孤立性肺結(jié)節(jié)

CT、PET-CT良惡性鑒別診斷Solitarypulmonarynodule:benignversusmalignant

DifferentiationwithCTandPET-CTAnnLeungandRobinSmithuis原文地址：孤立性肺結(jié)節(jié)的鑒別診斷，在臨床中經(jīng)常遇到。根據(jù)結(jié)節(jié)的良惡性差異，處理方法有很大差別。

在這篇文章中，我們主要探討CT和PET-CT的相關(guān)征象在孤立性肺結(jié)節(jié)良惡性鑒別診斷中的意義。Thedifferentialdiagnosisofasolitarypulmonarynoduleisbroadandmanagementdependsonwhetherthelesionisbenignormalignant.

InthisoverviewwewilldiscusssomeofthenewfeaturesthatcanhelptodifferentiatebetweenbenignandmalignantnodulesbaseduponCTandPET-CTfindings目錄（contents）CT征象鈣化大小生長(zhǎng)速度形狀邊界充氣支氣管征實(shí)性和磨玻璃成分強(qiáng)化特征PET-CT征象結(jié)論CT:benignversusmalignantCalcification

SizeGrowth

Shape

Margin

AirBronchogramsign

SolidandGround-glasscomponents

Contrastenhancement

PET-CT:benignversusmalignantConclusion

CalcificationDiffuse,central,laminatedorpopcorncalcificationsarebenignpatternsofcalcification.

Thesetypesofcalcificationareseeningranulomatousdiseaseandhamartomas.

Allotherpatternsofcalcificationshouldnotberegardedasasignofbenignity.Theexceptiontotheruleaboveiswhenpatientsareknowntohaveaprimarytumor.

Forinstancethediffusecalcificationpatterncanbeseeninpatientswithosteosarcomaorchondrosarcoma.

SimilarlythecentralandpopcornpatterncanbeseeninpatientswithGI-tumorsandpatientswhopreviouslyhadchemotherapy.結(jié)節(jié)大小

結(jié)節(jié)大小與惡性可能性之間的關(guān)系孤立性肺結(jié)節(jié)（SPN）定義：肺實(shí)質(zhì)內(nèi)小于等于3cm的病灶（需除外肺不張和腫大的淋巴結(jié)）。大于3cm的病灶稱(chēng)為腫塊（mass）。之所以這樣定義，是因?yàn)榇笥?cm的病灶多為惡性，而更小的病灶可能是良心或惡性。Swensen.etal研究了SPN大小與惡性可能性之間的關(guān)系（上圖），結(jié)論是小的結(jié)節(jié)，良性可能性大。超過(guò)2000例小于4mm的結(jié)節(jié)，無(wú)一例屬于惡性。SizeAsolitarypulmonarynodule(SPN)isdefinedasasingleintraparenchymallesionlessthan3cminsizeandnotassociatedwithatelectasisorlymphadenopathy.

Alesiongreaterthan3cmindiameteriscalledamass.

Thisdistinctionismade,becauselesionsgreaterthan3cmareusuallymalignant,whilesmallerlesionscanbeeitherbenignormalignant.SwensenetalstudiedtherelationshipbetweenthesizeofaSPNandthechanceofmalignancyinacohortathighriskforlungcancer(1).

Theirfindingsarelistedinthetableontheleft.

Theyconcludedthatbenignnoduledetectionrateishigh,especiallyiflesionsaresmall.

Oftheover2000nodulesthatwerelessthan4mminsize,nonewasmalignantGrowthComparisonwithpriorimagingstudiesisoftenthemostusefulproceduretodeterminetheimportanceofthefindingofaSPN,sincestabilityover2yearsishighlyassociatedwithbenignity.形狀

左：橫斷圖像；右：冠狀重建圖像。三維比值=（最大）橫徑/長(zhǎng)徑日本的相關(guān)研究證實(shí)，多角形、三維比值大于1.78的結(jié)節(jié)，多為良性。在肺的外圍、胸膜下的結(jié)節(jié)也多為良性。三維比值=（最大）橫徑/長(zhǎng)徑。大的三維比值說(shuō)明病灶的形狀是扁平的（是“片”不是“塊”），這是良性的特征。ShapeJapanesescreeningstudiesshowedthatapolygonalshapeandathree-dimensionalratio>1.78wasasignofbenignity(2,3).

