ImagingofthePlacenta（二）

胎盤影像學(xué)表現(xiàn)（二）PlacentaAccreta胎盤植入Duringtheprocessofplacentaldevelopmentandimplantation,adefectinthenormaldeciduabasalisfrompriorsurgeryorinstrumentationallowsabnormaladherenceorpenetrationofthechorionicvillitoorintotheuterinewall.由于胎盤植入所造成的手術(shù)或儀器使用常常導(dǎo)致基底膜部分缺失，使絨毛膜異常粘著或穿透入子宮壁Theextentofadherencetoandinvasionoftheplacentaltissuevaries:Super?cialinvasionofthebasalislayeristermedplacentaaccreta(approximately75%ofcases);deeperinvasionofthemyometriumistermedplacentaincreta;andevendeeperinvasioninvolvingtheserosaoradjacentpelvicorgansistermedplacentapercreta.根據(jù)胎盤植入的程度可分為以下幾種：表淺的基底膜受侵（約占75%）；子宮肌層受侵；子宮漿膜或子宮周圍組織受侵Thisabnormaladherenceoftheplacentatotheuteruscanresultincatastrophicintrapartumhemorrhageatthetimeofplacentaldelivery,oftennecessitatingemergenthysterectomy.胎盤植入常可導(dǎo)致分娩時(shí)出血PlacentaAccreta胎盤植入U(xiǎn)SandDopplerimaginghavebeenshowntobeeffectiveimagingstrategiesforthedetectionofplacentaaccretawhenappliedtoaclinicallyhigh-riskpopulation,suchasthosewithprioruterinesurgeryorplacentaprevia.

超聲和多普勒成像已經(jīng)證實(shí)是診斷胎盤植入的有效檢查手段，尤其是高危人群如曾有子宮手術(shù)史或前置胎盤史的患者

MRimagingismostusefulincaseswherethesonographic?ndingsareequivocalorwhentheplacentahasaposteriorlocation.MRI常應(yīng)用于超聲難以確診或胎盤后置時(shí)MRimagingfeaturesconsidereddiagnosticofplacentaaccretaincludeabnormaluterinebulging,heterogeneousplacentalsignalintensityonT2-weightedimages,andthepresenceofdarkintraplacentalbandsrelatedtolacunaeonT2-weightedimages.MRI診斷胎盤植入的特征主要是胎盤增生，包括子宮異常隆起,T2上盈盤信號不均，以及胎盤邊緣黑色的裂隙

(b)MRimageshowsintermediate-signal-intensityplacentaltissue(arrowhead)invadingthenormaldarkmyometrium(M)intheloweruterinesegment.(c)SagittalMRimageshowsobliterationofthenormaldarkmyometrium(M)posteriorly,withplacentaltissueofheterogeneoussignalintensity(arrowheads)penetratingthefullthicknessoftheuterinewall.B圖：MR顯示胎盤組織（箭頭所示）在子宮下方侵犯子宮正常肌層（M）C圖：MR顯示在子宮后份，正常低信號子宮肌層（M）被不均勻高信號（箭頭）侵襲bcaplacentaaccreta.(a)USimagesshowdisruptionofthenormalhypoechoicmyometrium(blackarrowheads)byinvadingplacentaltissue(whitearrowheads).B=bladder,P=placenta.A圖：超聲顯示正常的低回聲子宮肌層被胎盤組織（白色箭頭）植入。B=膀胱，P=胎盤GestationalTrophoblasticDisease

