腦靜脈血栓形成影像學(xué)

CerebralVenousThrombosis

BarbaraSimons,GeertLycklamaaNijeholtandRobinSmithuis

RadiologydepartmentoftheMedicalCentreHaaglandenintheHagueandtheRijnlandhospitalinLeiderdorp,theNetherlands腦靜脈性栓塞形成Introduction

Whentothinkofvenousthrombosis

Denseclotsign

Emptydeltasign

AbsenceofnormalflowvoidonMR

Venousinfarction

Imaginginsuspectedthrombosis

CT-venography

MR-venography

DSA

PitfallsinCT

ArachnoidGranulations

Mimickofdenseclotsign

Pseudoemptydeltasign

Wrongbolustiming

PitfallsinMRI

Hypoplastictransversesinus

Lowsignalintensityinthrombus

Flowvoidoncontrast-enhancedMR

Chronicduralsinusthrombosisandrelatedsyndromes

DAVF

ThrombosisandincreasedCSFpressure

Venousterritories

PublicationdateOctober21,2010Cerebralvenousthrombosisisanimportantcauseofstrokeespeciallyinchildrenandyoungadults.

Itismorecommonthanpreviouslythoughtandfrequentlymissedoninitialimaging.

Itisadifficultdiagnosisbecauseofitsnonspecificclinicalpresentationandsubtleimagingfindings.

Inthisarticlewewillfocuson:Findingsonroutineimagingthatshouldmakeyouthinkofunsuspectedvenousthrombosis.Howtoimagepatientsinsuspectedvenousthrombosis.Pitfalls.此時應(yīng)想到靜脈栓塞可能致密斑塊征空三角征MR上正常流空征消失靜脈性腦梗塞疑似此病的成像方法CT靜脈成像MR靜脈成像DSACT陷阱蛛網(wǎng)膜顆?？崴浦旅苣龎K征假性空三角征錯誤的團注時間MRI陷阱橫竇發(fā)育不良血栓內(nèi)低信號強度MR對比增強時的流空硬膜竇栓塞臨床與相關(guān)綜合征DAWF（硬膜動靜脈瘺）栓塞和腦脊液壓力增高靜脈分布圖靜脈性腦梗塞是中風(fēng)的重要原因，尤其是在兒童或年輕人。它比以前更常見而且常常在最初的成像中漏診由于臨床上缺少特征而且影像所見微妙，因而診斷困難這里主要討論的內(nèi)容：*提示可疑靜脈性腦梗塞的常規(guī)影像學(xué)表現(xiàn)*疑為靜脈性腦梗塞如何進一步進行影像學(xué)檢查*陷阱Cerebralvenousthrombosisislocatedindescendingorderinthefollowingvenousstructures:Majorduralsinuses:

Superiorsagittalsinus,transverse,straightandsigmoidsinuses.Corticalveins:VeinofLabbe,whichdrainsthetemporallobe.VeinofTrolard,whichisthelargestcorticalveinthatdrainsintothesuperiorsagittalsinus.

Deepveins:

Internalcerebralandthalamostriateveins.

Cavernoussinus.

Clinicallypatientswithcerebralvenousthrombosispresentwithvariablesymptomsrangingfromheadachetoseizureandcomainseverecases.

Inneonatesshockanddehydrationisacommoncauseofvenousthrombosis.

Inolderchildrenitisoftenlocalinfection,suchasmastoiditis,orcoagulopathy.

Inadults,coagulopathiesisthecausein70%andinfectionisthecausein10%ofcases.

Inwomen,oralcontraceptiveuseandpregnancyarestrongriskfactors.重要的解剖與臨床腦靜脈性栓塞多位于以下的靜脈結(jié)構(gòu)*主要靜脈竇：上矢狀竇、橫竇、直竇和乙狀竇。*皮質(zhì)靜脈：Labbe靜脈，顳葉的引流靜脈；Trolard靜脈，為最大的皮質(zhì)靜脈，匯入上矢狀竇。*深靜脈：大腦內(nèi)靜脈和丘腦紋狀體靜脈。*海綿竇。*臨床上，腦靜脈栓塞可有多種癥狀，嚴重病例如頭痛、癲癇、昏迷。*新生兒休克或脫水是腦靜脈栓塞常見的原因。*在兒童，局灶性的感染如中耳炎或凝血障礙。*成人中，70%的病因為凝血障礙；10%源自感染女性，口服避孕藥與妊娠也是其危險因素。WhentothinkofvenousthrombosisOnaroutinenon-enhancedMRorCTyoushouldthinkofthepossibilityofvenousthrombosiswhenyousee:DirectsignsofathrombusInfarctioninanon-arteriallocation,especiallyifitisbilateralandhemorrhagicCorticalorperipherallobarhemorrhageCorticaledemaVenousthrombosishasanonspecificpresentationandthereforeitisimportanttorecognizesubtleimagingfindingsandindirectsignsthatmayindicatethepresenceofthrombosis.Althoughthesefindingsareoftenpresentoninitialscans,theyarefrequentlydetectedonlyinretrospect.