Apolygonalshapemeansthatthelesionhasmultiplefacets(multi-sided).

Aperipheralsubpleurallocationwasalsoasignofbenignityinthisstudy.Thethree-dimensionalratioismeasuredbyobtainingthemaximaltransversedimensionanddividingitbythemaximalverticaldimension.

Alargethree-dimensionalratioindicatesthatthelesionisrelativelyflat,whichisabenignsign.MarginCoronaradiatasign-highlyassociatedwithmalignancy(figure)Lobulatedorscallopedmargins-intermediateprobabilitySmoothmargins-morelikelybenignunlessmetastaticinorigin充氣支氣管征最新研究表明，有充氣支氣管征的結(jié)節(jié)多為惡性。主要見(jiàn)于BAC（細(xì)支氣管肺泡癌）和腺癌。上圖顯示充氣的支氣管呈線樣（粗箭）或囊狀（細(xì)箭）透亮區(qū)，這是支氣管走向不同造成的。AirBronchogramsignRecentstudieshaveshowedthatanairbronchogramismorecommonlyseeninmalignantpulmonarynodules.

ItismostcommonlyseeninBAC(bronchoalveolarcellcarcinoma)andadenocarcinoma.Thecaseontheleftshowsanairbronchogramseenasalinearlucency(broadarrow)andasamorecysticlucency(smallarrow)duetothefactthatthebronchusisseenenface.Onthelefttwosolitarypulmonarynodules.

Baseduponthemorphology,whichlesionhasthemostmalignantfeatures?Thelesiononthefarlefthasaspicuatedmarginandhaslucencieswithinit.

Thelesionnexttoitislobulatedincontourandhassomespiculesradiatingtothepleura.

Itishoweverhomogeneousinattenuation.

Basedonthesefindingsweshouldbemostconcernedthatthelesiononthefarleftismalignant.

Itprovedtobeanadenocarcinoma,whiletheotheronewasafungalinfection.

Thelucenciesandfrankairbronchogramsshouldnotmisleadyouinthinkingthatitprobablyisinfection.實(shí)性和磨玻璃成分一項(xiàng)研究表明：結(jié)節(jié)內(nèi)含有磨玻璃樣成分的，更傾向于屬于惡性。結(jié)節(jié)內(nèi)既含有部分實(shí)性成分，又含有磨玻璃成分的，為惡性的可能性為63%。沒(méi)有實(shí)性成分，只有磨玻璃成分的，惡性可能性有18%。全部為實(shí)性成分的，惡性可能性為7%。SolidandGround-glasscomponentsAnotherresultfromscreeningstudiesisthatnodulescontainingaground-glasscomponentaremorelikelytobemalignant.

Partlysolidlesionswithground-glasscomponentshadamalignancyrateof63%.Nonsolid-onlyground-glasslesionshadamalignancyrateof18%.Onlysolidlesionshadamalignancyrateofonly7%.Onthefarleftalesionthatonlyhasaground-glassappearanceandnexttoitalesionthathasbothground-glassandsolidcomponents.

Thelikelihoodofmalignancyis1:5forthelesiononthefarleftand2:3forthelesionwithbothground-glassandsolidcomponents.強(qiáng)化特征增強(qiáng)掃描強(qiáng)化程度小于15HU的，有99%的可能性為良性。平掃后增強(qiáng)掃描，每一分鐘掃描一次，連續(xù)4次。結(jié)節(jié)滿足以下條件者，才能采用這種方法評(píng)價(jià)：結(jié)節(jié)>5mm相對(duì)呈球形內(nèi)部均質(zhì)，沒(méi)有壞死、脂肪和鈣化圖像無(wú)明顯偽影ContrastenhancementContrastenhancementlessthan15HUhasaveryhighpredictivevalueforbenignity(99%).

Afterabaselinescan,4consecutivescansat1minuteintervalareperformed.

Thisappliesonlyfornoduleswiththefollowingselectioncriteria:Nodule>5mmRelativelysphericalHomogeneous,nonecrosis,fatorcalcificationNomotionorbeamhardeningartifactsPET-CT:benignversusmalignantPET-CTplaysanincreasinglyimportantroleintheevaluationofsolitarynodules.Whenyouper