医学影像学课件：肺脏结构图片及X线表

Normalcardiothoracicimaginglandmarks,PAview

COMMENTS

Keycardiothoraciclandmarksincludethesuprasternalnotchjustabovethejunctionoftheclaviclesandsubxiphoidregion.Thebonysternumoverliesthespineonthefrontalfilmandisthereforenotclearlyidentifiedinthatprojection.Thejunctionoftheribswiththesternumisusuallycomposedofcalcifiedcartilageandareshownasasegmentalchangeastheribapproachesthesternum.Notethesmallspacesbetweentheribsatthesternumwhichistheonlyallowablesofttissuewindowforultrasoundimagingoftheheart.Thenipplesaresofttissueandsometimesappearonchestx-raysassuspicioussymmetricnodulesinthelowerlungfields.Normalcardiothoracicimaginglandmarks,lateralview

LaterallandmarksonchestradiographsAlthoughitisnotuncommontofindthelateralchestfilmdisplayedwiththebodyeitherlookingleftorright,dependingonwhichsideofthepatientwasclosesttothefilm,itismostsensibletopresentthelateralthefilmalwaysinsomefixedmannertotheviewersothatconsistentvisualpatternrecognitioncanbeachieved.Afavoreddirectionisasifthepatientwerebeingviewedthroughtheleftlateralchestwall,sothattheimageappearsasifthepatientisfacingtheviewer'sleft.Thisfilmorientationprovidesanassessmentoftheoverallheartsizewhichshouldshowaspaceanteriorlybelowthesternumiftherightcardiacchambersarenotenlarged.Thedomeofthediaphragmwillappearconvexupward.Thedomethatcanbeseentoextendmostanteriorlyisidentifiedastherightdiaphragm.Theleftdiaphragmaticdomemergeswithundersurfaceoftheheart,atissueofthesamedensity,andthereforetendstodisappearanteriorly.Anothermarkeroftheleftdiaphragmisthegastricairbubblewhichshouldmostcloselyapproachtheboundaryoftheleftdiaphragmifthepatienthasnormalcardiacsitus.Thetracheashouldbereadilyvisibletothecarina.Wherethereareslightamountsoffluidinthefissuresorwherethefissureisprojectedalongitsedge,therightmiddlelobeandtherightlowerlobeinter-pulmonaryfissuresarecommonlyvisible.Thethoracicvertebraetendtobedifficulttovisualizeattheupperlevelsbecauseoftheoverlappingshouldersandsofttissuesoftheupperthorax,butappearasquitetransparentinthelowerthoracicspinejustabovethediaphragm.Grossanatomyofthethoraxandmediastinum

CardiothoracicanatomyNotetheextensiveoverlapofsofttissuestructuresresultsinaconfusingcomplexity,particularlythepulmonaryvasculature.Notethepulmonaryarteryisdefinedinbluebecauseitcontainsdeoxygenatedbloodandthepulmonaryvenousstructuresareredsincethebloodhasbeenperfusedandoxygenatedinthealveoli.Notethetwofissuresseparatingthethreelobesoftherightlung(rightupper,rightmiddle,andrightlowerlobe)andthesinglefissureontheleftseparatingthelingulafromtheleftlowerlobe.Anteriorradiographicviewofcardiacanatomy