Clinicallypatientswithvenousthrombosisoftenpresentwithseizures,whichisnotasymptominpatientswithanarterialinfarction.什么情況下考慮靜脈竇栓塞呢？？在常規(guī)的CT或MR平掃圖像若有下面的表現(xiàn)應(yīng)該想到靜脈性腦栓塞可能：*靜脈血栓的直接征象*腦梗塞非動脈性的常見部位，尤其是為雙側(cè)性、出血性*皮質(zhì)或周圍腦葉的出血*腦皮質(zhì)水腫腦靜脈血栓形成為非特異性的表現(xiàn)，因此，認識這些微妙的影像學(xué)的表現(xiàn)以及間接征象很重要，它可以指出血栓形成之存在。靜脈血栓形成的病人在臨床上常表現(xiàn)癲癇，但這不是動脈性腦梗塞病人出現(xiàn)的癥狀。盡管這些表現(xiàn)經(jīng)常地出現(xiàn)在最初的掃描中，但卻經(jīng)常只是在回顧中發(fā)現(xiàn)這些異常。11、透明隔靜脈12、丘腦紋狀體靜脈13、大腦內(nèi)靜脈14、大腦大靜脈15、基底靜脈24、直竇25、蝶頂竇26、海綿竇27、海綿間竇29、巖上竇30、巖下竇1、上矢狀竇2、下矢狀竇3、竇匯4、橫竇5、乙狀竇6、頸靜脈球7、頸內(nèi)靜脈8、淺表皮層靜脈9、靜脈10、大腦中淺靜脈Trolard靜脈Labbe靜脈Rosenthal基底靜脈附加：正常解剖圖與靜脈栓塞的病理解剖示意圖正常腦靜脈竇示意圖上矢狀竇及腦靜脈栓塞伴發(fā)的腦腫脹及損傷損傷的腦組織出血Denseclotsign（1）DirectvisualizationofaclotinthecerebralveinsonanonenhancedCTscanisknownasthedenseclotsign.

Itisseeninonlyonethirdofcases.

Normallyveinsareslightlydenserthanbraintissueandinsomecasesitisdifficulttosaywhethertheveinisnormalortoodense(seepitfalls).

Inthesecasesacontrastenhancedscanisnecessarytosolvethisproblem.*致密凝塊征（1）：CT平掃見到的腦靜脈血栓的直接表現(xiàn)，出現(xiàn)率為1/3.*正常的腦靜脈表現(xiàn)為密度較腦組織輕度高，但有些病例的正常與否判斷確有困難（參見陷阱）。*CT增強掃描可準確地解決該問題。Denseclotsign(2)

Visualizationofathrombosedcorticalveinthatisseenasalinearorcord-likedensity,isalsoknownasthecordsign.

Anothertermthatisfrequentlyused,isthedensevesselsign.Denseclotsign(3)

Ontheleftimagesofapatientwithahemorrhagicinfarctioninthetemporallobe(redarrow).

Noticethedensetransversesinusduetothrombosis(bluearrows).*致密凝塊征（2）：CT平掃見到的腦皮質(zhì)靜脈血栓的表現(xiàn)，呈線樣或繩索樣高密度影，即所謂繩索征（上圖

紅箭）。也有稱其為致密血管征。*致密凝塊征（3）：CT平掃顯示顳葉出血性梗塞（紅箭）。*注意因血栓導(dǎo)致的左側(cè)橫竇高密度（藍箭）。Twocasesofemptydeltasignduetothrombosisofthesuperiorsagittalsinus.Emptydeltasign（1）TheemptydeltasignisafindingthatisseenonacontrastenhancedCT(CECT)andwasfirstdescribedinthrombosisofthesuperiorsagittalsinus.

Thesignconsistsofatriangularareaofenhancementwitharelativelylow-attenuatingcenter,whichisthethrombosedsinus.

Thelikelyexplanationisenhancementoftherichduralvenouscollateralcirculationsurroundingthethrombosedsinus,producingthecentralregionoflowattenuation.

Inearlythrombosistheemptydeltasignmaybeabsentandyouwillhavetorelyonnon-visualizationofthethrombosedveinontheCECT.

Thesignmaybeabsentaftertwomonthsduetorecanalizationwithinthethrombus.

空三角征（1）：*空三角征是增強CT檢查的表現(xiàn)，用來描述上矢狀竇栓塞。*該征由強化的三角組成，其中心為相對低的密度，竇內(nèi)的血栓所致。*硬膜竇周邊的對比強化是血栓周圍的靜脈血流。*靜脈竇血栓早期，CT增強掃描上，該空三角征可能缺乏，以至于出現(xiàn)增強CT為假陰性。*治療再通后2個月左右，該征像消失。Emptydeltasign(2)

Ontheleftacaseofthrombosisoftherighttransversesinusandthelefttransverseandsigmoidsinus(arrows).

Thereisenhancementsurroundingthethrombosedhypoattenuatingveins.

空三角征（2）：*左圖一例右側(cè)橫竇、左側(cè)橫竇及乙

狀竇栓塞的病例（箭）。*栓塞的靜脈竇呈低密度并周圍強化。VenousthrombosiswithabsenceofnormalflowvoidonT2-weightedimage..

AbsenceofnormalflowvoidonMR（1）Onspin-echoimagespatentcerebralveinsusuallywilldemonstratelowsignalintensityduetoflowvoid.

FlowvoidsarebestseenonT2-weightedandFLAIRimages,butcansometimesalsobeseenonT1-weightedimages.

Athrombuswillmanifestasabsenceofflowvoid.

Althoughthisisnotacompletelyreliablesign,itisoftenoneofthefirstthings,thatmakeyouthinkofthepossibilityofvenousthrombosis.

Thenextstephastobeacontrastenhancedstudy.OntheleftaT2-weightedimagewithnormalflowvoidintherightsigmoidsinusandjugularvein(bluearrow).