妊娠滋養(yǎng)細(xì)胞疾病Gestationaltrophoblasticdiseaseencompasseshydatidiformmoles,invasivemoles,andchoriocarcinoma.First-trimesterbleedingisoneofthemostcommonclinicalpresentationsforthisgroupofdisorders.Otherclinicalsignsandsymptomsincluderapiduterineenlargement,excessiveuterinesizeforgestationalage.妊娠滋養(yǎng)細(xì)胞疾病包括完全性葡萄胎、部分性葡萄胎及絨癌。其最常見的臨床癥狀是懷孕前月陰道出血，其它臨床癥狀包括子宮異常增大超過正常孕周胎盤體積。Thecommonfeatureforthisgroupofdisordersistheabnormalproliferationoftrophoblastictissuewithexcessiveproductionofβ–humanchorionicgonadotropin(β-hCG).這組疾病的典型特點(diǎn)是滋養(yǎng)層的增生，伴隨有人體絨毛膜促性腺激素（β-hCG）的過度分泌HydatidiformMole葡萄胎Hydatidiformmolesoccurin1ofevery1000–2000pregnanciesandareclassi?edintotwomajortypes—completeandpartial—withdistinctivehistologicandgeneticfeatures.每1000-2000例妊娠就有一次葡萄胎。葡萄胎可分為兩種類型：部分性和完全性，區(qū)別在于其組織學(xué)及遺傳基因的區(qū)別Thecompletehydatidiformmoleisthemostcommonformofgestationaltrophoblasticdisease.Completemolesresultfromfertilizationofanemptyovumwithsubsequentduplicationofthepaternalchromosomes.完全性葡萄胎是妊娠滋養(yǎng)細(xì)胞疾病中最常見的一種，由一個(gè)細(xì)胞核基因物質(zhì)缺失的空卵與一個(gè)單倍體精子受精，經(jīng)自身復(fù)制為二倍體Atpathologicanalysis,thetrophoblastictissueappearsasacomplexmulticysticmass,classicallydescribedasa“clusterofgrapes”病理學(xué)分析，其滋養(yǎng)層組織類似一復(fù)雜的多囊性腫塊，描述為“葡萄串”樣HydatidiformMole葡萄胎AtUS,completemolesappearasaheterogeneousechogenicendometrialmasswithmultiplevariable-sizedsmallanechoiccysts,givingtheappearanceofa“snowstorm”.Thereisnoidenti?ablefetaltissue.超聲顯示,完全性葡萄胎表現(xiàn)為不均勻回聲的子宮內(nèi)膜內(nèi)多個(gè)大小不等的無回聲囊腫,類似“暴風(fēng)雪”的外觀。沒有可識別的胎兒組織Partialmolesappearsimilartocompletemolesbutaredifferentiatedbythepresenceoffetaltissue.Distinctionbetweenthetwoformscanbedif?cultbutisoflimitedclinicalsigni?cance,asthemanagementissimilar.部分性葡萄胎超聲表現(xiàn)與完全性葡萄胎類似，但區(qū)別在于部分性葡萄胎有胎兒組織HydatidiformMole葡萄胎abA:USimageshowsamulticysticstructurewithintheuterus,a?ndingconsistentwithacompletemole.Noidenti?ablefetaltissuewaspresent.B:USimageshowsechogenicmaterial?llingthemajorityoftheuterinecavity.Adjacenttothismaterialisagestationalsaccontaininganembryo(arrowhead).These?ndingswereduetoapathologicallyprovedpartialA圖：超聲顯示子宮組織內(nèi)多發(fā)囊性病變，證實(shí)為完全性葡萄胎，且并沒有胎兒組織存在B圖：超聲顯示子宮腔內(nèi)異?；芈?，臨近病變可見一妊娠囊（白色箭頭），證實(shí)為部分性葡萄胎InvasiveMoleandChoriocarcinoma

侵襲性葡萄胎和絨毛膜癌Invasivemolesrepresentdeepgrowthoftheabnormaltissueintoandbeyondthemyometrium,sometimeswithpenetrationintotheperitoneumandparametrium.侵襲性葡萄胎侵襲程度較深，超過子宮肌層，部分侵襲至腹膜及子宮旁組織Choriocarcinomasaresimilartoinvasivemolesbutarecapableofmetastasizing,frequentlymanifestingwithlungandpelvicmetastases.Approximately50%ofchoriocarcinomasariseafteramolarpregnancy,25%ariseafterabortion,and25%ariseafteranormalpregnancy.絨毛膜癌與侵襲性葡萄胎類似但有遠(yuǎn)處轉(zhuǎn)移的特征，多轉(zhuǎn)移至肺及盆腔。大約50%的絨毛膜癌發(fā)生于葡萄胎之后，25%發(fā)生于流產(chǎn)之后，而25%則發(fā)生于正常妊娠后Invasivemolesandchoriocarcinomasarelargelyindistinguishableatimaging.Atsonography,bothappearasheterogeneous,echogenic,hypervascularmasses.Areasofintralesionnecrosisandhemorrhagecanbeseenwithinchoriocarcinoma.侵襲性葡萄胎和絨毛膜癌的影像學(xué)有明顯特征性，超聲顯示，這兩種病變均表現(xiàn)為不均勻回聲表現(xiàn)的多血管性腫塊。絨毛膜癌腫塊內(nèi)常出現(xiàn)壞死和出血。ChoriocarcinomaisonecaseinwhichCTisusedtoevaluateplacentaldisease,asthereisnodangeroffetalirradiation.However,theappearanceoftheprimarytumorisnonspeci?c,manifestingasheterogeneouspredominantlyhypoattenuatingintrauterinetissue.CTisparticularlyusefulforstagingchoriocarcinomabyallowingdetectionofdistantmetastases.由于沒有正常胎兒，絨毛膜癌是CT可以用來檢查的胎盤病變。原發(fā)腫瘤常常表現(xiàn)為不均勻的子宮內(nèi)低密度，CT常用于判定其分期InvasiveMoleandChoriocarcinoma