Radiographicviewoftheheart

Detailedillustrationandradiographofthecentralmediastinumanatomy.Theillustrationdemonstratesthecomplexityoftheoverlappingvascularstructuresandemphasizesthedifficultywithwhichseparatingoutindividualvesselsoccurontheradiograph.Intheillustration,thepulmonaryarteryisshowninbluebecauseitcontainsdeoxygenatedbloodandthepulmonaryveinsandaorticarchareredsincetheyareoxygenated.Intheradiograph,notetheaorticknobwhicharchesoverthemainpulmonaryarteryandthefaint,lesser-denseareasrepresentingtheair-containingtubesofthetrachea,carina,andmainbronchi.Thespinousprocessesandvertebraearefaintlyvisiblethroughthecentraldensityoftheheartandthesharpverticallinedescendingfromtheaorticknobafterthetake-offoftheleftsubclavianrepresentsthedescendingaorta.Graphicsuperimpositionoftheheartandgreatvesselsshowsthepositionofthesignificantsegmentsandboundariesofthevariouschambers.Withinthecardiacsilhouettemostnon-calcifiedsofttissuestructuressuchasthevalvesarenotapparentsincetheymergewiththesimilarradiographicdensityofthebloodpool.Onlywherethereiscalcification(suchasthemitralannulusoraorticvalve)willastructurebespecificallyidentifiedwithinthecardiacsilhouette.Thepulmonaryarteriestendtobemoreverticallyorientedwhereasthepulmonaryvenousstructuresaremorehorizontalastheydrainintotheleftatrium.Notethelateralwidthoftheheartfromtherightatrialbordertotheleftventricularapexisgenerallylessthanonehalfthewidthofthewholethorax.AnatomyofthetracheaandbronchiCOMMENTS

Schematicdiagramofthemajorpulmonarysegmentsandthebronchialsupply.Notethattherightlungisdividedintothreemajorsegments:rightupperlobe(pink),rightmiddlelobe(yellow),andrightlowerlobe(blue).Thelobesareseparatedbyfissuresthatslopeupwardposteriorlyandareseenasatransparentslopingplane.Theleftlungisdividedintoonlytwolobes:thelingula(pink)andtheleftlowerlobe(blue).Structureofthebronchiolesandalveoli

BronchiolesandalveoliThisillustrationshowstheclusteredconfigurationoftheterminalbronchiolesastheyconnecttotheterminalalveolarsacs.Thesemi-sphericalsacsconnectbetweeneachotherviaporesofKohn.Thealveolarairspaceallowsintimatecontactbetweentheunoxygenatedblooddeliveredbythepulmonaryarterypassingthroughtheenrichedcapillarynetworktoexchangeoxygen,exchangingcarbondioxideintotheairspaceandthehemoglobinabsorbingoxygenacrossthemembrane.Thisresultsinnearly100%oxygen-saturatedbloodinthepulmonaryvein.Theterminalbronchiolesarenotedtobewrappedbysomeelasticfibersaswellassmoothmusclebandswhicharecapableofreactingtosympatheticneuralcontrol.Detailedillustrationenlargingthesectionofthealveolarsacsshowingtheopeningsofthealveolarductsintothesemi-sphericalprotrusionswhichallowsintimatecontactofunoxygenatedblooddeliveredbythepulmonaryarterieswithcapillarysurfaceareastoallowgasexchange.Theairventilatingthesacscontainsupto20%oxygen.Aftergaseousexchangewithpulmonaryarterialbloodthesaturatedpulmonaryvenousbloodcanbe100%saturatedwithanoxygentensionof100mmofHg.Carbondioxidetraversesthemembraneinreverse(bloodstreamtoairsac)andresultsina5%partialpressureofcarbondioxideintheexpiredgas.Imagefinding:NormalchestPAfilm

Imagefinding:NormalchestPAfilm,case2

Erectposterior-anterior("PA")chestradiographPAimagescommonlyshowsignificantdifferencesfromAP(antero-posterior)filmsparticularlyinrelationtotheproportionalsizeofthemediastinum.ThePApositionplacestheheartanduppermediastinumclosertothefilmwithgreaterdistancetotheexposingXraytube(generally72inches)makingtheXraysmoreparallelastheyenterthebodyandavoidingdisproportionalenlargementofanteriorvs.posteriorstructures.Theeffectsofgravityhavevisibleeffectsonthepulmonaryvasculaturesincethepulmonaryarterypressuresarelow(~25mmHg.insystoleand~12mmHg.indiastole)andthevesselwallsaresoftandcompliant.Theupperlungarterialvesselsinuprightposture,beingwellabovecardiacchamberlevel,areusuallymuchlessprominentthanthelowerlobevesselswhichareatorbelowcardiacchamberlevel.Anindicationofelevatedpulmonaryarterypressureduringcardiaccongestivefailureisavisibleshiftofbloodwithafillingoutoftheupperlobevesselsontheuprightfrontalfilmwhichindicatesageneralizedincreaseinthecentralpulmonaryarterypressure.Imagefinding:Normalsupinechestfilm