Ontheleftthereisabnormalhighsignalasaresultofthrombosis(redarrow).正常MR流空消失（1）*自旋回撥成像，由于流空而使得靜脈竇呈低信號。

最宜顯示“流空征”是T2WI或FLAIR，有時T1WI

也能看到。*當(dāng)靜脈竇血栓時，血“流空征”消失，盡管它不是完全可靠的征象，也是首先值得注意的表現(xiàn)

，由此應(yīng)想到靜脈竇血栓的可能。*接下來必須做MR增強掃描。*左圖T2WI右側(cè)乙狀竇及頸靜脈（藍箭）表現(xiàn)正常的血“流空征”，而左側(cè)的乙狀竇則由于靜

脈竇栓塞而形成不正常的高信號。AbsenceofnormalflowvoidonMR(2)

TheimagesontheleftshowabnormalhighsignalontheT1-weightedimagesduetothrombosis.

Thethrombosisextendsfromthedeepcerebralveinsandstraightsinustothetransverseandsigmoidsinusontheright.Noticethenormalflowvoidinthelefttransversesinusontherightlowerimage.AbsenceofnormalflowvoidonMR-imagescanbeveryhelpfulindetectingvenousthrombosis,buttherearesomepitfallsaswewilldiscusslater.

SlowflowcanoccurinveinsandcauseT1hyperintensity.VenousthrombosiswithabsenceofnormalflowvoidonT1-weightedimage.正常MR流空消失（2）*左圖顯示由于靜脈栓塞而導(dǎo)致的T1WI異常信號血栓由右側(cè)乙狀竇、橫竇、直竇并延

伸至大腦的深靜脈。*注意右下圖上左側(cè)橫竇的正?！傲骺照鳌?。*在搜尋靜脈竇栓塞中，MR上正常流空征的缺失，是非常有用的征象。但卻有陷

阱（后續(xù)討論）*當(dāng)靜脈內(nèi)血流緩慢時，可引起T1WI高信號。Venousinfarction(1)Theothersignthatcanhelpyouinmakingthediagnosisofunsuspectedvenousthrombosisisvenousinfarction.

Venousthrombosisleadstoahighvenouspressurewhichfirstresultsinvasogenicedemainthewhitematteroftheaffectedarea.

Whentheprocescontinuesitmayleadtoinfarctionanddevelopmentofcytotoxicedemanexttothevasogenicedema.

Thisisunlikeinanarterialinfarctioninwhichthereisonlycytotoxicedemaandnovasogenicedema.

Duetothehighvenouspressurehemorrhageisseenmorefrequentlyinvenousinfarctioncomparedtoarterialinfarction.Sincewearenotthatfamiliarwithvenousinfarctions,weoftenthinkofthemasinfarctionsinanatypicallocationorinanon-arterialdistribution.venousinfarctionsdohaveatypicaldistribution靜脈性腦梗塞（1）*另一個能幫你從容診斷腦靜脈血栓形成的可靠征象是靜脈性腦梗塞。*腦靜脈血栓形成導(dǎo)致腦靜脈高壓并致使受累區(qū)的腦白質(zhì)早期出現(xiàn)血管源性水腫。*在當(dāng)病情繼續(xù)進展，緊隨著血管源性水腫而導(dǎo)致腦梗塞和細胞毒性水腫之進展。*這與動脈性腦梗塞僅細胞毒性水腫而沒有血管源性水腫的病理變化截然不同。*與動脈性腦梗塞比較，由高靜脈壓而導(dǎo)致

的出血在靜脈性腦梗塞中更多見。*

正是因為不熟悉靜脈性腦梗塞，因此，當(dāng)

發(fā)現(xiàn)腦梗塞位于非動脈性梗塞的好發(fā)部位

或為非動脈分布區(qū)的梗塞時，應(yīng)該想到本病。大腦內(nèi)靜脈血栓上矢狀竇血栓Labbe靜脈血栓靜脈性腦梗塞有典型分布區(qū)Sincemanyveinsaremidlinestructures,venousinfarctsareoftenbilateral.

Thisisseeninthrombosisofthesuperiorsagittalsinus,straightsinusandtheinternalcerebralveins.Venousinfarction(2)-Superiorsagittalsinusthrombosis

Themostfrequentlythrombosedvenousstructureisthesuperiorsagittalsinus.

Infarctionisseenin75%ofcases.

Theabnormalitiesareparasagittalandfrequentlybilateral.

Hemorrhageisseenin60%ofthecases.Ontheleftbilateralparasagittaledemaandsubtehemorrhageinapatientwiththrombosisofthesuperiorsagittalsinus.Bilateralinfarctioninsuperiorsagittalsinusthrombosisvenousinfarctsareoftenbilateralinthemidlineandhemorrhagic靜脈性腦梗塞常常在中線的雙側(cè)并伴有出血上矢狀竇栓塞伴中線兩側(cè)靜脈性腦梗塞由于許多靜脈是中線結(jié)構(gòu)，靜脈性腦梗塞常是雙側(cè)。該特征見于上矢狀竇、直竇以及大腦內(nèi)靜脈栓塞。靜脈性腦梗塞（2）-上矢狀竇栓塞*上矢狀竇是最頻繁形成靜脈栓塞的結(jié)構(gòu)。*75%的病例出現(xiàn)靜脈性腦梗塞。*伴隨的異常表現(xiàn)出現(xiàn)在矢狀竇旁，多是雙側(cè)性。*這與動脈性腦梗塞僅細胞毒性水腫而沒有血管源性水腫的病理變化截然不同。*60%的病例伴出血。*

左圖即是上矢狀竇血栓伴雙側(cè)矢旁水腫及少許出血。OntheleftreconstructedsagittalCT-imagesinapatientwithbilateralparasagittalhemorrhageduetothrombosisofthesuperiorsagittalsinus.

