharacterizeapancreaticcyst.ThisreectsthesuperiorcontrastresolutionofMRI,facilitatingtherecognitionofseptae,nodules,andductcommunicationcommunication.Thepretestlikelihoodthatagivenlesioninanindi-vidualpatientisamalignantneoplasmisofparamountconsiderationwhendecidingonmanagement.Contro-versyexistsbetweenusingdedicatedimagingoranat-temptataspirationofacystunderendoscopicultrasoundguidance.Mostoften,thisdecisionwillbemadeonthebasisofthesizeofthecyst,locationwithinthepancreas,accessibilitytotheendoscopicultrasoundapproach,andexpertiseoftheendosonographer.Acarcinoembryonicantigenlevelintheaspirateof192ng/mLhasahighspecicityfordiscriminatingmucinousfromnonmuci-nouscysts,demonstratinghigheraccuracythancystmor-mor-.Amylaselevelsof250U/Lexcludepseudocysts.Thereisahighdegreeofoverlapbetweenthevaluesobtainedataspirationaspiration.Recentreportshavedocumentedthedevelopmentofductaladenocarci-nomainaremotesiteinthepancreasfromanIPMNIPMN.Manybelievethatthepresenceofamucinouslesionisasignalofincreasedriskforpancreaticneoplasmanywherewithinthegland.TheconsensusoftheIncidentalFindingsCommitteeisthatifsurgeryiscontemplated,aspirationofapancre-aticcyst3cmshouldbeattempted.Itisawidelyheldopinion,sharedbythiscommittee,thatcysts1.5cmneednotbeimmediatelycharacterized,whereasitisap-propriatetocharacterizeothercysts,dependingonco-morbidconditionsandlifeexpectancy.Imagingsurveillanceofpancreaticcysticneoplasmsiscontroversial.However,emergingconsensussuggeststhatselectivenonoperativemanagementinpatientswithincidentalpancreaticcystsisappropriateappropriate.Inaseriesof369of539patientswithameanradio-graphicfollow-upperiodof24months(range,1-172months),8%developedchangesthatpromptedresec-tion.Malignancieswerepresentin38%38%.Inaretro-spectivecaseseriesof79patientswithlong-termfollow-up,either5yearsbyimagingor8yearsclinically,diagnosedwithsmall⠀2cm),simplepancreaticcystsonsonographyorCTfrom1985to1996werereviewed.Ofthe22patientswithradiologicfollow-up,59%hadcyststhatremainedunchangedorbecamesmaller(meansize,8mm;meanfollow-upperiod,9years),and41%hadcyststhatenlarged,fromameanof14mmtoameanof26mm(meanfollow-upperiod,8years).Ofthe27patientswithclinicalorquestionnairefollow-up(meanfollow-upperiod,10years),nonedevelopedsymptom-aticpancreaticdisease.Twenty-threepercentdiedwithin8yearswithoutadequateradiologicfollow-up,noneofpancreas-relatedcausescauses.Anotherseriesof90pa-tientswithincidentalcystswithameanfollow-upperiodof48monthsrevealedmalignancyin1patient7yearsfromdiagnosisdiagnosis.Thefrequencyofcancerinsurgi-callyresectedcysts3cmhasbeenreportedas19%(includingsymptomaticandasymptomaticpatients)patients),butwhenonlytrulyincidentalcystsareevaluated,thefrequencyisreportedasonly3.5%3.5%.Afollow-upexaminationmustclearlyestablishthestabilityofacyst.Therefore,patientsshouldbeadvisedtoundergoserialimagingatfacilitieswithprotocolsfordedicatedpancreaticimaging.Althoughthereisnoclearconsensusamongpancreaticexpertsregardingtheopti-malimagingtestforfollow-upofpancreaticcysts,alim-itedMRIexaminationrelyingexclusivelyonT2-weightedunenhancedacquisitionshasbeenproposedasapracticalfollow-upstrategystrategy.Carefulevaluationoftheimagingndingsisdirectedatinspectingthelesionforchangesinthethicknessofthewall,muralirregularities,orfranksolidnodules.ForbranchductIPMNs,theadjacentmainpancreaticductdiametershouldberecorded.Thelesionshouldbecarefullymeasuredwithslicenumberandseriesappearinginthereport,andelec-troniccalipersshouldbeplacedontheexactimageusedtodeterminethediameters.Currently,thereisnoconsensusondeningwhatincrementofgrowthisimportant.Itiswellknownthattheprecisionofmanualmeasurementisinverselyrelatedtothelesiondiameter.Thus,itmaybedifculttodetermineifthereportedgrowthofasmalllesionistruegrowthormeasurementerror.Asofthiswriting,thereisnouniversallyacceptedfol-low-upprotocol.MostproposedprogramsarebasedontheSendaicriteriathatarosefromaconsensusconferencead-dressingthemanagementandfollow-upofmucinouspan-creaticcysts.Cysts1cmarefollowedyearly,cystsbetween1and3cmaresentforfurtherimaging(endoscopicultra-soundorMRI)lookingforseptaeandmuralnodules,andsimplecystsarefollowedat6-monthintervalsfor2yearsandthenyearly.Iftheygrowabove3cmordevelopanyworrisomefeatures,patientsareconsideredcandidatesforfor.Incontradistinction,arecommendationde-rivedfromreviewing166cystswithameansizeof2cmin150patientsrevealedthat89%showednogrowthover2years.Theonlypredictorofcystgrowthwasthepresenceofmuralnodules.Thisstudysuggestednofollow-upuntil2yearsafterdetectiondetection.IntheIncidentalFindingsCom-mittee’srecommendations,cysts2cmmaybefollowedat1-yearintervals,andifthereisnogrowth,follow-upceasesifthepatientremainsasymptomatic.Acystthatis3cmisconsideredasurgicallesionunlessitisaserouscystadenomaBerlandetal/ManagingIncidentalomasonAbdominalCT orifpatientcomorbiditiesprecludebenetfromresection.Acystbetween2and3cmmaybecharacterizedandfol-lowedsemiannuallyifmucinous,yearlyifuncharacterized,andevery2yearsifitisaserouscystadenoma.Serouscystadenomaisabenignlesion.However,studieshaveclearlydocumentedthattheselesionsmaygrow.Therefore,somerecommendresectingserouscystadenomas4cmregardlessofthepresenceofsymptomssymptoms,orinsymptomaticpatientsregardlessofsizesize.Solidpseudo-papillaryepithelialneoplasmisalow-grademalignancythatcanpresentwithcystic-appearingcomponents.Themajor-ityarefoundinyoungwomen.Theyfrequentlycontainperipheralcalcicationandvariablecontent(mostcharac-teristicallyhemorrhages)withinthecysts.Solidpseudopap-illaryepithelialneoplasmlesionsshouldundergoresection.TheIncidentalFindingsCommitteerecommendsthefollowingformanagingincidentalpancreaticcysts:1.Surgeryshouldbeconsideredforpatientswithcysts3cm.a.Ifthelesionisaserouscystadenoma,surgeryisdeferreduntilthecystis4cm.b.Solidpseudopapillaryepithelialneoplasmtumorsshouldberesected.c.Patientfactorsultimatelydeterminetheappropri-atenessofsurgicaltreatment.2.Patientswithsimple(notcontaininganysolidele-ments)cysts3cmcanbefollowed.a.Attemptsshouldbemadetocharacterizeallcysts2cmatthetimeofdetection.Magneticreso-nanceimagingistheimagingprocedureofchoice.b.Cystaspirationisstronglyadvisedbeforeanysurgeryisundertakeninapatientwithacystofthissize.c.Cysts2cmcanbefollowedlessfrequentlythanthosebetween2and3cm.d.Avoidcharacterizingcysts1.5to2cmunlessabsolutelycharacteristic.3.Thepresenceofsymptomsisacriticalfactorindecid-ingappropriatetherapy.a.Thefrequencyofmalignancyinsmallcystsissig-nicantlyhigherinsymptomaticpatients.SPECIALCONSIDERATIONSFORLOW-DOSEUNENHANCEDCTBecauseoftheadventofscreeningCTexaminationssuchasCTcolonographyandheightenedconcernaboutradi-ationexposure,low-doseunenhancedCTexaminationsoftheabdomenareincreasinginuse.Themanagementofincidentalndingsdiscoveredeitheronsuchexamina-tionsoronconventional-doseunenhancedexaminationsiscontroversial,andtherearedifferentchallenges.Low-dosetechniqueswillincreaseimagenoisebutshouldnotchangethemeanHUvaluestodetermineadrenalmassdensity.Thefollowingsectionsdescribeorgan-specicapproachesforthesetypesofexaminationsthatmayvaryfromthosedescribedabove.Themanagementofarenalmassdetectedonanunen-hancedCTscaniscontroversial.Tothebestofourknowledge,nostudieshaveaddressedhowbesttoman-agenon-fat-containingrenalmassesdetectedwithunen-hancedCT,andthus,theserecommendationsreectouropinionsonthebasisofourexperienceandunderstand-ingoftheprevalenceandnaturalhistoryofsuchndings.Furthermore,otherthanangiomyolipomas,renalmassesdetectedincidentallyonunenhancedCTscansoftencannotbeaccuratelycharacterized.OurexperiencesuggeststhatwhenarenalmassseemstobeasimplecystonanunenhancedCTscan,thechancethatthemassisbenignisextremelyhigh.However,carefuleval-uationofthemass’sfeaturesisimportant.TobeconsideredaprobablesimplecystonunenhancedCT,themassshouldbewellmarginated,containcontentsthatarehomoge-neous,andwaterattenuation(0-20HU),anddisplaynosepta,wallthickening,calcication(unlessminimal,thincalcicationwithinthewall),ornodularity.Ifanyoftheselatterfeaturesispresent,arenalmass–protocolCTorMRIwouldbeneededtodiagnosethemasswithcompletecon-dence.Sonographymaybehelpful,butinsomecasesitmaynotbedenitive.Toourknowledge,nostudiesintheliteraturehavespe-cicallyaddressedthelikelihoodofcancersinlesionsthatseemtobesimplecystsonunenhancedCT.Furthermore,whenlow-doseCTtechniquesareused,nonsimple(andpotentiallymalignant)featuresthatotherwisewouldbede-tectedwithstandard-doseCTmaynotbedetectable.Asatheoreticalexample,theheterogeneityofarenalcellcarci-nomamaybeincorrectlyattributedtonoiseoflow-doseCTandundergonofurtherevaluationorfollow-up.Also,somesimplecystsmaynotappearhomogeneous,becauseofnoise,sodifferentiatingheterogeneitysometimesencoun-teredonlow-doseCTfromaheterogeneoussolidmassmaybedifcult.Hence,althoughthepossibilityofmisinterpret-ingarenalcancerasasimplecystexists,itiswellunderstoodthatthetechnicalfactorsusedtoperformanexaminationaffectsensitivityandspecicity.TheIncidentalFindingsCommitteerecommendsthefollowingforlow-doseunenhancedCTexaminationsforrenalmasses:1.Itmaybeappropriatetointerpretincidentalrenalmassesassimplecystsunlesssuspiciousfeaturesnotedaboveareconvincinglypresent.Theargumentforadoptingthisapproachisevenstrongerwhenconsid-JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 eringsmall⠀3cm)masses,particularlythosecm.Thesmallerthemass(evenwhensolid),themorelikelyitisbenign.Furthermore,masses1cmmaynotbeabletobefullycharacterized,evenifrenalmass–protocolCTorMRIwasperformed.Althoughthisrepresentsaconsensusopinionofthecommittee,nodataareyetavailabletosupportthisapproach.2.Ifarenalmassissmall⠀3cm),homogeneous,and70HU,recentdatasuggestthatthemasscanbecondentlydiagnosedasabenignhyperattenuatingcyst(BosniakcategoryII)II).LiverTherecommendationsintheowchartinFigure3tolow-doseunenhancedproceduresaswellasstandard–radiationdoseenhancedexaminations.TheIncidentalFindingsCommitteerecommendsthefollowingforlow-doseunenhancedCTexaminationsforlivermasses:1.Inlow-riskandaverage-riskpatients,sharplymargin-ated,low-attenuation⠀20HU)solitaryormultiplemassesmaytypicallynotneedfurtherevaluation.2.Small,solitarymasses1.5cmthatarenotcysticandarediscoveredonunenhancedorstandard-doseorlow-dosescansinlow-riskandaverage-riskpatientsmaytypicallynotneedfurtherevaluation.AdrenalGlandsThelow-doseunenhancedtechniqueislesssensitivefordeterminingtheinternalarchitectureandheterogeneityofanadrenalmassthancontrast-enhancedCTwithastandardradiationexposure.Wearenotawareofanyhelpfulliteratureaddressingthetopicofadrenalmasscharacterizationonlow-doseunenhancedCTexamina-tions.Therefore,theserecommendationsrepresenttheconsensusopiniononthebasisoftheclinicalexperienceofthecommitteemembers.TheIncidentalFindingsCommitteerecommendsthefollowingforlow-doseunenhancedCTexaminationsforadrenalmasses:1.Becauseattenuationshouldnotbealteredbyalow-dosetechnique,ifthemeanattenuationofanadrenalmassis10HUonalow-doseCTexamination,onemayconcludethattheadrenalmassislikelytobeabenignadenoma.2.Ifalesionis10HUand1to4cminanasymptom-aticpatientwithoutcancer,1-yearfollow-upCTorMRImaybeconsidered,ifnopriorstudiesforcom-parisonareavailable.Priorexaminationsthatshowstabilityfor1yearcaneliminatetheneedforfurtherworkup,soeveryeffortshouldbemadetoobtainpriorCTorMRIexaminationsinthesesituations.3.Foradrenalmasses4cm,dedicatedadrenalMRIorCTshouldbeconsideredtofurthercharacterize.TherecommendationsshowninthepancreaticowchartFigure5⤀alsoapplytolow-doseunenhancedCTexamina-tions.TheimportanceofcomparisonwithpriorCTorMRIexaminationscannotbeoveremphasizedtopotentiallyavoidfurtherworkup.Specically,forlesions2cm,sta-bilityover1yearishighlysuggestiveofabenignlesionandmayeliminatetheneedforfollow-upimaging.FUTURECOMMITTEEOBJECTIVESTheIncidentalFindingsCommitteehopesthattheserecommendationswillbecomewidelyappliedandwillsearchforadditionalmethodstodisseminatethem.Thecommitteealsoexpectstoreneandadapttheserecom-mendationsandtodevelopadditionalguidanceforothertypesofincidentalndings.Toadvancethescienticevidenceregardingincidentalndings,thecommitteerecommendsthattheconcepts,terminology,andparam-etersdiscussedinthispaperbecomethebasisforfutureresearch,tohelptheresultsofsuchresearchbemoreeasilyappliedwithinacommonframework.IncidentalndingsonimagingduringdailypracticehavegrowninnumberrelatedtotherapidincreaseintheutilizationofCTandtoitsimprovedimagequality.Theseincidentalndingspotentiallyleadtoincreasedrisktothepatientandcostfromadditionalprocedures.Underscoringconcernamongphysiciansisthefearthatfailuretoreportincidentalndingsandrecommendfollow-upwillplaceradiologistsinjeopardyformalpracticelitigation,shouldalesioneventuallyleadtoalife-threateninghealthproblem.ThiseffortwithintheACR,conductedbytheInci-dentalFindingsCommittee,attemptstosystematicallydescribeavarietyofthemostcommonpotentialinciden-talndingsonabdominalCTandprovidedetailedrec-ommendationstoassistpracticingradiologistsinmakinginformeddecisionsaboutreportingsuchmassesandadvisingtheirreferringcliniciansandpatientsaboutwhetherandhowtheseshouldbemanaged.Thisispartofanongoingprojecttodevelop,rene,anddisseminateinformationaboutincidentalndingsandtocollectin-formationandsupportresearchaboutthem.ToN.ReedDunnick,MD,whosupportedandhelpedestablishtheCommitteewithintheBodyImagingCom-missionoftheACRandtoDavidKurthoftheACRstaff,Berlandetal/ManagingIncidentalomasonAbdominalCT 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2009;192:956-62.77.PaulsenSD,NghiemHV,KorobkinM,CaoiliEM,HigginsEJ.Chang-ingroleofimaging-guidedpercutaneousbiopsyofadrenalmasses:eval-uationof50adrenalbiopsies.AJRAmJRoentgenol2004;182:1033-7.78.SilvermanSG,MuellerPR,PinkneyLP,KoenkerRM,SeltzerSE.Predictivevalueofimage-guidedadrenalbiopsy:analysisofresultsof101biopsies.Radiology1993;187:715-8.79.SpinelliKS,FromwillerTE,DanielRA,etal.Cysticpancreaticneo-plasms:observeoroperate.AnnSurg2004;239:651-9.80.LaffanTA,HortonKM,KleinAP,etal.PrevalenceofunsuspectedpancreaticcystsonMDCT.AJRAmJRoentgenol2008;191:802-7.Berlandetal/ManagingIncidentalomasonAbdominalCT