Anterior-posteriorsupineradiograph

OnasupinefrontalXrayofthechesttherearesignificantdifferencesintheappearanceofnormalpulmonaryvasculatureandmediastinum.ThecloserdistanceoftheexposingXraytube(oftenonly40inchesfromthefilmcassette)makestheXraysmorediverginganddisproportionallyenlargestheappearanceofstructuresthatarefartherfromthefilm(theanteriorbodystructuressuchastheascendingaorta).

Althoughthepulmonaryarterypressuresarelow(~25mmHg.insystoleand~12mmHg.indiastole)andthevesselwallsaresoftandcompliant,theupperlungarterialvesselsandthelowerlobevesselsarenowatthesamelevelasthecardiacchambers.Thusthesupinefilmcanbeexpectedtoshowupperpulmonaryarteryvesselsasequallyprominenttothoseinthelowerlung,afindingthatdifferssignificantlyfromuprightposturebutshouldnotbeconfusedwithcongestivefailure.

Pulmonaryangiogram,arterial

Arterialangiogram

Angiogramsarecreatedbyinjectinganiodinesolutionintothebloodstream.Iodinewaschosenbecauseitisahighatomicweightmaterialwhichdifferentiallyattenuatesx-raysbutisnonethelesswelltoleratedbythebody(itismostlyexcretedintheurine).Whenacatheteristhreadedintothepulmonaryarteryandaniodinatedsolutionejectedfromitstip,thepulmonaryarteriesarequicklyfirstopacifiedshowingarelativelyverticallyorientedbranchingpattern,originatingatthehilum.Normalarteriesprogressivelyreduceindiameteraftermultiplebranches.Usingacatheterinsertedbyanintravenousroutethroughtherightatriumandventricleandthenupwardintothemainpulmonaryartery,40cc.ofiodinatedcontrastfluidisinjectedtoopacifythepulmonaryarteriesbilaterally.Notetheverticalorientationofthemajorvesselsandhowtheybranchandgraduallytaper.Pulmonaryangiogram,venous

Venousangiogram

Anangiogramiscreatedbyinjectinganiodinesolutionintothebloodstreamofthepulmonaryarterythroughacatheter.Thepulmonaryarteriesarefirstopacified,thenastheiodinesolutioncollectsinthepulmonaryvenousstructures(now,ofcoursecontainingoxygenatedbloodhavingpassedthroughthelungalveoli),theanatomyoftheseveinsisrevealed.Thepulmonaryveinsliesomewhatmorehorizontalthanthearteriesandcoalescecentrallytowardtheleftatrium.Usingacatheterinsertedbyanintravenousroutethroughtherightatriumandventricleandthenupwardintothemainpulmonaryartery,40cc.ofiodinatedcontrastfluidisinjected.Theopacificationfirstfillsthepulmonaryarteriesbilaterallybutoverthenextfewsecondswashesintoandopacifiesthepulmonaryvenoustree.Notethatcomparedtotheverticalorientationofthearteries,thevenousdrainageismorehorizontalgatheringtowardtheleftatrium.Imagefinding:Lungnodules