Theredarrowonthecontrastenhancedimageindicatesthefillingdefectcausedbythethrombus.Venousinfarcts(3)-veinofLabbe

AnothertypicalvenousinfarctionisduetothrombosisoftheveinofLabbe.

Ontheleftimagesdemonstratinghypodensityinthewhitematterandlesspronouncedinthegraymatterofthelefttemporallobe.

Thereisabroaddifferentialdiagnosisincludingarterialinfarction,infection,tumoretc.

Noticethatthereissomelineardensitywithintheinfarctedarea.

Thisisduetohemorrhage.

InthedifferentialdiagnosiswealsoshouldincludeavenousinfarctintheterritoryoftheveinofLabbe.

Thesubtledensityintheareaofthelefttransversesinus(arrow)isthekeytothediagnosis.

ThisisadirectsignofthrombosisandthenextstepisaCECT,whichconfirmedthediagnosis(notshown打藥的CT圖未提供).VenousinfarctinLabbeterritoryLabbe靜脈分布區(qū)靜脈性腦梗塞左圖矢狀CT重組圖顯示：上矢狀竇血栓形成而導(dǎo)致的雙側(cè)矢旁腦實質(zhì)出血。增強掃描圖中紅箭顯示的為由血栓造成的上矢狀竇的充盈缺損。靜脈性腦梗塞（3）-Labbe靜脈另一例典型的靜脈性腦梗塞：源自Labbe靜脈栓塞。左圖示左側(cè)顳葉灰質(zhì)及白質(zhì)密度明顯減低區(qū)，這里需要鑒別的疾病很多，包括動脈性腦梗塞，感染，腫瘤等。注意：在梗塞區(qū)有一些線樣高密度，是出血所致。鑒別診斷中當(dāng)然也包括Labbe靜脈分布區(qū)的靜脈性梗塞。在左側(cè)橫竇（箭）區(qū)域的少許高密度影則是診斷的關(guān)鍵。這是血栓形成的一個直接征象，接下來就是做增強CT證實（打藥的CT未提供）Ontheleftimagesofapatientwithhemorrhageinthetemporallobe.

Whenthehemorrhagiccomponentoftheinfarctionislarge,itmaylooklikeanyotherintracerebralhematomawithsurroundingvasogenicedema.

Thecluetothediagnosisinthiscaseisseenonthecontrastenhancedimage,whichnicelydemonstratesthefillingdefectinthesigmoidsinus(bluearrow).HemorrhagicvenousinfarctinLabbeterritoryOntheleftasimilarcaseonMR.

Thereisacombinationofvasogenicedema(redarrow),cytotoxicedemaandhemorrhage(bluearrow).

Thesefindingsandthelocationinthetemporallobe,shouldmakeyouthinkofvenousinfarctionduetothrombosisoftheveinofLabbe.

ThenextexaminationshouldbeacontrastenhancedMRorCTtoprovethediagnosis.HemorrhagicvenousinfarctinLabbeterritoryLabbe靜脈分布區(qū)出血性靜脈性腦梗塞Labbe靜脈分布區(qū)出血性靜脈性腦梗塞左圖：左側(cè)顳葉出血左圖：當(dāng)梗塞區(qū)出血成分較大時，看似像其他的腦內(nèi)出血并環(huán)繞血管源性水腫。該病例的診斷線索是增強CT的所見，即乙狀竇內(nèi)的充盈缺損（藍箭，對側(cè)比較），它是最好的證據(jù)。左圖：另一個類似病例的MR*這例表現(xiàn)：血管源性水腫（紅箭）與細胞毒性水腫及出血（藍箭）的綜合影。*這些表現(xiàn)和顳葉的病變定位應(yīng)使我們想到Labbe靜脈血栓形成導(dǎo)致的靜脈性腦梗塞。*接下來的檢查應(yīng)該是MRI或CT的增強掃描，從而證實該診斷。Venousinfarction(4)-Deepcerebralveins

OnthefarleftaFLAIRimagedemonstratinghighsignalintheleftthalamus.

Whenyoulookcloselyandyoumayhavetoenlargetheimagetoappreciatethis,thereisalsohighsignalinthebasalgangliaontheright.

Thesebilateralfindingsshouldraisethesuspicionofdeepcerebralvenousthrombosis.

AsagittalCTreconstructiondemonstratesafillingdefectinthestraightsinusandtheveinofGalen(arrows).Ontheleftayoungpatientwithbilateralabnormalitiesintheregionofthebasalganglia.

Basedontheimagingfindingsthereisabroaddifferentialincludingsmallvesseldisease,demyelinisation,intoxicationandmetabolicdisorders.

ContinuewiththeT1-weightedimagesinthispatient.接下來看T1WI圖靜脈性腦梗塞（4）-腦深靜脈*左上FLAIR圖證實左側(cè)丘腦高信號。*當(dāng)仔細觀察發(fā)現(xiàn)右側(cè)底節(jié)區(qū)也有高信號。*這種雙側(cè)性異常應(yīng)高度懷疑腦深部靜脈的血栓形成。*矢狀CT重建圖證實直竇、Galen靜脈（箭）內(nèi)的充盈缺損。*左圖一個年輕病人，雙側(cè)基底節(jié)區(qū)的異常。*基于這種影像的表現(xiàn)，需要鑒別的疾病包括：小血管病、脫髓鞘、中毒、代謝病。*這種雙側(cè)性異常應(yīng)高度懷疑腦深部靜脈的血栓形成。*矢狀CT重建圖證實直竇、Galen靜脈（箭）內(nèi)的充盈缺損。NoticetheabnormalhighsignalintheinternalcerebralveinsandstraightsinusontheT1-weightedimages,wherethereshouldbealowsignalduetoflowvoid.