beenusedinthiswhitepapertoavoidtheimplicationthatthisrepresentsacomponentoftheACRPracticeGuidelinesandTechnicalStandards(whichrepresentofcialACRpolicy,hav-ingundergonearigorousdraftingandreviewprocessculminat-inginapprovalbytheACRCouncil),ortheACRAppropri-atenessCriteria(whichuseaformalconsensus-buildingapproachusingamodiedDelphitechnique).Thiswhitepa-per,whichrepresentsthecollectiveexperienceoftheIncidentalFindingsCommittee,usingalessformalprocessofrepeatedreviewsandrevisionsofthedraftdocument,doesnotrepresentofcialACRpolicy.Forthesereasons,thiswhitepapershouldnotbeusedtoestablishthelegalstandardofcareinanypartic-ularsituation.Therapidincreaseintheutilizationofcross-sectionalimagingexaminationsoverthepasttwodecades,com-binedwiththeongoingimprovementinthespatialandcontrastresolutionofthesestudies,hasledtoamarkedincreaseinthenumberofndingsdetectedthatareun-relatedtotheprimaryobjectivesoftheexaminationsexaminations.Anincidentalnding,alsoknownasaninciden-taloma,maybedenedas鍡渀incidentallydiscoveredmassorlesion,detectedbyCT,MRI,orotherimagingmodalityperformedforanunrelatedreason”reason”.Al-thoughsuchndingsareincidentaltotheprimarypur-poseofthestudy,oneanalysissuggested,“Someresearchandclinicalactivitiesaresopronetogeneratingndingsnotintentionallysoughtthatitisdisingenuoustotermthem‘unanticipated’eveniftheirprecisenaturecannotbeanticipatedinadvance”advance”.Moreimportantthanthedenitionistheactionthateachsuchndinginvokes.So,weareaskedtoconsider,“Whatistheresponsibleuseofinformationthatnobodyaskedfor?”for?”.Theburdenofextracostswithincidentalndingsoncross-sectionalimaginghasalsoraisedconcernswithinthegovernmentandthird-partypayersasmedicalimag-ingutilizationandexpenditureshaverisen.Arecentex-ampleofthiswasseenintheMay2009CMSnoncover-agedecisionregardingscreeningCTcolonographycolonography.AlthoughCTcolonographyfocusesondetectingcolo-rectalpolypstopreventcolorectalcarcinoma,anunen-hanced,low–radiationdoseCTscanofthelowerchest,entireabdomen,andpelviscontainsclinicallysignicantincidentalndingsin5%to16%ofasymptomaticpa-pa-,withahigherfrequencyinsymptom-aticpatientspatients.ThenoncoveragedecisionbyCMScitedconcernforthecostsofevaluatingextraco-lonicndingsthatarediagnosticallyindeterminate.OtherexistingordevelopingtechnologiesmayfacethistypeofeconomicscrutinyasCMSandotherthird-partypayersbecomemorefocusedoncostcontainment.Althoughcountlessstudieshavebeendevotedtode-scribingndingsrelatedtospecicmedicalconditions,relativelylittleresearchhasbeendevotedtounderstand-ingincidentalndings.Themostcommonreasontopursueincidentalndingsistodifferentiatebenignfrompotentiallyserious(includingmalignant)lesions.Al-thoughmostincidentalndingsprovetobebenign,theirdiscoveryoftenleadstoacascadeoftestingthatiscostly,provokesanxiety,exposespatientstoradiationunneces-sarily,andmayevencausemorbiditymorbidity.Articlesde-scribingcriteriafordetecting,categorizing,reporting,andmanagingsuchndingshavebeeninconsistentatbestandleavemanyunansweredquestionsquestions.PROJECTOBJECTIVESTheobjectivesofthisprojectwere:todevelopaconsensusonsetsoforgan-specicimagingfeaturesforsomecommonlyaffectedorgansystemswithintheabdomen,whichwillleadtoconsistentdeni-tionsfor,andidenticationof,incidentalndings;todevelopmedicallyappropriateapproachestomanagingincidentalndingsthatarediagnosticallyindeterminate;andtoaddressthedifferencesbetweenunenhanced,low–radiationdoseCTexaminationsandcontrast-en-hancedCTexaminationsusingstandardradiationdosesfordetectingandmanagingincidentalndings.POTENTIALBENEFICIALOUTCOMESOFTHEPROJECTBenetsanticipatedfromthiseffortincluded:reducingriskstopatientsfromadditionalunnecessaryexaminations,includingtherisksofradiationandrisksassociatedwithinterventionalprocedures;limitingthecostsofmanagingincidentalndingstopatientsandthehealthcaresystem;achievinggreaterconsistencyinrecognizing,report-ing,andmanagingincidentalndings,asacomponentofformalqualityimprovementefforts;providingguidancetoradiologistswhoareconcernedabouttheriskforlitigationformissingincidentalnd-ingsthatlaterprovetobeclinicallyimportant;andhelpingfocusresearcheffortstoleadtoanevidence-basedapproachtoincidentalndings.HISTORYOFTHEPROJECTBecauseoftheincreasingrecognitionoftheproblemsandopportunitiesofincidentalndings,considerationofaformalapproachtotheseissuesbeganwithintheACRin2006.TheIncidentalFindingsCommitteewasformedundertheauspicesoftheBodyImagingCom-missionoftheACR.Afterseveralmeetingsandconfer-encecalls,theconceptsandobjectivesdescribedaboveBerlandetal/ManagingIncidentalomasonAbdominalCT wereformulated.Theinitialintentwastodevelopguide-linesanalogoustothoseproducedbytheFleischnerSo-cietyonpulmonarynodulesnodulesandtheconsensuscon-ferencesoftheSocietyofRadiologistsinUltrasoundonthyroidnodulesnodulesandcarotidimagingimaging.BecauseofthekeeninterestamonggroupsbothwithinandoutsidetheACR,thecommittee’sparticipantswererecruitedfrommembersoftheACR,allofwhowerealsofellowsormembersoftheSocietyofComputedBodyTo-mographyandMagneticResonance,theSocietyofGastro-intestinalRadiologists,andtheSocietyofUroradiology.ContactsfromothergroupswithintheACR,includingtheColonCancerCommittee,theAppropriatenessCriteria–AdrenalPanelandtheAppropriatenessCriteria–GIPanel(LiverLesionTopic)alsohelpedensuretheconsistencyoftheguidanceproducedamongthesegroups.CONSENSUSPROCESSExpertradiologistsinrelevantorgansystemswerere-cruitedtoparticipateintheIncidentalFindingsCom-mitteeanditssubcommittees.Weplantofurtherreviewandrevisetheserecommendationsperiodically,onthebasisofcommentsandnewresearch.AlthoughthescopeofaprojecttoaddressincidentalndingsonCTislarge,thecommitteedecidedtodevelopguidanceforalimitednumberoforgansystems.Foursubcommitteeswerees-tablishedtoaddressthelargestnumberofincidentalndingswithintheabdomen,inthekidneys,liver,adre-nalglands,andpancreas.Afthsubcommitteewaschargedwithattemptingtoensuretheuseofcommonterminologyandacommonformat.Thecommitteeelectedtodeferconsideringotherincidentalndingsarisingintheabdomenandpelvis,suchasovarianmasses,spleniclesions,lymphadenopathy,andvascularabnormalities,includingarterialstenoses,abdominalaorticaneurysms,andrenalarteryaneurysms.Themem-bershipofeachsubcommitteeislistedintheAppendix.Eachsubcommitteewastaskedtodeveloporgan-specicguidance,whichwasinitiallyformulatedprimarilybythesubcommitteechairs.Whenthiswascomplete,thesesub-sectionsweredistributedtothesubcommitteemembersforfurthercommentsanddiscussion.Revisionsoftheentiredocumentwerethendistributedtothesubcommitteechairs,andmultiplerevisionsensued.Finally,thedraftwasdistributedtotheentireIncidentalFindingsCommitteeforadditionalreviewtoachieveconsensusandtoarriveatanalmanuscript.ReviewsbyotherACRcommitteeswerealsointegratedintodraftsatappropriatepointsintheprocess.Tofacilitaterapidlyformulatingandclearlycommunicat-ingthisguidance,andtoprovideconvenientgraphicsum-mariesforeasyreference,thecommitteedecidedtoexpressitsrecommendationsinowchartsandtables,buttressedwithexplanatorytext.ELEMENTSOFTHESERECOMMENDATIONSANDFLOWCHARTSCertainsubspecialtieswithinradiologyhaveaddressedin-consistenciesofdocumentationbycreatingstructuredre-porting,suchastheBreastImagingReportingandDataData.Inananalogousway,Zalisetalal,fortheWorkingGrouponVirtualColonoscopy,pro-posed“C-RADS,”whichincludesan鍅鐀classicationsys-temforextracolonicndings.Althoughthislatterclassica-tionsystemhaselementsincommonwiththeserecommendations,itisnotincludedwiththemhere.Intheowchartswithinthiswhitepaper,thealgorithmsuseyellowboxesforstepsthatinvolvedatatoaffectman-agement,suchascategorization,demographics,history,andtheresultsofstudies.Greenboxesrepresentactionsteps,suchasperformingastudy,followingup,orinterveningwithabiopsyorsurgery.Redboxesindicatethattheevalu-ationprocessshouldstop,withnofurtheractionrequired,becausethelesioncanbeconcludedtobebenign.CHALLENGESOFADDRESSINGINCIDENTALFINDINGSOneofthecrucialobstaclestomanagingincidentalnd-ingscost-effectivelyistheunwillingnessofmanyphysi-cianstoacceptuncertaintyevenwhenthechanceofaseriousdiagnosisisextremelyunlikely.Thisunwilling-nessisinpartdrivenbyapaucityofdata,thelackofclear-cutalgorithmswithregardtodiagnosticandtreat-mentstrategies,fearofpotentialmalpracticelitigation,andthedesireofpatientsandtheirfamiliestoadheretotheadage“bettersafethansorry.”Itmaybedifcultforphysiciansorpatientstoappreciateatanintellectualoremotionallevelthatanincidentalndingmightnotneedtoundergofurtherexaminationsorfollow-up.Notonlyarefurthertestslikelytoyieldabenigndiagnosis,butsuchtestingcouldevenleadtomorbiditymorbidity.Ontheotherhand,anincidentalndingcouldrepresentaser-endipitousdiscoveryofaseriousdiagnosis,suchasalargeabdominalaorticaneurysm,andbepotentiallylifesaving;hencetheconundrum.Thediscussionofcostisalsoburdenedwithstrongopinions,withsomebelievingthatcostshouldbenoobstacletoreachingacomfortablelevelofmedicalcertaintyforapositiveornegativediagnosisdiagnosis.Othersmightarguethatmedicalresourcesshouldbebestappliedwheretheyareknowntobemosteffective.However,thereisstrongscienticvalidationforapplyingmedicalstrategiesthatoptimizeresultswhileminimizingcostsandapplying“evidence-based”reason-ingtomedicaldecisionsdecisions.Unfortunately,informationaboutthecost-effective-nessofpursuingincidentalndingsislargelylacking.Therefore,achievingaconsensusofexperts,supportedbyavailableliterature,isareasonableinterimobjectiveJournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 forthisIncidentalFindingsCommittee.However,thereareseveralreasonstohypothesizethatagroupofspecialtyradiologistsfromacademicinstitutionsmightbebiasedtowardtheoveruseofimagingstudies.Forexample,thecultureofattemptingtoachievediagnosticcertaintynotedabovemaybemoreintenseinanacademicenvi-ronment,partlybecauseofthehigherintensityofillnessseenthere.Lessexperiencedphysiciansinresidencyandfellowshipmaybemoreinclinedtodependonimagingstudies,withthisinclinationsupportedbyattendingphysicianswantingtoenhancetheteachingexperience.Also,academicinstitutionsaremorelikelytohaveabroadarrayofadvancedimagingtechnologies,theuseofwhichisencouragedbythedesiretoperformresearch.Additionally,academicexpertsareintenselyfocusedintheirareasofinterestandarekeenlyawareofthemultitudeofpossi-bleseriousresultsfromincidentalndings,alsopotentiallybi-asingtheirviewpoint.Therefore,inapproachingincidentalndingsinthisway,thereisariskthatratherthantheresultsofthisprojectlimitingtheoveruseofimaging,thedetailedguid-ancegeneratedfromthisprojecteithermightnotaffectsuchoverutilizationorcouldevenincreaseit.Ourgoalwasnotnec-essarilytoreduceutilization(althoughwebelievethisisneeded)butrathertooptimizeutilization.Inthisway,onlytheappro-priateincidentalndingsareevaluatedfurther.Thesefactorswereconsideredindesigningtheserecommendations,espe-ciallyregardingtheguidanceonthelengthandfrequencyoffollow-upstudiesforindeterminatelesions.REPORTINGCONSIDERATIONSSomeconsiderationsarecommontoallorgansystems.Oneuniversalprincipleistorefertoavailablepriorrele-vantimagingexaminationswheninterpretingincidentalndings.Priorexaminationsneednotbeofpreciselythesametypeormodalitybutareusefuliftheyincludetheanatomicareainquestion,suchasachestCTscanthatincludestheupperabdomen.Also,theapproachtoinci-dentalndingsshouldbeplacedinthecontextoftheindividualpatient’ssituation.Asanextremebutcom-monexample,theneedtoreportorpursueincidentalndingsmaybeunnecessaryinpatientswithseriousmedicalcomorbiditiesorlimitedlifeexpectancy.Thewordingoftheradiologyreportisalsocontroversialandcouldfallinto4categories.ThiscanbeillustratedthroughtheexampleofarenalmassthatseemstobeasimplecystonanunenhancedCTscan.Suchalesioncould1.Describedasa“low-attenuationmassstatisticallylikelytobeasimplecyst”ora“low-attenuationmasslikelytobebenign;”2.Reportedasa“renalcyst.”Thiscontainsthespecic,implicitrecommendationtodonothingandlimitsthelengthoftheradiologyreportbutmightbeinac-curateinasmallpercentageofsituations;3.Notreportedatall.Particularlyinthecaseofsmalllesions,somewouldarguethatsuchandingissocommonandinnocuousthatitdoesnotrisetothelevelofanabnormality.Refrainingfromreportingwouldbeanalogoustoanonradiologistphysiciannotmentioninganinsignicantskinlesiononaphysicalexaminationreport.Becausemanypatientsandsomephysiciansbecomeconcernedaboutevenminornd-ings,thiswouldpreventanyriskforfurthertesting;or4.Reportedbystatingthatadenitivediagnosiscannotbemade,buttherearenofeaturestosuggestamalignantetiology,withonepossiblephrasebeing“indeterminate,nomalignantfeatures.”Thiswouldleavetheworkuptothediscretionofthereferringphysicianandperhapsthepatient.However,suchareportleavesthereferrerinaquandary.Thismayleadtounnecessarytesting,butitwouldessentiallyacknowledgethelimitsoftheexami-nationandacknowledgethattherearenoevidence-baseddatatoallowspecicrecommendations.Option1wasconsideredacceptable,butnotnecessar-ilypreferred,byallmembersoftheIncidentalFindingsCommittee.However,thecommitteecouldnotreachaconsensusonallaspectsofthissubject,becausevariousmemberspreferred,whileothersraisedobjectionstoeachofoptions2,3,and4.Somemembersnotedthatreport-ingallincidentalndingscanbevaluableifapatienthasafollow-upexaminationandonlythereportisavailable.SCANNINGTECHNIQUESInthe4organ-specicsectionsbelow(kidneys,liver,adrenalglands,andpancreas),commentsapplytostan-dard–radiationdoseexaminations,whetherperformedunenhancedorenhanced.However,low-doseunen-hancedscansmaybeperformedforCTcolonography,identifyingurinarytractcalculiandotherapplications.Webelievethatincidentalndingsidentiedonsuchlow–radiationdose,unenhancedscansrequirespecialconsiderations.Theseareseparatelyaddressedinanad-ditionalsectionfollowingthe4organ-specicsections.NatureandScopeoftheProblemTheliteratureregardingtheapproachtorenalmassesde-tectedonrenalmass–protocolCTorMRIisrepletewithcaseseries,retrospectiveanalyses,andsuggestedclinicalguidelinesthathavebeenlongacceptedandarewidelyadoptedinclinicalpracticetodaytoday.Asummaryandupdateoftheseguidelines,discussedinthecontextofanBerlandetal/ManagingIncidentalomasonAbdominalCT