Mammography - National Institute of Biomedical Imaging and ...

Mammography is an x-ray imaging method used to examine the breast for the early detection of cancer and other breast diseases. It is used as both a diagnostic ... Skiptomaincontent scienceeducation ScienceTopics Mammography Mammography Share:   ScienceEducation Whatismammography? Howdoesitwork? Whatwilltheresultslooklike? Whydoesthebreastneedtobecompressed? Whatisdigitalmammography? Whatistomosynthesis(3Dmammography)? Whatarethelimitsofmammography? Arethererisks? WhenshouldIgetamammogram? WhatareexamplesofNIBIB-fundedprojectsinbreastcancerscreening? Whatismammography? Mammography isanx-rayimagingmethodusedtoexaminethebreastfortheearlydetectionofcancerandotherbreastdiseases.Itisusedasbothadiagnosticandscreeningtool. Howdoesitwork? Source:GettyImagesDuringamammogram,apatient’sbreastisplacedonaflatsupportplateandcompressedwithaparallelplatecalledapaddle.Anx-raymachineproducesasmallburstof x-rays thatpassthroughthebreasttoadetectorlocatedontheoppositeside.Thedetectorcanbeeitheraphotographicfilmplate,whichcapturesthex-rayimageonfilm,orasolid-statedetector,whichtransmitselectronicsignalstoacomputertoformadigitalimage.Theimagesproducedarecalledmammograms. Onafilmmammogram,lowdensitytissues,suchasfat,appeartranslucent(i.e.darkershadesofgrayapproachingtheblackbackground).,whereasareasofdensetissue,suchasconnectiveandglandulartissueortumors,appearwhiteronagraybackground.Inastandardmammogram,bothatopandasideviewaretakenofeachbreast,althoughextraviewsmaybetakenifthephysicianisconcernedaboutasuspiciousareaofthebreast. Whatwilltheresultslooklike? AmammogramshowingasmallcancerouslesionAradiologistwillcarefullyexamineamammogramtosearchforhighdensityregionsorareasofunusualconfigurationthatlookdifferentfromnormaltissue.Theseareascouldrepresentmanydifferenttypesofabnormalities,includingcanceroustumors,non-cancerousmassescalledbenigntumors,fibroadenomas,orcomplexcysts.Radiologistslookatthesize,shape,andcontrastofanabnormalregion,aswellastheappearanceoftheedgesormarginsofsuchanarea,allofwhichcanindicatethepossibilityofmalignancy(i.e.cancer).Theyalsolookfortinybitsofcalcium,calledmicrocalcifications,whichshowupasverybrightspecksonamammogram.Whileusuallybenign,sitesofmicrocalcificationsmayoccasionallysignalthepresenceofaspecifictypeofcancer.Ifamammogramshowsoneormoresuspiciousregionsthatarenotdefinitiveforcancer,theradiologistmayorderadditionalmammogramviews,withorwithoutadditionalmagnificationorcompression,ortheymayorderabiopsy.Anotheralternativemaybereferralforanothertypeofnon-invasiveimagingstudy. Whydoesthebreastneedtobecompressed? Compressionholdsthebreastinplacetominimizeblurringofthex-rayimagethatcanbecausedbypatientmotion.Also,compressionevensouttheshapeofthebreastsothatthe x-rays cantravelthroughashorterpathtoreachthedetector.Thisreducesthe radiation doseandimprovesthequalityofthex-rayimage.Finally,compressionallowsallthetissuestobevisualizedinasingleplanesothatsmallabnormalitiesarelesslikelytobeobscuredbyoverlyingbreasttissue. Whatisdigitalmammography? Adigitalmammogramusesthesamex-raytechnologyasconventionalmammograms,butinsteadofusingfilm,solid-statedetectorsareusedtorecordthex-raypatternpassingthroughthebreast.Thesedetectorsconvertthe