侵襲性葡萄胎和絨毛膜癌Althoughrarelyused,MRimagingcanhavearoleindemonstratingmyometrialandparametrialinvasion.MR常用來評價(jià)子宮肌層和子宮旁的受侵情況ChoriocarcinomaisusuallyseenasanintrauterinemasswithheterogeneoushighsignalintensityonT2-weightedimagesandmarkedenhancementonpostcontrastimages,?ndingsthatre?ectthehighvascularityofthetumor.Tumorvacularitycanalsobere?ectedbyfocalsignalvoidsonT1-andT2-weightedimages.絨毛膜癌常表現(xiàn)為不均勻的長T2信號，增強(qiáng)后明顯強(qiáng)化。由于其富血管性的病理特征，其常常表現(xiàn)為T1、T2上的流空信號。Myometrialinvasionisvisibleashigh-signal-intensityfociwithinthemyometrium,whichdemonstrateenhancementonpostcontrastimages.Enhancingparametrialsofttissueischaracteristicoflocalspread.MRimagingcanalsohelpdetectmetastaticdisease,particularlywithinthepelvicorgansandlymphnodes.子宮肌層受侵常表現(xiàn)為正常肌層內(nèi)的高信號組織，增強(qiáng)后明顯強(qiáng)化。而宮旁侵襲則表現(xiàn)為子宮旁的明顯強(qiáng)化的軟組織團(tuán)塊。MR還可用于評價(jià)淋巴結(jié)和遠(yuǎn)處轉(zhuǎn)移InvasiveMoleandChoriocarcinoma

侵襲性葡萄胎和絨毛膜癌Invasivemoleinapatientwithanelevatedβ-hCGlevel.B=bladder,R=rectum.(a)AxialT2-weightedMRimageshowsabrightmassintheuterinefundus.Themassdisruptsthenormaldarkmyometrialline(M)intheleftlateraluterus(arrowheads).(b)Gadolinium-enhancedMRimageshowsavidenhancementofthemass(arrowheads).侵襲性葡萄胎患者，伴有人體絨毛膜促性腺激素增多。B為膀胱，R為直腸。圖A：T2軸位表現(xiàn)為左側(cè)子宮底部肌層正常連續(xù)性中斷，可見一團(tuán)塊狀不均勻高信號（M）。圖B：增強(qiáng)后該腫塊呈明顯不均勻強(qiáng)化（箭頭）InvasiveMoleandChoriocarcinoma

侵襲性葡萄胎和絨毛膜癌abChoriocarcinoma.(a)SagittalT2-weightedMRimageshowsamassofheterogeneoussignalintensity(whitearrowheads)intheuterinefundus;themassinvadesintotheposterioruterinewall.Theinternalfocioflowsignalintensity(blackarrowhead)are?owvoids,whicharesuggestiveofmarkedvascularity.(b)Contrast-enhancedT1-weightedMRimageshowsavidenhancementofthemass(whitearrowheads).andthemasshascentrallowsignalintensity(blackarrowhead),whichrepresentsnecrosis.絨毛膜癌。圖A：矢狀位T2顯示子宮底部一不均勻的高信號腫塊侵入子宮肌層后壁（白色箭頭），內(nèi)可見流空信號為血管表現(xiàn)（黑色箭頭）B圖：增強(qiáng)后腫塊呈明顯不均勻強(qiáng)化（白色箭頭），內(nèi)可見片狀低信號（黑色箭頭）為壞死InvasiveMoleandChoriocarcinoma