incidentalnding,hasbeenrecentlydetaileddetailedandthusisnotentirelyrepeatedinthiswhitepaper.DetectionandCharacterizationArenalmasscanbefoundincidentally,eitheraspartofanexaminationthatallowsthemasstobefullycharac-terizedoraspartofanexaminationthatdoesnotallowthemasstobeevaluatedfully.Manyrenalmassescanbecharacterizedcompletelyusingultrasoundorcontrastmaterial–enhancedCT;however,somerenalmassesmayrequireadditionalimagingimaging.Renalmass–protocolCTorMRIexaminations(scansobtainedbothbeforeandafterintravenouscontrastmaterial)allowmostrenalmassestobefullycharacterized.Renalmassesaredividedintocysticandsolidtypes,andrecommenda-tionsaredetailedforeachandforboththegeneralpop-ulationandpatientswithcomorbiditiesorlimitedlifeexpectancy⠀Tables1).Ingeneral,thesuggestedman-agementofrenalmassesbeginsrstwithensuringthatthemassisnottheresultofanonneoplasticconditionthatcanmimicatumor.TheseconditionsincludepseudotumorssuchascolumnsofBertin,hypertrophiedtissueadjacenttoscars,vascularanomaliesandaneu-rysms,infarcts,andinfections.Focalbacterialpyelone-phritiscommonlycausesamasslikeabnormalityinthekidney.Also,fat-containingangiomyolipomasshouldbeTable1.Managementrecommendationsforpatientswithincidentalcysticrenalmasses ImagingFeaturesComorbiditiesorLimitedLifeExpectancy䦆Hairline-thinwall;nosepta,calcications,orsolidcomponents;waterattenuation;noIgnoreIgnoreIIFewhairline-thinseptawithorwithoutperceived(notmeasurable)enhancement;Ṯ攀calcicationorshortsegmentofslightlythickenedcalcicationinthewallorsepta;homogeneouslyhigh-attenuatingmasses3cm)thataresharplymarginatedanddonotIgnoreIgnoreIIFMultiplehairline-thinseptawithorwithoutperceived(notmeasurable)enhancement,minimalsmooththickeningofwallorseptathatmayshowperceived(notmeasureable)enhancement,calcicationmaybethickandnodularbutnomeasurableenhancementpresent;noenhancingsofttissuecomponents;intrarenalnonenhancinghigh-attenuationrenalmasses⠀3cm)꜀Observe§orignoreIIIThickenedirregularorsmoothwallsorsepta,withmeasurableenhancementSurgery‡Surgery‡orobserve§IVCriteriaofcategoryIII,butalsocontainingenhancingsofttissuecomponentsadjacenttoorseparatefromthewallorseptaSurgery‡Surgery‡orobserve§ Note:Theserecommendationsaretobefollowedonlyifnonneoplasticcausesofarenalmass(eg,infections)havebeenexcluded;seetextfordetails.Therecommendationsareofferedasgeneralguidanceanddonotnecessarilyapplytoallpatients.ReprintedwithpermissionfromRadiology2008;249:16-31.Inselectedpatients(eg,young),earlysurgicalinterventionmaybeconsidered,particularlyifaminimallyinvasiveapproach(eg,laparoscopicpartialnephrectomy)canbeused.†Whenamass1cmhastheappearanceofasimplecyst,furtherworkupisnotlikelytoyieldusefulinformation.‡Surgicaloptionsincludeopenorlaparoscopicnephrectomyandpartialnephrectomy;eachprovidesatissuediagnosis.Open,laparoscopic,andpercutaneousablationmaybeconsideredwhenavailable,butbiopsywouldbeneededtoachieveatissuediagnosis.Long-term(5-yearor10-year)resultsofablationarenotyetknown.§ComputedtomographyorMRIat6and12months,thenyearlyfor5years;theintervalanddurationofobservationmaybevaried(eg,longerintervalsmaybechosenifthemassisunchanged,longerdurationmaybechosenforgreaterassurance).Cysticmasses1.5cmthatarenotclearlysimplecystsorthatcannotbecharacterizedcompletelymaynotrequirefurtherevaluationinpatientswithcomorbiditiesandinpatientswithlimitedlifeexpectancy.ReprintedwithpermissionfromRadiology2008;249:16-31. JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 excluded.Withrareexceptions,amassthatcontainsfat,particularlywhennotcalcied,canbediagnosedasanangiomyolipomawithcondence.Thesubsequentman-agementthencanbederivedandissummarizedinbles1.ThesetablesarereconguredintheformofowchartalgorithmsinFigures1Theapproachtothecysticrenalmassfollowsthetime-testedapproachofBosniakBosniak.Theta-blesandowchartsareconstructedsothatbothpatientsinthegeneralpopulationandthosewithlimitedlifeexpectancycanbemanaged.Ingeneral,sizeisnotafactorintheBosniakclassicationofcysticrenalmasses,be-causelargecysticmassesareoftenbenign,andsmallonesmaybemalignant.However,thesmallerthemass,themorelikelyitisbenign.Therefore,thecommonlyen-counteredcystic-appearingrenalmassthatistoosmalltoevaluateallofitsfeatures,includingitsCTattenuation,canbepresumedtobebenignifitdoesnotdisplayanynonsimplefeatures.Inthegreen“actionboxes”intheowcharts⠀Figures1),observationwithimaging,alsoknownasactivesurveillancesurveillance,isrecom-mendedforindeterminatemassesinBosniakcategoryIIFandisalsoanoptionformassesincategoriesIIIandIVinpatientswithlimitedlifeexpectancyorcomorbidi-tiesthatwouldincreasetheriskoftreatment.Thereisnoknownintervaloftimethatcanbeusedtodiagnoseanindeterminaterenalmasswithcertainty,al-though5yearshasbeensuggestedasareasonablelengthoftimetodiagnoseanindeterminaterenalmassasbe-nignonthebasisofthelackofmorphologicchangechange.Dependingonthelevelofsuspicion,andpatientandreferrercomfortwithobservation,boththedurationandintervalmaybealtered.AsindicatedinTables1to3andtheowcharts⠀Figures1),growthalonecannotbeusedtodenitivelydiagnoseamass(whethersolidorcystic)asmalignant.Benignmassesmaygrow,andmalignantonesmaygrowlittle,ifatallall.Regardingtheowchartforcysticrenalmasses⠀),bothBosniakcategoryIIIandIVmassesaremanagedsurgically;however,categoryIVmasseshaveagreaterprobabilityofmalignancythancategoryIIImasses,andmanagementapproachesotherthanresectioncarrymorerisk.BecausemanyBosniakcategoryIIImassesarema-lignant,surgeryisrecommendedforthegeneralpopula-tion.PercutaneousbiopsyofBosniakcategoryIIIrenalmasses,althoughcontroversial,maybehelpful,particu-larlyinpatientswithcomorbiditiesthatwouldposerisktopatientsundergoingsurgerysurgery.Ifadenitivemalignantresultcanbeobtainedwithbiopsy,surgerymaybeplannedwithcondence.Forabenignbiopsyresulttobeuseful,itshouldbebothdenitiveandspe-cicofabenignentity.Biopsyresultsthatrevealnonspe-ciccellsshouldbeviewedwithcautionandcannotbeusedalonetoguidemanagement.BecauseBosniakcate-goryIIImassestypicallycontainfewsolidelements,itmaybedifculttobothtargetandprocurediagnosticTable2.Managementrecommendationsforincidentalsolidrenalmassesinpatientsinthegeneral MassSizeProbableDiagnosisRecommendationLarge⠀3cm)Renalcellcarcinoma†Surgery‡Angiomyolipomawithminimalfat,oncocytoma,otherbenignneoplasmsmaybefoundatSmall(1-3cm)Renalcellcarcinoma†Surgery‡Ifhyperattenuating,andhomogenouslyenhancing,considerMRIandpercutaneousbiopsytodiagnoseangiomyolipomawithminimalVerysmall⠀1cm)Renalcellcarcinoma,Observeuntil1捭꜀Thin⠀3mm)sectionshelpconrmenhancement Note:Theserecommendationsarebestfollowedafternonneoplasticcausesofarenalmass(eg,infections)havebeenexcluded;seetextfordetails.Therecommendationsareofferedasgeneralguidanceanddonotnecessarilyapplytoallpatients.Benignentitiesaremorelikelyinsmallrenalmassesthanlargeones.