x-rays thatpassthroughthemintoelectronicsignalsthataresenttoacomputer.Thecomputerthenconvertstheseelectronicsignalsintoimagesthatcanbedisplayedonamonitorandalsostoredforlateruse.Severaladvantagesofusingdigitalmammography overfilm mammography include:theabilitytomanipulatetheimagecontrastforbetterclarity,theabilitytousecomputer-aideddetectionofabnormalities,andtheabilitytoeasilytransmitdigitalfilestootherexpertsforasecondopinion.Inaddition,digitalmammogramsmaydecreasetheneedforthere-takes,whicharecommonwithfilm mammography duetoincorrectexposuretechniquesorproblemswithfilmdevelopment.Asaresult,digital mammography canleadtolowerx-rayexposures. Todate,thereisnoevidencethatdigitalmammographyisbetterthatfilmmammographyforreducingawoman’sriskofdyingfrombreastcancer,however,digitalscreeningmaybemoreaccurateforfindingcancersinyoungerwomenorwomenwithdensebreasts.ReadmoreontheNationalCancerInstitute’swebpageonmammograms. Whatistomosynthesis(3Dmammography)? DigitalBreastTomosynthesis,alsoknownas3Dmammography,isanFDA-approvedmethodforbreastcancerscreeninginwhich x-rays ofthebreastaretakenatdifferentanglestogeneratethincross-sections. The3Drepresentationofthebreastissimilartothe3dimagescreatedbystandardCTtechnology.TomosynthesisdiffersfromCTtechnologyinthatsignificantlyfewerx-raybeamsareprojectedthroughthebreastthanwithCTandthex-rayexposuretotherestofthechestisdramaticallyreduced.Hence,the radiation dosedeliveredtothebreastbytomosynthesisissimilartothatdelivered2Dmammography.Whiletomosynthesisusesverylow-dose x-rays,itiscurrentlymostoftenusedinadditionto2Dmammography,makingthetotal radiation dosehigherthanstandardmammography.Earlyevaluationsof3Dmammographysuggestanimproveddetectionofbreastcancersthanseenwith2Dmammography,butextensivelarge-scalecomparisonsoftomosynthesiswith2Dmammographyinrandomizedstudiesarestillinprocess.Therefore,researchersdonotknowwithfullcertaintywhether3Dmammographyisbetterorworsethanstandardmammographyatavoiding false-positiveresults andidentifyingearlycancersinalltypesofpatients. Whatarethelimitsofmammography? Forcertaintypesofbreasts,mammogramscanbedifficulttointerpret. Thisisbecausethereisawidevariationinbreasttissuedensityamongwomen.Denserbreastsaremoredifficulttoimage,andmoredifficulttoassessfortumordiagnosis. Forthisandotherreasons,thesensitivityof mammography indetectingcancercanvaryoverawiderange. Formanydifficultcases,x-ray mammography alonemaynotbesufficientlysensitiveoraccurateindetectingcancer,soadditionalimagingtechnologies,suchas ultrasoundormagneticresonanceimaging(MRI) mayalsobeusedtoincreasethesensitivityoftheexam. Recently,studieshaveshownthatatypeofnuclearmedicinecalledmolecularbreastimaging(MBI)maybeaneffectiveandlessexpensivealternativetoMRIforclarifyingtestresultsinpatientswithdensebreasts.DuringMBI,patientsaregivenaninjectionofradioactivemoleculesthatareselectivelytakenupbycancercells.Specialcamerasthatdetectradioactivityarethenusedtorevealthesecancercellsinthebreasttissue. Arethererisks? Because mammography uses x-rays toproduceimagesofthebreast,patientsareexposedtoasmallamountofionizing