Thiswasunlikethelowsignalinothersinuses.

Thediagnosisisbilateralinfarctionsinthebasalgangliaduetodeepcerebralvenousthrombosis.BilateralinfarctionsinthebasalgangliaduetodeepcerebralvenousthrombosisVenousinfarction(5)-Edema

Insomecasesofvenousthrombosistheimagingfindingscanresolvecompletely.

左下圖apatientwithasubcorticalareaofhighsignalintensity.Thefirstimpressionwasthatthiscouldbealowgradeglioma.Onafollowupscantheabnormalitieshadresolvedcompletely.

Inretrospectadensevesselsignwasseeninoneofthecorticalveinsandthediagnosisofvenousthrombosiswasmade.

Thehighsignalintensitycanbeattributedtovasogenicedemaduetothehighvenouspressurethatresultedfromthethrombosis.由于腦深部靜脈血栓形成而導(dǎo)致的雙側(cè)基底節(jié)區(qū)腦梗塞。靜脈性腦梗塞（5）-水腫*在一些靜脈性血栓形成的病人中，其異常的表現(xiàn)能夠完全消失。*左下圖示一個病人的皮質(zhì)下區(qū)高信號影，低級別星形細胞瘤可能會是第一印象。但在隨后的復(fù)查

發(fā)現(xiàn)該異常影完全消失。*回顧中發(fā)現(xiàn)，皮質(zhì)靜脈的一支血管表現(xiàn)為“致密血管征”并作出靜脈血栓形成的診斷。*高信號強度歸于血管源性水腫，這是由于靜脈內(nèi)血栓形成而導(dǎo)致的腦靜脈高壓。ImaginginsuspectedthrombosisCT-venographyCT-venographyisasimpleandstraightforwardtechniquetodemonstratevenousthrombosis.

Intheearlystagethereisnon-enhancementofthethrombosedveinandinalaterstagethereisnon-enhancementofthethrombuswithsurroundingenhancementknownasemptydeltasign,asdiscussedbefore.UnlikeMR,CT-venographyvirtuallyhasnopitfalls.

Theonlythingthatyoudon‘twanttodo,istoscantooearly,i.e.beforetheveinsenhanceortoolate,i.e.whenthecontrastisgone.

SomeadvocatetodoascanlikeaCT-arteriographyandjustadd5-10secondsdelay.

Tobeonthesafesideweadvocate45-50secondsdelayafterthestartofcontrastinjection.

Weuseatleast70ccofcontrast.OntheleftsomeimagesofaCT-venographydemonstratingthrombosisinmanysinuses.疑為靜脈血栓形成病人的成像檢查CT靜脈成像CT靜脈成像作為證實靜脈血栓形成的簡單而直接的技術(shù)。在注藥早期階段，表現(xiàn)為栓塞的靜脈不強化，而在后期階段則表現(xiàn)為血栓不強化而血栓周圍環(huán)繞對比強化，即前面說的“空三角征”。與MR不同，CT靜脈成像幾乎沒有陷阱。須注意的是：不要啟動掃描太早，也就是指靜脈強化之前；或太遲，也就是指對比劑廓清時。也有提倡采取像CT動脈血管成像，但需要再延時5-10秒。為了萬無一失，我們提倡注射對比劑開始后的45-50秒。使用至少70ml的對比劑。左圖一些CT靜脈成像的圖像，這些圖證實許多靜脈竇內(nèi)血栓形成。apatientwithaninfarctionintheareaoftheveinofLabbe.

Onthenon-enhancedimagesyoucanappreciatethedensethrombuswithinthetransversesinusandthehemorrhageintheinfarctedarea.

Ontheenhancedimagesafillingdefectcanbeseeninthetransversesinus.靜脈竇血栓伴梗塞及出血注：精細的影像學(xué)評價：CT的平掃與增強結(jié)合*Labbe靜脈區(qū)域的梗塞*CT平掃圖你能看到橫竇內(nèi)高密度的血栓及梗塞區(qū)的出血。

在CT增強的圖像上，可見橫竇內(nèi)的明確的充盈缺損。MR-venographyTheMR-techniquesthatareusedforthediagnosisofcerebralvenousthrombosisare:

Time-of-flight(TOF),phase-contrastangiography(PCA)andcontrast-enhancedMR-venography:

Time-of-Flightangiographyisbasedonthephenomenonofflow-relatedenhancementofspinsenteringintoanimagingslice.

Asaresultofbeingunsaturated,thesespinsgivemoresignalthatsurroundingsaturatedspins.

Phase-contrastangiographyusestheprinciplethatspinsinbloodthatismovinginthesamedirectionasamagneticfieldgradientdevelopaphaseshiftthatisproportionaltothevelocityofthespins.

Thisinformationcanbeusedtodeterminethevelocityofthespins.Thisimagecanbesubtractedfromtheimage,thatisacquiredwithoutthevelocityencodinggradients,toobtainanangiogram.

Contrast-enhancedMR-venographyusestheT1-shorteningofGadolinium.

Itissimilartocontrast-enhancedCT-venography.

WhenyouuseMIP-projections,alwayslookatthesourceimages.TransverseMIPimageofaPhase-Contrastangiography.Therighttransversesinusandjugularveinhavenosignalduetothrombosis.