Nodulesinthelungs

Observationofdiscreteabnormaldensitieswithinthelungfieldsaredescribedasnodules.Whenthedensityissimilartothatoftheribs,theycanbepresumedtobecalcified.Confirmationofthepresenceofcalciumcanbeobtainedquantitativelyfromcomputedtomographywhichmay,withitsgreaterquantitativesofttissuesensitivity,revealotherinapparentparenchymaldensities.Inthiscasetherearealsocalcificationsinthehilarnodesimplyingalow-gradechronicinflammatoryprocesssuchastuberculosis(Gohncomplex)orfungalinfection.Presenceofcalciuminthenodulesgenerallysignifiesabenign,inflammatoryprocessbutitshouldberecognizedthatmetastaticosteosarcomaandscarcarcinomas(withgenerallyeccentricallyplacedcalcium)aremalignancieswhichmaypresentasnodules.Imagefinding:Lungnodules,visibleonlyonCATscan

COMMENTSThis28yearoldmalewithahistoryofnon-seminomatoustesticularcarcinomawasbeingfollowedbyroutinechestX-rays.Thex-rayinthisexampleshowsverylittleevidenceofabnormalitybutthecomputedtomographyscandonesimultaneouslyshowmultiplenodulesanddemonstratetheincreasedsensitivityofthatcross-sectionaltechniqueforsmalltissuedensitynodulesinthelungs.SomeofthegreatervisibilityofthesenodulesonCTareduetothattechnique'sgreaterrangeofintensitydifferentiationofsoft-tissuedensities,butsomeoftheresultisalsoduetothecross-sectionalimagingplaneitproduceswhichavoidsconfusingoverlappingstructures.Imagefinding:Lungtumor,rightmiddlelobe

COMMENTSThisPAradiographdemonstratesalargewedge-shapeddensityintherightmiddlelobe.Alsonoteacoinlesionattherightcostophrenicangle.Therightmiddlelobelargedensityonbiopsywasdeterminedtobeametastasisfromcervicalcarcinoma.

Notethatthesharpupperboundaryoftherightmiddlelobetriangularmassistherightmiddlelobefissure.Inaddition,thereisenlargementoftherighthilarstructuresduetometastaseswithinthehilarlymphnodes.Imagefinding:Westermarksigns

COMMENTSTheWestermarkisaneponymindicatingtheabruptcutoffofpulmonaryvascularitydistaltoalargecentralpulmonaryembolus.Thepresumedmechanismbehindtheimagearisesfromthenearlycompleteobstructionofbloodflowtothepulmonaryarterydistaltotheembolicclot.Presumablythelackofflowtothesemoredistalvesselsresultsintheirradiographictransparencyandanappearanceofanabrupttruncationasisshowninthisexemplarycase.Imagefinding:Emphysema

Emphysema

Thefindingsofemphysemaincludehyperinflationofthelungs,lowdiaphragmpositions,andrelativeradiotransparencyofthepulmonaryparenchyma.Whenbullaeform,curvedparenchymallinesattheirbordersmaybepresent.Theemphysemamaybeasymmetricbutiscommonlynotedparticularlyintheupperlungfields.Hypodenselungs

Findingsarerelativelytransparentlungs(denser,ordarker,thannormalontheX-rayimagebecauseitismoretransparenttoX-rayphotons,moreofwhicharethenavailabletoexposetheimageandmakeitdarkerinthatregion)arisesfromtheabsenceofparenchymaltissue.Thismaybecausedeitherbyapneumothoraxordestructionofparenchymabyemphysemaandbullae.Withpneumothorax,asharplinedividingthelungparenchymaseparatingtheairinthethoraxcanbevisualizedparticularlyonexpirationfilms.Withbullousemphysematheremaybeincreasedcrowdingoftheremainingvasculatureandpulmonaryparenchymaasitiscrowdedintoasmallerfractionofthethoracicspace.Imagefinding:Hilaradenopathy,example1

COMMENTS

Enlargementofoneorbothhilamustdistinguishbetweenlymphadenopathyvs.vascularenlargement.Withfewexceptions,vascularenlargementproducesabranchingpatternatitsbordersandgenerallyisbilateral,whereaslymphadenopathyismoresphericalorelipsoidal.Bilaterallymphadenopathyoccurswithavarietyofimmunologicaldisordersaswellassarcoid,butunilateraladenopathyresultsfromeitherunilateralpulmonaryinfectionor,moreominously,malignanttumors.Imagefinding:Hilaradenopathy,example2Hilaradenopathy(duetosarcoid)