radiation.Formostwomen,thebenefitsofregularmammogramsoutweightherisksposedbythisamountofradiation.Theriskassociatedwiththisdoseappearstobegreateramongyoungerwomen(underage40).However,insomecases,thebenefitsofusing mammography todetectbreastcancerunderage40mayoutweightherisksof radiation exposure.Forexample,amammogrammayrevealthatasuspiciousmassisbenignand,therefore,doesn’tneedtobetreated. Additionally,ifatumorismalignantandiscaughtearlybymammogram,asurgeonmaybeabletoremoveitbeforeitspreadsandrequiresmoreaggressivetreatmentsuchaschemotherapy. WhenshouldIgetamammogram? Severalorganizationsandprofessionalsocietieshavedevelopedguidelinesformammographyscreening.Youcanreadmoreabouttheserecommendationsontheirwebsitesbelow.Allrecommendthatwomentalkwiththeirdoctoraboutthebenefitsandpotentialharmsofmammography,whentostartscreening,andhowoftentobescreened.UnitedStatesPreventiveServicesTaskForceTheAmericanCancerSocietyAmericanCollegeofRadiology WhatareexamplesofNIBIB-fundedprojectsinbreastcancerscreening? BreastimagegeneratedwithdedicatedbreastPET/CT.Orangeandpurplerepresentareasofincreasedmetabolicactivitywhichindicatethepresenceofatumor.Source:JohnBoone,Ph.D.,UCDavisDedicatedBreastCT:ResearchfundedbyNIBIBhasledtothedevelopmentofabreastCTscanner(bCT)thatallowsradiologiststoviewthebreastinthreedimensionsandhasthepotentialtorevealsmalltumorsobscuredbehinddensebreasttissue.Thescannerusesa radiation dosecomparableto mammography bysending X-rays onlythroughthebreastandnotthechest. Atpresent,morethan600womenhavebeenimagedusingbCTinclinicaltrials. ResultsfromthesetrialssuggestthatbCTissignificantlybetteratdetectingtumorsthanmammography,though mammography isbetteratdetectingmicrocalcifications. Recently, positronemissiontomography(PET) technologyhasbeenincorporatedintothebCTplatform. APETscanhighlightsareasofincreasedmetabolicactivity,whichcouldindicatethepresenceofatumor. Additionally,injectionofa contrastagent hasbeenshowntoimprovebCT’sabilitytodetectmicrocalcificationsandcouldhelpradiologistsdistinguishbenignfrommalignanttumors. ResearchiscurrentlyfocusedonwaysinwhichbCTcouldbeusedtoprovidereal-timeimageguidanceforbiopsyneedleplacementandminimallyinvasiveablationoftumors.  Near-Infrared,DiffuseLightImagingwithUltrasonicGuidance:ResearchersfundedbyNIBIBhavedevelopedanovel,hand-heldbreastimagingsystemthatusesvisiblelighttodistinguishbenignlesionsfromearly-stagecancer.Thesystemcreatesmapsoftissuedensityinalocalareaofthebreastbasedonhowthetissuescatterslight;thedenserthetissue,themorelightisscattered,andthegreaterthelikelihoodthatthetissueiscancerous.Themethodiscurrentlybeingtestedinalargenumberofpatientsundergoingsurgerytoremoveabreasttumor.Earlyresultsindicatethattheimagingsystemmaybeapromisingadjuncttomammographyfordiagnosingbreastcanceranddeterminingdiseaseprognosis.Inaddition,thesystemcouldallowsurgeonstomorerapidlydeterminetumormarginsduringsurgerycomparedtomethodsusedoverthepasttwentyyears.Thiscouldpotentiallyreducesurgeriesthatneedtoberepeatedbecausenotallcanceroustissuewasremovedinitially. Thumbnail MammogramSciEd.jpg ViewandDownloadScienceTopicFactSheets(PDFs) ExploreMore ThereissomuchmoretoexploreatNIBIB. HealthTopicsBreastCancerWomen'sHealth ResearchTopicsComputedTomography(CT)MammographyX-ray ProgramAreasX-ray,Electron,andIonBeam