†ProvidedthereisnodetectablefatbyCTorMRIusingprotocolsdesignedtoevaluaterenalmasses.‡Surgicaloptionsincludeopenorlaparoscopicnephrectomyandpartialnephrectomy;bothprovideatissuediagnosis.Open,laparoscopic,andpercutaneousablationmaybeconsideredwhenavailable,butbiopsywouldbeneededtoachieveatissuediagnosis.Long-term(5-yearor10-year)resultsofablationarenotyetknown.§ComputedtomographyorMRIat3to6months,12months,andthenyearly;theintervalanddurationofobservationmaybevaried(eg,shorterintervalsifthemassisenlarging).ReprintedwithpermissionfromRadiology2008;249:16-31. Berlandetal/ManagingIncidentalomasonAbdominalCT tissueforbiopsy,limitingtheabilitytoachievedeni-tivelybenignormalignantresults.However,evenifacondentdiagnosisofabenignentitycanbemadeinthesepatients,observationisstillwarranted.Wedenesolidmassesasthosethatcontainlittleornouidattenuating⠀20Hounseldunits[HU])compo-nentsandusuallyconsistpredominantlyofenhancingtissueTables2Figure2).Asdescribedforcysticrenalmasses,allsolidmassesshouldbeevaluatedrstforfeaturessuggestinganonneoplasticetiology,suchasfocalbacterialpyelonephritisorotherconditionsnotedabove.AthoroughsearchforfatcellsusingCTorMRIprotocolsdesignedtoevaluaterenalmassesshouldalsobeundertaken.Althoughtherearerareexceptions,fat-containingnoncalciedrenalmassesinadultscanbediagnosedasbenignangiomyolipo-maswithcondencecondence.Thesubsequentapproachtoasolidrenalmassisthenpredicatedmostlyonsize.Althoughthereisnosinglefeatureofarenalmassthatcanbeusedtopredictitsbiologicbehavioraccurately,sizeisareasonableandpracticalapproach.Ingeneral,large⠀3cm)solidrenalmassesarelikelymalignant;similarly,thesmallerasolidmass,themorelikelyitisbenign.Inaddition,asmallrenalcellcarcinomaismorelikelytobelowgradeandindolentbehavingthanalargeroneone.Therefore,wehavesug-gestedthatsolidmasses1cmbeobservedobserved.Thisapproachisfurthersupportedbythedifcultyofconrm-ingthatmassesofthissizeareenhancingandarethereforesolid.Partialvolumeeffectscanmimicenhancement.Thus,theuseofthin-section⠀3mm)CTandMRIisadvisedwhenbothevaluatingandobservingsuchsmallmasses.However,therearerarecasesofaggressivelybehavingsmallrenalcellcarcinomas,eventhose1cm.Therefore,obser-vationisnotcompletelywithoutriskrisk.Solidrenalmassesbetween1and3cmcanbecharacter-izedasenhancingwithcondence.Unlikemasses1cm,thesemassesarelargeenoughtobetargetedforpercutane-ousbiopsy.Althoughstillsomewhatcontroversial,insomepatients,biopsycanbeusedtoprovideadenitivediagnosisofoncocytomaandangiomyolipoma,thetwomostcom-monbenignneoplasmsfoundaftersurgicalresectionofasolidrenalmassmass.Becauseanangiomyolipomawithminimalfattypicallypresentsasahyperdense,T2-hypoin-tense,homogeneouslyenhancingmass,MRI,withorwith-outCT,canbeusedtoidentifysuchmassesandleadtopercutaneousbiopsybiopsy.Althoughoncocytomasaretypicallyhomogeneouslyenhancingmassesandmaydisplayacentralscar,thesefeaturesmayalsobefoundinoncocyticrenalcellcarcinomas.Therefore,specicrecom-Table3.Managementrecommendationsforincidentalsolidrenalmassesinpatientswithlimitedlifeexpectancyorcomorbiditiesthatincreasetheriskoftreatment MassSizeProbableDiagnosisRecommendationLarge⠀3cm)RenalcellSurgery‡orobserveAngiomyolipomawithminimalfat,oncocytoma,otherbenignneoplasmsmaybefoundatsurgery;biopsycanbeusedpreoperativelytoconrmrenalcellcarcinomaSmall(1-3cm)RenalcellSurgery‡orobserveIfhyperattenuating,andhomogenouslyenhancing,considerMRIandpercutaneousbiopsytodiagnoseangiomyolipomawithminimalVerysmall⠀1cm)Renalcellcarcinoma,Observeuntil1.5捭꜀Thin⠀3mm)sectionshelpconrmenhancement Note:Theserecommendationsarebestfollowedafternonneoplasticcausesofarenalmass(eg,infections)havebeenexcluded;seetextfordetails.Therecommendationsareofferedasgeneralguidanceanddonotnecessarilyapplytoallpatients.Benignentitiesaremorelikelyinsmallrenalmassesthanlargeones.†ProvidedthereisnodetectablefatbyCTorMRIusingprotocolsdesignedtoevaluaterenalmasses.‡Surgicaloptionsincludeopenorlaparoscopicnephrectomyandpartialnephrectomy;bothprovideatissuediagnosis.Open,laparoscopic,andpercutaneousablationmaybeconsideredwhenavailable,butbiopsywouldbeneededtoachieveatissuediagnosis.Long-term(5-yearor10-year)resultsofablationarenotyetknown.§ComputedtomographyorMRIat3to6months,12months,andthenyearly;theintervalofobservationmaybevaried(eg,shorterintervalsifthemassisenlarging);thedurationofobservationmaybeindividualized.Observationmaybeconsideredforasolidrenalmassofanysizeinapatientwithlimitedlifeexpectancyorcomorbiditiesthatincreasetheriskoftreatment,particularlywhenthemassissmall.Itmaybesafetoobserveasolidrenalmassbeyond1.5cm,butthereareinsufcientdatatoprovidedenitiverecommendationsontherisksandbenetsofobservation.ReprintedwithpermissionfromRadiology2008;249:16-31. JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 mendationsastowhichmassesshouldundergopercutane-ousbiopsycannotbemade.NatureandScopeoftheProblemRecentadvancesinmultidetectorCT,MRI,ultrasoundand2-[F]uoro-2-deoxyglucosePEThaveledtothedetectionofincidentalhepaticmassesinboththeoncol-ogyandnononcologypatientpopulationthatinthepastremainedundiscovered.Thishasengenderedamanage-mentdilemmathatisparticularlypertinenttooncologypatients,inwhomanyhepaticmass,clinicalorsubclini-cal,warrantsattention.Atautopsy,asmanyas52%ofnoncancerpatientshavebenignhepaticlesions,andlivermetastasesarefoundinasmanyas36%ofpatientsdyingwithcancercancer.Keyquestionstoanswerincludethefollowing:(1)Doesthehepaticincidentalomaputthepatientatriskforanadverseoutcome?(2)Canaprimaryormetastaticmalignancybeaccuratelyandcondentlydifferentiatedfromabenignincidentaloma?and(3)Ifabenignlesion,mightitstillrequiresurgicalintervention,suchasresectingahepaticadenomatopreventrupture?ImplicationsofImagingandClinicalStrategiesforoptimizingthemanagementofthesele-sionsareonlybeginningtoemergeintermsofdecidingwhichoftheseincidentallivermassesmaynotneedfur-therevaluation,whichmaysimplybemonitoredovertime,andwhichrequiremoreaggressiveworkup.Preop-erativepercutaneousbiopsymayminimizediagnosticerrorbutisassociatedwithapostproceduralmorbidityof2.0%to4.8%andmortalityof0.05%0.05%.TheIncidentalFindingsCommittee’sguidanceformanagingliverincidentalndingsisillustratedin.Managingincidentalliverlesionsdependsontheprobableimportanceofthemass.Thisisassessedbothbytheappearanceofthemassandthelevelofriskthateachpatienthasfordevelopingimportantlivermasses.Im-portantlivermassesarenotlimitedtomalignancies.Forexample,abenignhepaticadenomamightrequiresurgi-calintervention.Thesecategoriesaredenedasfollows: 1 These recommendations are to be followed only if non-neoplastic causes of a renal mass (e.g., infections) have been excluded; see Ref. 48 for details. The recommendations are offered as general guidance and do not necessarily apply to all patients. See Table 1 for 2 When a mass smaller than 1 cm has the appearance of a simple cyst, further work-up is not likely to yield useful information. 