孤立性肺结节PETCT良恶性鉴别诊疗讲义

孤立性肺结节PETCT良恶性鉴别诊疗孤立性肺结节的鉴别诊断，在临床中经常遇到。根据结节的良恶性差异，处理方法有很大差别。

在这篇文章中，我们主要探讨CT和PET-CT的相关征象在孤立性肺结节良恶性鉴别诊断中的意义。Thedifferentialdiagnosisofasolitarypulmonarynoduleisbroadandmanagementdependsonwhetherthelesionisbenignormalignant.

InthisoverviewwewilldiscusssomeofthenewfeaturesthatcanhelptodifferentiatebetweenbenignandmalignantnodulesbaseduponCTandPET-CTfindings目录（contents）CT征象钙化大小生长速度形状边界充气支气管征实性和磨玻璃成分强化特征PET-CT征象结论CT:benignversusmalignantCalcification

SizeGrowth

Shape

Margin

AirBronchogramsign

SolidandGround-glasscomponents

Contrastenhancement

PET-CT:benignversusmalignantConclusion

钙化良性钙化征象：弥漫性中心性层状爆米花样弥漫性、中心性、层状及爆米花样钙化多见于良性结节。主要见于肉芽肿性疾病和错构瘤。其他类型钙化多见于恶性结节，不应该认为属于良性表现。在已知有原发肿瘤存在的情况下，其钙化类型不一定适用此结论。例如：骨肉瘤或软骨肉瘤的病人，其钙化多表现为弥漫性；同样的，中心性和爆米花样钙化也可见于胃肠道肿瘤或接受过化疗的病人。CalcificationDiffuse,central,laminatedorpopcorncalcificationsarebenignpatternsofcalcification.

Thesetypesofcalcificationareseeningranulomatousdiseaseandhamartomas.

Allotherpatternsofcalcificationshouldnotberegardedasasignofbenignity.Theexceptiontotheruleaboveiswhenpatientsareknowntohaveaprimarytumor.

Forinstancethediffusecalcificationpatterncanbeseeninpatientswithosteosarcomaorchondrosarcoma.

SimilarlythecentralandpopcornpatterncanbeseeninpatientswithGI-tumorsandpatientswhopreviouslyhadchemotherapy.结节大小结节大小与恶性可能性之间的关系孤立性肺结节（SPN）定义：肺实质内小于等于3cm的病灶（需除外肺不张和肿大的淋巴结）。大于3cm的病灶称为肿块（mass）。之所以这样定义，是因为大于3cm的病灶多为恶性，而更小的病灶可能是良心或恶性。Swensen.etal研究了SPN大小与恶性可能性之间的关系（上图），结论是小的结节，良性可能性大。超过2000例小于4mm的结节，无一例属于恶性。SizeAsolitarypulmonarynodule(SPN)isdefinedasasingleintraparenchymallesionlessthan3cminsizeandnotassociatedwithatelectasisorlymphadenopathy.

Alesiongreaterthan3cmindiameteriscalledamass.

Thisdistinctionismade,becauselesionsgreaterthan3cmareusuallymalignant,whilesmallerlesionscanbeeitherbenignormalignant.SwensenetalstudiedtherelationshipbetweenthesizeofaSPNandthechanceofmalignancyinacohortathighriskforlungcancer(1).

Theirfindingsarelistedinthetableontheleft.

Theyconcludedthatbenignnoduledetectionrateishigh,especiallyiflesionsaresmall.

Oftheover2000nodulesthatwerelessthan4mminsize,nonewasmalignant生长速度与以前的CT片进行比较，在结节定性方面具有重要意义。超过2年无变化的结节多为良性。GrowthComparisonwithpriorimagingstudiesisoftenthemostusefulproceduretodeterminetheimportanceofthefindingofaSPN,sincestabilityover2yearsishighlyassociatedwithbenignity.形状左：横断图像；右：冠状重建图像。三维比值=（最大）横径/长径日本的相关研究证实，多角形、三维比值大于1.78的结节，多为良性。在肺的外围、胸膜下的结节也多为良性。三维比值=（最大）横径/长径。大的三维比值说明病灶的形状是扁平的（是“片”不是“块”），这是良性的特征。ShapeJapanesescreeningstudiesshowedthatapolygonalshapeandathree-dimensionalratio>1.78wasasignofbenignity(2,3).

Apolygonalshapemeansthatthelesionhasmultiplefacets(multi-sided).

Aperipheralsubpleurallocationwasalsoasignofbenignityinthisstudy.Thethree-dimensionalratioismeasuredbyobtainingthemaximaltransversedimensionanddividingitbythemaximalverticaldimension.