相位對比MRA橫向的MIP示右側(cè)橫竇和頸靜脈由于血栓形成導(dǎo)致的信號缺失MR靜脈血管成像用于診斷腦靜脈血栓形成的MR技術(shù)有：TOF法，PCA法以及對比增強靜脈血管成像。時間飛躍法血管成像：是基于進入成像層面的氫質(zhì)子自旋流入增強的現(xiàn)象，使進入層面而未被飽和的氫質(zhì)子獲得更高的信號，而與其周圍被飽和的靜止組織的自旋質(zhì)子（無信號）形成對比。

相位對比法血管成像：*是利用血液內(nèi)自旋氫質(zhì)子群隨施加的梯度磁場而按同一方向流動之原理，進而按照自旋質(zhì)子群流速的比例產(chǎn)生相位變化。*這些信息可用于確定自旋質(zhì)子群的流速。*通過圖像的減影（去除背景靜止組織，僅留下血流造成的相位變化信息）、重建從而獲得血管圖像。對比增強法MR靜脈血管成像：是利用能縮短T1馳豫的Gadolinium這種對比劑成像。與CT增強血管成像相似。當(dāng)使用MIP投影圖時一定要注意瀏覽影像的原始圖即源圖。OntheleftalateralandobliqueMIPimagefromanormalcontrast-enhancedMRvenography.

NoticetheprominentveinofTrolard(redarrow)andveinofLabbe(bluearrow).

EveryMRtechniqueshasitsownpitfallsaswewilldiscussinamoment.

Contrast-enhancedMRvenographyhasthedisadvantagethatyouneedtogivecontrast,buthaslesspitfalls.對比劑增強MR靜脈竇成像左圖正常的增強MR靜脈竇成像（側(cè)、斜MIP圖）注意：圖中展示的Trolard靜脈（紅箭）和Labbe（藍箭）每種MR技術(shù)都有其本身的陷阱（即刻討論的內(nèi)容）每種MR技術(shù)都有其本身的陷阱（即刻討論的內(nèi)容）增強MR靜脈成像，其缺點即需要使用造影劑，但少有誤區(qū)。DSAAngiographyisonlyperformedinseverecases,whenaninterventionisplanned.Imagesofapatientwithvenousthrombosis,whowasunconsiousanddidnotrespondtoanticoagulanttherapy.

Thereisthrombosisofthesuperiorsagittalsinus(redarrow),straightsinus(bluearrow)andtransverseandsigmoidsinus(yellowarrow).Continuewiththevideoofthethrombectomy.視頻：靜脈竇取栓術(shù)DSA及經(jīng)皮血栓清除術(shù)鼠標放到這里，點擊觀看視頻播放*

DSA血管造影只是用于嚴重患者，而后制定介入治療計劃。*

上圖為靜脈栓塞的影像，該病人意識喪失，對抗凝治療無效果。*

上矢狀竇（紅箭），直竇（藍箭）及橫竇和乙狀竇（黃箭）血栓。*

靜脈取栓術(shù)視頻ArachnoidGranulationsArachnoidgranulationsaresmallprotrusionsofthearachnoidthroughtheduramater.

Theyprotrudeintothevenoussinusesandmaymimicfillingdefectscausedbythrombus.

Usuallythesegranulationsareeasilytodifferentiatefromthrombosis.PitfallsinCTCT陷阱*蛛網(wǎng)膜顆粒是指透過硬腦膜的蛛網(wǎng)膜的小起。*蛛網(wǎng)膜顆粒突入到靜脈竇內(nèi)并很像由于血栓形成的充盈缺損。*一般而言，這樣的蛛網(wǎng)膜顆粒容易與血栓鑒別。蛛網(wǎng)膜顆粒蛛網(wǎng)膜突入到硬腦膜靜脈竇內(nèi)形成的絨毛狀或顆粒狀突起,腦脊液經(jīng)此滲入硬腦膜竇內(nèi)，回流入靜脈。附：說說蛛網(wǎng)膜顆粒A

正位片：頂前區(qū)、中線旁低密度骨缺損，圓

形或卵圓形，邊界清。B

側(cè)位片或切線位：呈弧形隆起，顱板變薄

，嚴重者內(nèi)外板和板障分辨不清，僅呈一致密的弧線。X線表現(xiàn)Digitalsubtractionangiogram,internalcarotidarteryinjection,venousphase,showingprominentarachnoidgranulationintheproximalthirdoftherighttransversesinus(arrow).Angiogramshowsthesuperiorsagittalsinus(arrow)dividinginto3separatechannelsthatflowaroundthefillingdefectandreconstitutedistally.DSA（頸內(nèi)動脈注射，靜脈期）圖顯示右側(cè)橫竇的近側(cè)1/3處突入的蛛網(wǎng)膜顆粒（箭）血管造影顯示被分隔為三路的上矢狀竇（箭），其各自的血流周圍的充盈缺損，至其遠側(cè)而再匯合。DSA所見CT表現(xiàn)平掃：低密度或等密度（與竇內(nèi)血液比）增強后延遲掃描：突入竇內(nèi)的局限性充盈缺損MR表現(xiàn)MRI比CT更易發(fā)現(xiàn)和確定蛛網(wǎng)膜粒，為突入竇腔內(nèi)局限且邊緣清晰的非血流異常信號：T1WI：多數(shù)為低信號，少數(shù)為等信號。T2WI：均勻或不均勻高信號。增強掃描：局限性充盈缺損。部分蛛網(wǎng)膜顆粒中，可有點條狀顯著強化，其原因可能是其內(nèi)的結(jié)締組織成分的作用。多數(shù)蛛網(wǎng)膜顆粒位于淺表靜脈匯入靜脈竇處，部分蛛網(wǎng)膜顆粒中有一條到幾條靜脈直接進入。圖7右橫竇蛛網(wǎng)膜顆粒內(nèi)見靜脈直接進入。圖8VR表淺靜脈成像見蛛網(wǎng)膜顆粒位于淺靜脈匯入橫竇處（白箭示蛛網(wǎng)膜顆粒，黑箭示下吻合靜脈）MR靜脈竇成像（右圖）：突入竇腔的局限性壓跡，其周圍仍為血流信號CT靜脈竇成像鑒別診斷