Hilaradenopathymustbedistinguishedfromenlargementofthehilarvasculature(suchasbypulmonaryhypertension).Hilarlymphnodesappearmorenodularand"lumpy"thanhilarvesselswhichusuallyretaintheirbranchingpatternwhenenlarged.Bilateralhilaradenopathyimpliesdiseasesthataregeneralizedandincludesarcoidandlymphoma.Imagefinding:PulmonaryedemaPulmonaryedema

(incongestiveheartfailure)

Normalbloodflowinthepulmonarycapillariesaresubjecttoavarietyofinfluences.Themeanhydrostaticintravascularpressureinthepulmonaryarteryisapproximately14mmHg.Thetransmuralvascularpressureistheintravascularpressureminustheintrapleuralpressureinthelargervessels.Pressureinthepulmonarycirculationissignificantlyinfluencedbygravity.Inerectsubjects,thedrivingpressureintheupperlung,wherealveolarpressureisgreaterthanpulmonaryvenouspressure,isthedifferencebetweenarterialandalveolarpressures.Inthelowerlung,thedrivingpressureisthedifferencebetweenarterialandvenouspressures.Intravascularpressureinthecapillariesispresumedtobe5-10mmHgandthecolloidalosmoticpressure,whichis25-30mmHg,servestokeepthealveolidry.Thissixtyyear-oldmalepresentedwithshortnessofbreathandorthopnea.Thex-rayshowscardiomegalyandmarkedprominenceofthepulmonaryvascularity.Inaddition,thereisincreaseddensityinthesmallvasculatureandalveolarspacesofthelungperipherally.Small,linearseptaldensitiesidentifiedasKerleyBlinesareahallmarkoftheseepageoffluidintotheinterstitiumduetoelevatedpulmonaryvenouspressure,whichinturnisduetoelevatedleftventricularend-diastolicpressurefromafailingleftventricle.Thecardiomegalycouldbepresumedtobeprimarilyduetoenlargementoftheleftventricleandleftatriumduetocontractilefailure,althoughtheenlargedcardiacsilhouettecouldalsoarisefromsomedegreeofpericardialfluid,whichcanberuledoutbyechocardiogram.Echocardiographywouldeasilypermitexaminationofsystolicleftventricularcontractilefunctionandrelativechambersizes.Thepulmonarypatternarisesfromthebackupofpressureinthepulmonaryvenousspaceandtransudateintotheinterstitialspacewhenthenoncoticpressureisexceeded.Kerleylines:

KerleyAlinesarestraight,longlinesinlungparenchymamostlymidwaybetweenhilumandpleura.Presenceoftheselinesdependontheaccumulationofabnormalamountsofedemaorothertissuewithintheperilymphaticconnectivetissuebutarenotduetodistentionofthelymphaticsthemselves.Theyarereversibleinpulmonaryedema,butirreversiblewhencausedbypneumoconiosisorlymphangiticcarcinoma.

KerleyBlinesareshort,straightlinesintheperipheryofthelunglyingapproximatelyperpendiculartothepleuralsurface.Blinesarecausedbyincreasedfluidortissueintheinterlobularsepta,primarilytheperilymphaticinterstitialtissue.Whentheedemaistransient,thelinesmayappearordisappearepisodically,butchronicchangesmayproducefibrosisorirreversiblelinessuchasinsarcoidosis,lymphangiticcarcincomatosis,orlymphoma.KerleyClinesconsistofafinenetworkofinterlacing,linearlinesoccasionallyseenininterstitialpulmonaryedemaandarecausedbythesuperimpositionofmanyKerleyBlines.Imagefinding:Pulmonaryinfiltrates