3 Interval and duration of observation may be varied (e.g., longer intervals may be chosen if the mass is unchanged; longer duration may be chosen for greater assurance).4 In selected patients (e.g., young), early surgical intervention may be considered, particularly if a minimally invasive approach (e.g., laparoscopic partial nephrectomy) can be utilized.5 Morphologic change refers to change in feature characteristics, such as number of septations or their thickness. Growth should be noted, but by itself does not indicate malignancy.6 Surgical options include open or laparoscopic nephrectomy and partial nephrectomy; each provides a tissue diagnosis. Open, laparoscopic, and percutaneous ablation may be considered where available, but biopsy would be needed to achieve a tissue diagnosis. Long-term (5- or 10-year) results of ablation are not yet known.7 Limited life expectancy and co-morbidities that increase the risk of treatment.8 Cystic masses 1.5 cm or smaller that are not clearly simple cysts or that cannot be characterized completely may not require further evaluation in patients with co-morbidities and in patients with limited life expectancy.9 Percutaneous biopsy of Bosniak Category III masses may be considered, but may not be diagnostic. LEGEND Incidental Cystic Renal Mass Detected on CT Bosniak IIF No morphologic change Surgery Bosniak I or II Benignno further follow-up Limited life expectancy or co-morbidities General population Limited life expectancy or co-morbidities General population Surgery Further action based on change, life expectancy and co-morbidities Bosniak III or IV If follow-up appropriate,CT or MRI at 6 and 12 mo, then yearly for 5 yrs. 3, 8 CT or MRI at 6 and 12 mo, then yearly for 5 yrs. 3, 4 If follow-up appropriate,CT or MRI at 6 and 12 mo,then yearly for 5 yrs. 3, 9 Benignno further follow-up Morphologic change Morphologic change Surgery, follow-up or no further follow-up based on life expectancy and co-morbidities Fig1.FlowchartforincidentalcysticrenalmassdetectedonCT.Berlandetal/ManagingIncidentalomasonAbdominalCT 1.Low-riskindividuals:Youngpatients(aged40years),withnomalignancies,hepaticdysfunction,hepaticmalig-nantriskfactors,orsymptomsattributabletotheliver.2.Average-riskindividuals:Patientsaged40years,withnoknownmalignancies,hepaticdysfunction,hepaticmalig-nantriskfactors,orsymptomsattributabletotheliver.3.High-riskindividuals:Patientswithknownprimarymalignancieswithapropensitytometastasizetotheliver,cirrhosis,orotherhepaticriskfactors.Hepaticriskfactorsincludehepatitis,chronicactivehepati-tis,sclerosingcholangitis,primarybiliaryhemochromatosis,hemosiderosis,hepaticdysfunc-tion,andlong-termoralcontraceptiveuse.ADRENALGLANDSNatureandScopeoftheProblemAnincidentaladrenalmass,oftenreferredtoasanadre-nalincidentaloma,isdenedasanadrenalmass⠀1cm)discoveredincidentallyonacross-sectionalimagingex-aminationperformedforanotherreason.Incidentalad-renalmassesareverycommon,estimatedtooccurinapproximately3%to7%oftheadultpopulationpopulation63].Themostfrequentpathologyforanincidentallydiscoveredadrenalmassisanonhyperfunctioningade-ade-.Itwasshowninonestudythattheover-whelmingmajorityofincidentallydiscoveredadrenalmassesarebenigninpatientswithnoknownmalignan-malignan-.Statisticsindicatethatgiventhehighpreva-lenceofnonhyperfunctioningadrenaladenomasinthegeneralpopulation,anincidentallydiscoveredadrenalmassinanoncologypatientismostlikelybenign.How-ever,theadrenalglandisalsoacommonsiteformetas-tasesand,somewhatlesscommonly,primaryadrenaltumors,includingpheochromocytomas,aldosterono-mas,andadrenalcorticalcarcinomas.Thegoalofimagingwhenanincidentaladrenalmassisdiscoveredistodifferentiateabenign“leave-alone”mass(eg,nonhyperfunctioningtumor,myelo-lipoma,hemorrhage,cyst)fromamassthatwarrantstreatment(eg,metastasis,pheochromocytoma,adre-nalcorticalcarcinoma).Fromanimagingperspective,anoptimalalgorithmshouldbeusedtodiagnosebothleave-alonemassesandmassesthatneedtreatment,usingasfewtestsaspossible.TheadrenalowchartFigure4⤀andrecommendationsdescribedhereat- 1 These recommendations are to be followed only if non-neoplastic causes of a renal mass (e.g., infections and fat-containing angiomyolipomas) have been excluded; see Ref. 48 for details. The recommendations are offered as general guidance and do not necessarily apply to all patients.2 Differential diagnosis includes renal cell carcinoma, oncocytoma, angiomyolipoma. Benign entities are more likely in small renal masses than large ones.3 Limited life expectancy and co-morbidities that increase the risk of treatment.4 Interval and duration of observation may be varied (e.g., shorter interval if the mass is enlarging).5 Probable diagnosis renal cell carcinoma, provided there is no detectable fat at CT or MRI using protocols designed to evaluate renal masses. 6 If hyperattenuating and homogeneously enhancing, consider MRI and percutaneous biopsy to diagnose angiomyolipoma with minimal fat.7 Surgical options include open or laparoscopic nephrectomy and partial nephrectomy; both provide a tissue diagnosis. Open, laparoscopic, and percutaneous ablation may be considered where available, but biopsy would be needed to achieve a tissue diagnosis. Long-term (5- or 10-year) results of ablation are not yet known.8 Observation may be considered for a solid renal mass of any size in a patient with limited life expectancy or co-morbidities that increase the risk of treatment, particularly when the mass is small. It may be safe to observe a solid renal mass beyond 1.5 cm; however, there are insufficient data to provide definitive recommendations on the risks and benefits of observation. Thin ⠀9 Probable diagnosis renal cell carcinoma. Angiomyolipoma with minimal fat, oncocytoma, and other benign neoplasms may be found at surgery.10 Percutaneous biopsy can be utilized preoperatively to confirm renal cell carcinoma. LEGEND Incidental Solid Renal Mass Detected on CT 1-3 cm Surgery Surgery 7, 10 Follow-up m Limited life expectancy or co-morbidities General population General population Surgery Follow-up General population �3 cm Follow-up until 1 cm:CT or MRI at 3-6 mo and 12 mo, then yearly Follow-up until 1.5 cm:CT or MRI at 3-6 mo and 12 mo, then yearly Hyperattenuating, homogeneously enhancing: consider MRI, biopsy Limited life expectancy and co-morbidities Limited life expectancy and co-morbidities Fig2.FlowchartforincidentalsolidrenalmassdetectedonCT.JournaloftheAmericanCollegeofRadiology/Vol.7No.10October2010 tempttodoboth.Thealgorithmreectsthemostcommonlyencounteredimagingscenarios.However,itisimportanttonotethatthereareexceptionstosomeoftherecommendationsdependingonindivid-ualpatients’presentationsandhistories.Asnotedinothersectionsofthiswhitepaper,ifapatienthaslimitedlifeexpectancyorseverecomorbidities,workupofanincidentallydiscoveredadrenalmassmaynotbeappropriate.Readersarealsodirectedtoarecentcomprehensivereviewonthistopic