Alargethree-dimensionalratioindicatesthatthelesionisrelativelyflat,whichisabenignsign.边缘辐射冠征：绝大多数都为恶性（上图：恶性病灶周围的辐射冠征--毛刺）。病灶边缘呈分叶状的，可以是良性或恶性边缘光滑，多为良性。MarginCoronaradiatasign-highlyassociatedwithmalignancy(figure)Lobulatedorscallopedmargins-intermediateprobabilitySmoothmargins-morelikelybenignunlessmetastaticinorigin充气支气管征最新研究表明，有充气支气管征的结节多为恶性。主要见于BAC（细支气管肺泡癌）和腺癌。上图显示充气的支气管呈线样（粗箭）或囊状（细箭）透亮区，这是支气管走向不同造成的。AirBronchogramsignRecentstudieshaveshowedthatanairbronchogramismorecommonlyseeninmalignantpulmonarynodules.

ItismostcommonlyseeninBAC(bronchoalveolarcellcarcinoma)andadenocarcinoma.Thecaseontheleftshowsanairbronchogramseenasalinearlucency(broadarrow)andasamorecysticlucency(smallarrow)duetothefactthatthebronchusisseenenface.图中两个SPN，根据形态表现，哪个更像恶性的？左边的结节边缘呈毛刺状，内部有透亮区；右侧者呈分叶状，边缘毛刺并与胸膜粘连，但是内部均质。基于上面的表现，我们认为左侧者更像恶性的。最终证实，左侧者为腺癌，右侧为真菌感染。Onthelefttwosolitarypulmonarynodules.

Baseduponthemorphology,whichlesionhasthemostmalignantfeatures?Thelesiononthefarlefthasaspicuatedmarginandhaslucencieswithinit.

Thelesionnexttoitislobulatedincontourandhassomespiculesradiatingtothepleura.

Itishoweverhomogeneousinattenuation.

Basedonthesefindingsweshouldbemostconcernedthatthelesiononthefarleftismalignant.

Itprovedtobeanadenocarcinoma,whiletheotheronewasafungalinfection.

Thelucenciesandfrankairbronchogramsshouldnotmisleadyouinthinkingthatitprobablyisinfection.实性和磨玻璃成分一项研究表明：结节内含有磨玻璃样成分的，更倾向于属于恶性。结节内既含有部分实性成分，又含有磨玻璃成分的，为恶性的可能性为63%。没有实性成分，只有磨玻璃成分的，恶性可能性有18%。全部为实性成分的，恶性可能性为7%。SolidandGround-glasscomponentsAnotherresultfromscreeningstudiesisthatnodulescontainingaground-glasscomponentaremorelikelytobemalignant.

Partlysolidlesionswithground-glasscomponentshadamalignancyrateof63%.Nonsolid-onlyground-glasslesionshadamalignancyrateof18%.Onlysolidlesionshadamalignancyrateofonly7%.左侧者只有磨玻璃成分；右侧者既有磨玻璃成分又含有实性成分。左侧者恶性可能性为1/5;右侧者恶性可能性为2/3.Onthefarleftalesionthatonlyhasaground-glassappearanceandnexttoitalesionthathasbothground-glassandsolidcomponents.

Thelikelihoodofmalignancyis1:5forthelesiononthefarleftand2:3forthelesionwithbothground-glassandsolidcomponents.强化特征增强扫描强化程度小于15HU的，有99%的可能性为良性。平扫后增强扫描，每一分钟扫描一次，连续4次。结节满足以下条件者，才能采用这种方法评价：结节>5mm相对呈球形内部均质，没有坏死、脂肪和钙化图像无明显伪影ContrastenhancementContrastenhancementlessthan15HUhasaveryhighpredictivevalueforbenignity(99%).

Afterabaselinescan,4consecutivescansat1minuteintervalareperformed.

Thisappliesonlyfornoduleswiththefollowingselectioncriteria:Nodule>5mmRelativelysphericalHomogeneous,nonecrosis,fatorcalcificationNomotionorbeamhardeningartifactsPET-CTPET-CT在实性结节评价方面起着越来越重要的作用。在进行PET-CT检查时，你必须意识到：PET-CT敏感性高达95%，但特异性只有81%；肉芽肿性疾病可以呈假阳性；小于10mm的结节、良性肿瘤以及低度恶性的结节包括支气管肺泡癌可以呈假阴性。上图为一例腺癌病人，结节并不显示为高代谢状态，所以呈假阴性。PET-CT:benignversusmalignantPET-CTplaysanincreasinglyimportantroleintheevalua