Pulmonaryconsolidation&infiltrates

Findingsofpulmonaryconsolidationarecharacterizedbyincreaseddensitypotentiallyinalobardistribution,althoughinmoresevereinfectionstheconsolidationsmayincludemultiplelobes.Othercausesofconsolidationincludebronchialobstructionwithgradualfillingoftheairspacesbyfluid,butoftenthelatteracutelyresultsinlossofvolume.Examinationoftheinfiltratepatternsbenefitsfromtwoorthogonalx-rayviewsandthusincludesthelateralfilm.Recently,highresolutioncomputedtomography(CT)imagingmaybetterdefinelocationandcharacteristicsofcertaintypesofinfiltratesandmaybethefirsttorecognizecavitationwhichcouldsignifyactivetuberculosis.Imagefinding:KerleyAandBlinesKerleylines

Patientswithcongestiveheartfailurecommonlywillhaveincreaseddensityoftheinterstitialmarkingsofthelungfields.VeryspecificpatternshavebeendescribedasKerley"B"or"A"lines.The"B"linesaremostcommonlycitedandwhenidentifiedimplythepresenceofinterstitialedemainthepulmonarysepta.TheKerley"B"linesareshort,horizontallinesperpendiculartothelateralaspectsofthelung.Theyarecommonlyaccompaniedbyothersignsofinterstitialedemasuchasbronchialcuffingandablurringofthemarginsofthepulmonaryvasculatureatthehila.KerleyAlinesarestraight,longlinesinlungparenchymamostlymidwaybetweenhilumandpleura.Presenceoftheselinesdependontheaccumulationofabnormalamountsofedemaorothertissuewithintheperilymphaticconnectivetissuebutarenotduetodistentionofthelymphaticsthemselves.Theyarereversibleinpulmonaryedema,butirreversiblewhencausedbypneumoconiosisorlymphangiticcarcinoma.KerleyBlinesareshort,straightlinesintheperipheryofthelunglyingapproximatelyperpendiculartothepleuralsurface.Blinesarecausedbyincreasedfluidortissueintheinterlobularsepta,primarilytheperilymphaticinterstitialtissue.Whentheedemaistransient,thelinesmayappearordisappearepisodically,butchronicchangesmayproducefibrosisorirreversiblelinessuchasinsarcoidosis,lymphangiticcarcincomatosis,orlymphoma.KerleyClinesconsistofafinenetworkofinterlacing,linearlinesoccasionallyseenininterstitialpulmonaryedemaandarecausedbythesuperimpositionofmanyKerleyBlines.Imagefinding:Airbronchogram,example1

Airbronchogram

Airbronchogramsoccurwhenthereispulmonaryinfiltrationoredemainthetissuesimmediatelyadjacenttothebronchi.Darkertubulardensitiescanbeseenwhentheinflammatoryprocessinvolvesthealveolibuthasnotfilledthebronchiwithfluid,andthereforedistinguishesthisdiseasefromcasesofatelectasisorpulmonaryedema.Imagefinding:Airbronchogram,example2

COMMENTS

Airbronchogramsaremostoftenassociatedwithinfectiousprocessesthatfillthealveolibutleavethesmallandmediumbronchiolesintactandair-filled.Thesesmalltubularradiatingdensitiesareusuallymorevisibleproximally.Imagefinding:PulmonarycavitationCOMMENTSCavitationinthepulmonaryparenchymaismorecommonwithinfectiousdiseasessuchastuberculosisorfungaletiologiesbutcanalsoarisefromtumors.Inthiscasethecausewasaprimarylungcancer.Imagefinding:Pleuraleffusion

COMMENTSTheradiographdemonstratesarelativelyflatopacifiedlineattherighthemidiaphragmcharacteristicofaneffusion.Inaddition,theuppersurfaceoftherightmiddlelobefissureismoresharplyvisiblewhichtendstooccurwhenthereisfluidinthatfissure.Thelateralradiographshowslossofthecostophrenicangleposteriorlyontheright.Theamountandfluidityoftheeffusioncanbebetterestimatedbyobtainingarightlateraldecubituswhichallowsthefluidtolayeroutalongtheribcage.Ultrasoundatthelowerthoracicboundarycanallowdirectedneedleplacementforevacuationforportionsofthepleuralfluidifneededfortherapeuticordiagnosticpurposes.Imagefinding:Pneumothorax