Incidental Liver MassDetected on CT 0.5-1.5 cm �1.5 cm Follow-up Follow-up .5 cm Low attenuation, benign imaging features Low attenuation, suspicious imaging features Flash filling (robustly enhancing) Low attenuation, benign imaging features Benign diagnostic imaging features 8, 9 No benign diagnostic imaging features Low attenuation, suspicious imaging features Flash filling (robustly enhancing⤀ Low or average risk 1, 2 Any risk level 1, 2, 3 Any risk level 1, 2, 3 Low or average risk 1, 2 High risk Low risk Follow-up Evaluate Biopsy, core preferred Follow-upevaluate or biopsy, core preferred Average risk High risk 3 Benign, no further follow-up Benign, no further follow-up Benign, no further follow-up Benign, evaluate if FNH, adenoma8, 9 Evaluate Follow-up Benign, no further follow-up 8, 9 High risk 3 AB 1 Low risk individuals: Young patient (40 years old), with no known malignancy, hepatic dysfunction, hepatic malignant risk factors, or symptoms attributable to the liver.2 Average risk individuals:� Patient 40 years old, with no known malignancy, hepatic dysfunction, abnormal liver function tests or hepatic attributable to the liver.3 High risk individuals: Known primary malignancy with a propensity to metastasize to the liver, cirrhosis, and/or other hepatic risk factors. Hepatic risk factors include hepatitis, chronic active hepatitis, sclerosing cholangitis, primary biliary cirrhosis, hemochromatosis, hemosiderosis, oral contraceptive use, anabolic steroid use.4 Follow-up CT or MRI in 6 months. May need more frequent follow-up in some situations, such as a cirrhotic patient who is a liver transplant candidate.5 Benign imaging features: Typical hemangioma (see below), sharply marginated, homogeneous low attenuation (up to about 20 HU), no enhancement. May have sharp, but irregular 6 Benign low attenuation masses: Cyst, hemangioma, hamartoma, Von Meyenberg complex (bile duct hamartomas).7 Suspicious imaging features: Ill-defined margins, enhancement (more than about 20 HU), heterogeneous, enlargement. To evaluate, prefer multiphasic MRI.8 Hemangioma features: Nodular discontinuous peripheral enhancement with progressive enlargement of enhancing foci on subsequent phases. Nodule isodense with vessels, not parenchyma.9 Small robustly enhancing lesion in average risk, young patient: hemangioma, focal nodular hyperplasia (FNH), transient hepatic attenuation difference (THAD) flow artifact, and in average risk, older patient: hemangioma, THAD flow artifact. Other possible diagnoses: adenoma, arterio-venous malformation (AVM), nodular regenerative hyperplasia. Differentiation of FNH from adenoma important especially if larger than 4 cm and subcapsular.10 Hepatocellular or common metastatic enhancing malignancy: islet cell, neuroendocrine, carcinoid, renal cell carcinoma, melanoma, choriocarcinoma, sarcoma, breast, some pancreatic lesions. LEGEND Incidental Liver MassDetected on CT Fig3.FlowchartforincidentallivermassdetectedonCT.Berlandetal/ManagingIncidentalomasonAbdominalCT 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ManagingIncidentalFindingsonAbdominalCT:WhitePaperoftheACRIncidentalFindingsCommitteeLincolnL.Berland,MD,StuartG.Silverman,MD,RichardM.Gore,MDWilliamW.Mayo-Smith,MD,AlecJ.Megibow,MD,MPH,JudyYee,MDJamesA.Brink,MD,MarkE.Baker,MD,MichaelP.Federle,MDW.DennisFoley,MD,IsaacR.Francis,MD,BrianR.Herts,MDGaryM.Israel,MD,GlennKrinsky,MD,JoelF.Platt,MDWilliamP.Shuman,MD,AndrewJ.Taylor,MDAsmultidetectorCThascometoplayamorecentralroleinmedicalcareandasCTimagequalityhasimproved,therehasbeenanincreaseinthefrequencyofdetecting“incidentalndings,”denedasndingsthatareunrelatedtotheclinicalindicationfortheimagingexaminationperformed.These“incidentalomas,”astheyarealsocalled,oftenconfoundphysiciansandpatientswithhowtomanagethem.Althoughitisknownthatmostincidentalndingsarelikelybenignandoftenhavelittleornoclinicalsignicance,theinclinationtoevaluatethemisoftendrivenbyphysicianandpatientunwillingnesstoacceptuncertainty,evengiventherarepossibilityofanimportantdiagnosis.Theevaluationandsurveil-lanceofincidentalndingshavealsobeencitedasamongthecausesfortheincreasedutilizationofcross-sectionalimaging.Indeed,incidentalndingsmaybeserious,andhence,whenandhowtoevaluatethemareunclear.Theworkupofincidentalomashasvariedwidelybyphysicianandregion,andsomestandardizationisdesirableinlightofthecurrentneedtolimitcostsandreducerisktopatients.Subjectingapatientwithanincidentalomatounnecessarytestingandtreatmentcanresultinapotentiallyinjuriousandexpensivecascadeoftestsandprocedures.Withtheparticipationofotherradiologicorganizationslistedherein,theACRformedtheIncidentalFindingsCommitteetoderiveapracticalandmedicallyappropriateapproachtomanagingincidentalndingsonCTscansoftheabdomenandpelvis.Thecommitteehasusedaconsensusmethodbasedonrepeatedreviewsandrevisionsofthisdocumentandacollectivereviewandinterpretationofrelevantliterature.Thiswhitepaperprovidesguidancedevelopedbythiscommitteeforaddressingincidentalndingsinthekidneys,liver,adrenalglands,andpancreas.KeyWords:Incidentalndings,incidentaloma,pancreaticcyst,renalcyst,liverlesion,adrenalnoduleJAmCollRadiol2010;7:754-773.Copyright꤀2010AmericanCollegeofRadiologyThiswhitepaperismeantnottocomprehensivelyreviewtheinterpretationandmanagementofsolidmassesineachorgansystembuttoprovidegeneralguidanceformanagingincidentallydiscoveredmasses,appreciatingthatindividualwillvarydependingoneachpatient’sspeciccircum-stances;theclinicalenvironment,availableresources;andthejudgmentofthepractitioner.Also,thetermhasnot DepartmentofRadiology,UniversityofAlabamaatBirmingham,Birming-ham,Alabama.DepartmentofRadiology,BrighamandWomen’sHospital,Boston,Massa-DepartmentofRadiology,EvanstonHospital,Evanston,Illinois.DepartmentofRadiology,BrownUniversitySchoolofMedicine,Provi-dence,RhodeIsland.DepartmentofRadiology,NYU-LangoneMedicalCenter,NewYork,NewYork.DepartmentofRadiology,UniversityofCalifornia,SanFrancisco,SanFran-cisco,California.DepartmentofDiagnosticRadiology,YaleUniversitySchoolofMedicine,NewHaven,Connecticut.DepartmentofRadiology,ClevelandClinic,Cleveland,Ohio. DepartmentofRadiology,StanfordUniversityMedicalCenter,Stanford,DepartmentofRadiology,MedicalCollegeofWisconsin,Milwaukee,Wisconsin.DepartmentofRadiology,UniversityofMichigan,AnnArbor,Michigan.RadiologyAssociatesofRidgewood,PA,Waldwick,NewJersey.DepartmentofRadiology,UniversityofWashingtonSchoolofMedicine,Seattle,Washington.DepartmentofRadiology,VirginiaCommonwealthUniversityMedicalCenter,Richmond,Virginia.Correspondingauthorandreprints:LincolnL.Berland,MD,UniversityofAlabamaatBirmingham,DepartmentofRadiology,619S19thStreet,N348,Birmingham,AL35249-1900;e-mail: ꤀2010AmericanCollegeofRadiologyDOI10.1016/j.jacr.2010.06.013