侵襲性葡萄胎和絨毛膜癌abRetainedProductsofConception

產(chǎn)后妊娠物殘留ThediagnosisofRPOCissuspectedwhenroutineexaminationoftheplacentaatdeliveryrevealsanincompleteplacentaorwhenapregnantpatientpresentswithvaginalbleedinginthe?rsttrimesterandabnormalmaterialisappreciatedwithintheuterinecanal.產(chǎn)后妊娠物殘留多表現(xiàn)為產(chǎn)出胎盤不完整或妊娠早期陰道出血USistypicallytheimagingmodalityemployedwhenRPOCaresuspected.Transvaginalimagingisreportedlymoresensitiveandspeci?cthantransabdominalimaging.超聲尤其是經(jīng)陰道超聲比經(jīng)腹超聲對產(chǎn)后妊娠物殘留診斷更敏感AtMRimaging,RPOCtypicallyappearasheterogeneous-signal-intensitymassesonT1-andT2-weightedimages.Variableenhancementisobservedonpostcontrastimages.產(chǎn)后妊娠物殘留多表現(xiàn)為不均勻長T1不均勻長T2信號，增強(qiáng)后呈不均勻強(qiáng)化T2-weighted(a)andcontrast-enhancedspoiledgradient-recalledacquisitioninthesteadystate(b)MRimages,obtainedinanotherpatient,showamassintheuterinefundus(arrowheads)thatinvadesthemyometrium.ThemasshasheterogeneoussignalintensityontheT2-weightedimageandisisointenseontheT1-weightedimagewithuniformenhancement.T2和增強(qiáng)后MRI顯示子宮底部（箭頭）一腫塊，腫塊侵入子宮肌層，呈不均勻長T２信號，且增強(qiáng)后呈明顯強(qiáng)化RetainedProductsofConception

產(chǎn)后妊娠物殘留abNontrophoblasticplacentaltumorsarequiterare.Chorioangiomasarethemostcommon,occurring

inlessthan1%ofpregnancies.Placental

teratomasareextremelyrareandaresimilarinappearancetochorioangiomas,butaredifferentiatedbythepresenceofcalci?cations.非滋養(yǎng)層胎盤腫瘤比較少見，絨毛膜血管瘤是其中最常見的腫瘤，發(fā)生率少于１％妊娠。胎盤畸胎瘤也非常少見，且與絨毛膜血管瘤表現(xiàn)相似，但其特征性表現(xiàn)為鈣化NontrophoblasticPlacentalTumors

非滋養(yǎng)層胎盤腫瘤Giventhatthevastmajorityofchorioangiomasareincidentallyidenti?ed,thesonographiccharacteristicsarebestdescribed.Theselesionsappearaswell-circumscribed,rounded,hypoechoicormixed-echogenicitymassesprotrudingfromthefetalsideoftheplacenta.大多數(shù)絨毛膜血管瘤表現(xiàn)較典型，超聲多表現(xiàn)為邊緣光滑、類圓形、低回聲腫塊，病變多位于胎兒一側(cè)向腔內(nèi)突出MRimagingisusedonlyasanadjunctforfurtherevaluationinequivocalcases.ChorioangiomasareisointenseonT1-weightedimageswithincreasedsignalintensityonT2-weightedimages.FocalareasofincreasedsignalintensityonT1-andT2-weightedimagescorrespondtointralesionhemorrhage.MR多用于診斷無法確診的病例，絨毛膜血管瘤多表現(xiàn)為等T1長T2信號，內(nèi)可伴出血呈短T1短T2信號NontrophoblasticPlacentalTumors

非滋養(yǎng)層胎盤腫瘤Chorioangioma.(a)PowerDopplerimageshowsaheterogeneousmassonthefetalsurfaceoftheplacentawithinternalvascularityandalargefeedingvessel(arrow).(b)Gray-scaleUSimageshowsthelarge,well-ircumscribedmassarisingfromthesurfaceoftheplacenta(P)immediatelyadjacenttotheinsertionoftheumbilicalcord(C).絨毛膜血管瘤。A圖：多普勒超聲顯示胎盤內(nèi)胎兒面不均勻回聲腫塊，內(nèi)可見血管回聲（箭頭）B圖:腫塊邊界清楚，由胎盤的胎兒面長出，與臍帶（C）相鄰NontrophoblasticPlacentalTumors

非滋養(yǎng)層胎盤腫瘤abMetastases轉(zhuǎn)移瘤Involvementoftheplacentabymetastaticdiseaseisextremelyrare,withfewerthan100casesreportedintheliterature,toourknowledge.Placentalmetastasesarebelievedtoariseduetohematologicdisseminationoftumorcells,whichlodgeintheintervillousspaceoftheplac