COMMENTSNotethemarkeddifferenceinX-raytransparency(density)betweentheleftandrightthoraciccavities.Thecompleteradio-translucency(manifestasgreaterfilmdensityordarkerlungfieldontheimage)ofthethoraxwithabsenceofvascularmarkingsischaracteristicofapneumothorax.Imagefinding:Atelectasis,rightupperlobe

AtelectasisRightUpperLobe

Rightupperlobeatelectasisusuallyproducesawedge-likedensityadjacenttotherightsideoftheupperspineandmediastinumonthefrontalfilm.Thetracheamaybesomewhatdrawntothatside.Lungvasculatureandmarkingsoftherightmiddleandrightlowerlobesstretchtofillthehemi-thoraxresultinginanangulationoftherightmiddlelobefissurewhichpivotsatthehilumwhereitisattached.Atelectasisimpliescollapseofthelungparenchymawithresorptionofitsaircontentandanincreaseinitsradiodensityresultinginaportionofthelungthatappearsmoreopaque(white).Collapseofasignificantamountoflungononesideofthehemithoraxmayleadtoamediastinalshifttowardthesideofthecollapse.Sincebronchiserveindividuallobestherearespecificappearancesthataccompanyindividuallobaratelectasis.Imagefinding:Atelectasis,rightmiddlelobe

Atelectasis-RightMiddleLobe

Atelectasisisthelossoflungvolumeandthereforeadirectsignisthedisplacementofinterlobularfissures.Generallythisisaccompaniedbyincreaseddensityandpossiblyelevationofthehemidiaphragm,mediastinaldisplacement,orcompensatoryover-inflation.Iftherehasbeenresorptionofairwithintheatelectaticsegment,thereisgenerallyanabsenceofairbronchograms.Thepatternofthespecificlobarorsegmentalcollapseproducesrelativelyspecificfindingsonthechestfilm,oftenrequiringbothPAandlateralfilmsforclearandspecificdefinition.PA(posterior-anterior)radiographofthisfemalepatient(notebreastshadowsbilaterally)showedobscurationofthelowerrightcardiacbordermergingwithopacificationofthelungfieldunderlyingtherightbreast.Becausetherightmiddlelobeisimmediatelyadjacenttothecardiacsilhouetteinthatpositioncollapseoropacificationoftherightmiddlelobewillmergedensitiesbetweenthelungandtheheartandthus,thenormalsharpboundarybetweenheartandlungislost.Thelateralradiographshowsthetriangularwedgeofdensitythatischaracteristicofrightmiddlelobeinfiltrate.Notethatthetrianglehasitsapexsuperiorlyandposteriorly.Withatelectasis,theangleofthatwedgewilldecreaseandtherightupperandlowerlobeswilloverinflateslightlytocompensateforlossoftherightmiddlelobevolume.Imagefinding:Atelectasis,leftupperlobe

Atelectasis

Atelectasisisthelossoflungvolumeandthereforeadirectsignisthedisplacementofinterlobularfissures.Generallythisisaccompaniedbyincreaseddensityandpossiblyelevationofthehemidiaphragm,mediastinaldisplacement,orcompensatoryover-inflation.Iftherehasbeenresorptionofairwithintheatelectaticsegment,thereisgenerallyanabsenceofairbronchograms.Thepatternofthespecificlobarorsegmentalcollapseproducesrelativelyspecificfindingsonthechestfilm,oftenrequiringbothPAandlateralfilmsforclearandspecificdefinition.Theradiographshowsmarkedincreaseddensityinthelefthemithoraxwhichobscurestheleftheartborder.Notethattheopacificationextendsfromtheupperportionofthethoraxtonearlythediaphragmandthatthediaphragmiselevatedontheleft.Lossoftheca