,孤立性肺結(jié)節(jié)CT、PET-CT良惡性鑒別診斷,Solitarypulmonarynodule:benignversusmalignantDifferentiationwithCTandPET-CTAnnLeungandRobinSmithuis原文地址：http:/www.radiologyassistant.nl/en/460f9fcd50637,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:benignversusmalignantCalcificationSizeGrowthShapeMarginAirBronchogramsignSolidandGround-glasscomponentsContrastenhancementPET-CT:benignversusmalignantConclusion,鈣化,良性鈣化征象：彌漫性中心性層狀爆米花樣彌漫性、中心性、層狀及爆米花樣鈣化多見于良性結(jié)節(jié)。主要見于肉芽腫性疾病和錯(cuò)構(gòu)瘤。其他類型鈣化多見于惡性結(jié)節(jié)，不應(yīng)該認(rèn)為屬于良性表現(xiàn)。在已知有原發(fā)腫瘤存在的情況下，其鈣化類型不一定適用此結(jié)論。例如：骨肉瘤或軟骨肉瘤的病人，其鈣化多表現(xiàn)為彌漫性；同樣的，中心性和爆米花樣鈣化也可見于胃腸道腫瘤或接受過化療的病人。,Calcification,Diffuse,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2000例小于4mm的結(jié)節(jié)，無一例屬于惡性。,Size,Asolitarypulmonarynodule(SPN)isdefinedasasingleintraparenchymallesionlessthan3cminsizeandnotassociatedwithatelectasisorlymphadenopathy.Alesiongreaterthan3cmindiameteriscalledamass.Thisdistinctionismade,becauselesionsgreaterthan3cmareusuallymalignant,whilesmallerlesionscanbeeitherbenignormalignant.SwensenetalstudiedtherelationshipbetweenthesizeofaSPNandthechanceofmalignancyinacohortathighriskforlungcancer(1).Theirfindingsarelistedinthetableontheleft.Theyconcludedthatbenignnoduledetectionrateishigh,especiallyiflesionsaresmall.Oftheover2000nodulesthatwerelessthan4mminsize,nonewasmalignant,生長速度,與以前的CT片進(jìn)行比較，在結(jié)節(jié)定性方面具有重要意義。超過2年無變化的結(jié)節(jié)多為良性。,Growth,ComparisonwithpriorimagingstudiesisoftenthemostusefulproceduretodeterminetheimportanceofthefindingofaSPN,sincestabilityover2yearsishighlyassociatedwithbenignity.,形狀,左：橫斷圖像；右：冠狀重建圖像。三維比值=（最大）橫徑/長徑日本的相關(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/長徑。大的三維比值說明病灶的形狀是扁平的（是“片”不是“塊”），這是良性的特征。,Shape,Japanesescreeningstudiesshowedthatapolygonalshapeandathree-dimensionalratio1.78wasasignofbenignity(2,3).Apolygonalshapemeansthatthelesionhasmultiplefacets(multi-sided).Aperipheralsubpleurallocationwasalsoasignofbenignityinthisstudy.Thethree-dimensionalratioismeasuredbyobtainingthemaximaltransversedimensionanddividingitbythemaximalverticaldimension.Alargethree-dimensionalratioindicatesthatthelesionisrelativelyflat,whichisabenignsign.,邊緣,輻射冠征：絕大多數(shù)都為惡性（上圖：惡性病灶周圍的輻射冠征-毛刺）。病灶邊緣呈分葉狀的，可以是良性或惡性邊緣光滑，多為良性。,Margin,Coronaradiatasign-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。,AirBronchogramsign,Recentstudieshaveshowedthatanairbronchogramismorecommonlyseeninmalignantpulmonarynodules.ItismostcommonlyseeninBAC(bronchoalveolarcellcarcinoma)andadenocarcinoma.Thecaseontheleftshowsanairbronchogramseenasalinearlucency(broadarrow)andasamorecysticlucency(smallarrow)duetothefactthatthebronchusisseenenface.,圖中兩個(gè)SPN，根據(jù)形態(tài)表現(xiàn)，哪個(gè)更像惡性的？左邊的結(jié)節(jié)邊緣呈毛刺狀，內(nèi)部有透亮區(qū)；右側(cè)者呈分葉狀，邊緣毛刺并與胸膜粘連，但是內(nèi)部均質(zhì)?；谏厦娴谋憩F(xiàn)，我們認(rèn)為左側(cè)者更像惡性的。最終證實(shí)，左側(cè)者為腺癌，右側(cè)為真菌感染。,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-glasscomponents,Anotherresultfromscreeningstudiesisthatnodulescontainingaground-glasscomponentaremorelikelytobemalignant.Partlysolidlesionswithground-glasscomponentshadamalignancyrateof63%.Nonsolid-onlyground-glasslesionshadamalignancyrateof18%.Onlysolidlesionshadamalignancyrateofonly7%.,左側(cè)者只有磨玻璃成分；右側(cè)者既有磨玻璃成分又含有實(shí)性成分。左側(cè)者惡性可能性為1/5;右側(cè)者惡性可能性為2/3.,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)，沒有壞死、脂肪和鈣化圖像無明顯偽影,Contrastenhancement,Contrastenhancementlessthan15HUhasaveryhighpredictivevalueforbenignity(99%).Afterabaselinescan,4consecutivescansat1minuteintervalareperformed.Thisappliesonlyfornoduleswiththefollowingselectioncriteria:Nodule5mmRelativelysphericalHomogeneous,nonecrosis,fatorcalcificationNomotionorbeamhardeningartifacts,PET-CT,PET-CT在實(shí)性結(jié)節(jié)評(píng)價(jià)方面起著越來越重要的作用。在進(jìn)行PET-CT檢查時(shí)，你必須意識(shí)到：PET-CT敏感性高達(dá)95%，但特異性只有81%；肉芽腫性疾病可以呈假陽性；小于10mm的結(jié)節(jié)、良性腫瘤以及低度惡性的結(jié)節(jié)包括支氣管肺泡癌可以呈假陰性。上圖為一例腺癌病人，結(jié)節(jié)并不顯示為高代謝狀態(tài)，所以呈假陰性。,PET-CT:benignversusmalignant,PET-CTplaysanincreasinglyimportantroleintheevaluationofsolitarynodules.WhenyouperformPET-CT,youhavetorealizethefollowing:PEThasaveryhighsensitivity95%,butalesserspecificityofonly81%PETisfalsepositiveingranulomatousdiseasePETisusuallyfalsenegativeinsize10mmandlow-grademalignancyincludingbronchoalveolarcarcinomaandcarcinoidWiththesespecificitynumbers,therewillbefalsepositivesinabout20%,dependingonthebackgroundprev