血栓通常累及長段竇腔或多個竇受累，并可延伸入皮層靜脈CT值不同MRI上不同序列信號不同梗阻以遠的靜脈竇血流異常

常位于淺表靜脈匯入靜脈竇處,其內(nèi)見靜脈進入為特征性表現(xiàn)邊界光滑,偶見不規(guī)則也可分辨其為多個小蛛網(wǎng)膜顆粒融和CT值接近腦脊液密度,偶爾見鈣化橫竇內(nèi)蛛網(wǎng)膜顆粒可多發(fā)蛛網(wǎng)膜顆粒的近段和遠段靜脈竇內(nèi)血流都是正常的蛛網(wǎng)膜顆粒腦靜脈竇栓塞MimickofdenseclotsignNormallyveinsareslightlydenserthanbraintissueandinsomecasesitisdifficulttosaywhetheritisnormalortoodense.

Inthesecasesacontrastenhancedscanisnecessarytosolvethisproblem.

Ontheleftanimageofathrombosedtransversesinusandnexttoitanormaltransversesinus.Normaltransversesinus(left)andthrombosedtransversesinus(right).正常橫竇（左圖）和栓塞的橫竇（右圖）致密凝塊征的假象正常的腦靜脈密度要比腦組織有輕度的增高，有的病例很難說清楚是正常還是病理性的增高。因此，在一些病例需要增強掃描予以解決。左圖：一幅是栓塞的橫竇，另一幅是正常的橫竇。HematomamimickingadenseclotsignHematomasimulatingdenseclotsign.

Usuallythereisnoproblemindifferentiatingahematomafromathrombosedsinus.

Hereapatientwithaperipheralintracerebralhematoma.

Becauseitislocatedintheareaofthetransversesinusitsimulatesathrombosedtransversesinus.Ininfantsthebrainisusuallylessdensethaninolderchildrenandadults.

Thisresultsinarelativehighdensityofthebloodinthesagittalsinuscomparedtothebrain,whichsimulatesadenseclotsign.Mimickofdenseclotsigninaninfant嬰兒“致密凝塊征”之假象這種假象的成因？嬰兒腦的密度通常較大齡兒童或成人的腦的密度低，其結(jié)果相對高密度的上矢狀竇的血液與腦相對照，而形成酷似“致密凝塊征”?？崴啤爸旅苣龎K征”的血腫酷似“致密凝塊征”的血腫一般來說，血腫與栓塞的靜脈竇鑒別不困難。這是一例外圍性的腦內(nèi)血腫，由于位于橫竇的區(qū)域，故而酷似栓塞的橫竇。WrongbolustimingOntheleftthreeimagesofapatientwithvenousthrombosisinthesuperiorsagittalsinus.

OnthefarleftweseeadensevesselsignontheunenhancedCT.

Inthemiddleanimagemade25secondsafterthestartofthecontrastinjection.Thereisarterialenhancementanditlooksasifthesuperiorsagittalsinusenhances,butinfactwhatweseeistheshinethroughofthedensethrombus.

Onlyontheimageontheright,whichwasmade45secondsaftercontrastinjectionthereisanemptydeltasign,whichprovesthepresenceofathrombusinthesinus.PseudoemptydeltasignHereapatientwithasubduralhematomaontheleftside,thathasspreadtotheregionofthesuperiorsagittalsinus(arrows).

Atfirstimpressionthislookslikeanemptydeltasign.Byscrollingthroughthedataset,itwasobviousthatitwasanextentionofthehematoma.

Ahyperdenseempyemacansometimesalsomimickanemptydeltasign.左側(cè)硬膜下血腫已經(jīng)蔓延至上矢狀竇區(qū)（箭）。第一印象，看似“空三角征”。連續(xù)的系列層面卻是明顯的血腫的延續(xù)。假性“空三角征”表現(xiàn)為高密度的積膿時，也有時酷似“空三角征”。一例病人，見左側(cè)三幅圖，上矢狀竇內(nèi)靜脈血栓形成。*最左側(cè)平掃CT圖可見一個“致密血管征”。*中間的圖是注射對比劑25秒的CT圖像,動脈期的強化并似乎可見上矢狀竇強化，實際上這是致密的血栓而形成的高密度。*只有在右側(cè)的一幅圖，即注射對比劑45秒的CT圖，顯示“空三角征”，證明靜脈竇內(nèi)的血栓。不適當(dāng)?shù)脑煊皠﹫F注啟動時間OntheleftatransverseMIPofphase-contrastimages.

Todifferentiatewhetherthereisahypoplastictransversesinusorthrombosedsinus,youneedtolookatthesourceimages.

Onthesourceimageontherightyoucanseethatthereisnohypoplasia(bluearrow).

Inthiscasetherethrombosisofthelefttransversesinus.HypoplastictransversesinusHypoplasiaandaplasiaoftherightorlefttransversesinusisacommonfinding.

Itcaneasilybemistakenforsinusthrombosis,becauseontheMRAoneofthetransversesinusesismissing.

Whenyoususpect,thatthereisahypoplastictransversesinus,thenyoushouldlookatthesizeofthejugularforamen.

Ontheleftimagesofapatientwithhypoplasiaofthelefttransversesinus.

Noticethesizedifferenceofthejugularforamen.PitfallsinMRIMRI陷阱橫竇發(fā)育不良右側(cè)或左側(cè)橫竇的發(fā)育不良或不發(fā)育是一個常見的表現(xiàn).它在MRA上表現(xiàn)為一側(cè)橫竇的缺失，從而容易誤為竇栓塞。當(dāng)懷疑一側(cè)橫竇發(fā)育不良時，應(yīng)該注意觀察該側(cè)頸靜脈孔的大小。左側(cè)圖病人左側(cè)橫竇發(fā)育不良。注意：左側(cè)頸靜脈孔與右側(cè)的差異。*該病例是左側(cè)橫竇的血栓形成。*左圖：相位對比的橫向的MIP。*為了鑒別左側(cè)橫竇或乙狀竇發(fā)育不良，需要看源圖。*其右側(cè)是源圖，示左側(cè)的靜脈竇并不是發(fā)育不良（藍箭）LowsignalintensityinthrombusNormallywhenthereislowsignalinavein,itisattributedtoflowvoidandasignofpatencyofthevein.

Howeveratsomestageofthethrombusthereisintracellulardeoxyhemoglobin,whichisdarkonT2andmimicsflowvoid.

Ontheleftthereisathrombosedrighttransversesinus.

ThesinushasalowsignalintensityontheT2asaresultoftheintracellulardeoxyhemoglobin.

OnthecontrastenhancedT1itisobviousthatthesinusisfilledwiththrombus.ThrombusinrighttransversesinusisdarkonT2duetointracellulardeoxyhemoglobin(Courtesydr.HowardRowley)Ontheleftanothercasethatdemonstratesthatyoucannotfullyrelyonphasecontrastimaging.

Thesignalintheveindependsonthevelocityoftheflowingbloodandthevelocityencodingbythetechnician.

Onthefarleftapatientwithnonvisualizationofthelefttransversesinus.

Thiscouldbehypoplasia,venousthrombosisorslowflow.

OnthecontrastenhancedT1itisobviousthatthesinusfillswithcontrastandispatent.左圖：另一被證實不能充分依賴相位對比MR成像的示例靜脈的信號強度依賴于血流速度和掃描技師設(shè)置的流速編碼(venc)（附：慢血流的venc選擇10cm/s）。由于細胞內(nèi)的脫氧血紅蛋白而導(dǎo)致右側(cè)橫竇內(nèi)血栓在T2WI上是黑的。竇內(nèi)血栓呈低信號正常時，靜脈竇由于血流空效應(yīng)而表現(xiàn)為低信號，并作為靜脈通暢的標志。在對比增強T1WI上，顯然是橫竇充盈對比劑，無可非議。這可能是橫竇發(fā)育不良，靜脈血栓形成或慢血流。更靠左邊圖：左側(cè)橫竇不顯示。*對比增強掃描T1WI，明確看到橫竇內(nèi)為血栓所充填（藍箭）。*右側(cè)橫竇血栓形成，在T2WI圖像上，由于細胞內(nèi)脫氧血紅蛋白而表現(xiàn)為低信號（紅箭）。然而，血栓的某些階段，由于細胞內(nèi)的脫氧血紅蛋白而導(dǎo)致T2WI低信號，酷似血流空。*左圖：栓塞的右側(cè)橫竇。PitfallsinTOFimagingare:Signallossduetoin-planeflow.FlowsimulatedbyT1-shinethroughofmethemoglobin

withinthrombus.Onthephasecontrastimagesitisobviousthatthetransversesinusispatent.WecanconcludethatMRIhasmanyfalsepositivesandnegativesinthediagnosisofvenousthrombosis.ContrastenhancedMR-venographyisthemostreliableMRtechnique.CT-venographyisevenmorereliable,becauseitiseasyandlesssensitivetopitfalls.Flowvoidoncontrast-enhancedMROnthecontrastenhancedT1imagesontheleftthereisanareaoflowsignalintensitywithintheenhancingtransversesinus.

Thiscouldeasilybeenmistakenforacentralthrombuswithinthesinus.

Thishoweveristheresultofflowvoid.MR增強掃描上的“流空征”左側(cè)MR增強掃描圖上，強化的橫竇內(nèi)有低信號區(qū)，這會容易誤判為竇內(nèi)中心性血栓。MR的時間飛躍法（TOF）靜脈成像的陷阱是：*由于層面內(nèi)血流信號丟失（低信號）*由于血栓內(nèi)的高鐵血紅蛋白的T1投過效應(yīng)而形成的模擬血流（附：2D靜脈竇血流成像：血栓本應(yīng)黑

，但卻呈白的，形成假血流）。在相位對比成像上，它顯然是橫竇無疑。因此認為，在診斷靜脈血栓形成方面，MRI有許多的假陽性和假陰性。而對比增強MR靜脈成像是最可靠的MR技術(shù)。CT靜脈成像甚至是更可靠，不僅容易而且少有陷阱。然而，這是“流空”所導(dǎo)致的結(jié)果。ChronicduralsinusthrombosisandrelatedsyndromesDAVF（硬膜動靜脈瘺）ChronicduralsinusthrombosiscanleadtoduralarteriovenousfistulaformationandtoincreasedCSFpressure.ADAVForduralarteriovenousfistulaisanabnormalconnectionbetweenduralarteries,whicharebranchesoftheexternalcarotidwiththevenoussinuses.