脑静脉血栓形成影像学

CerebralVenousThrombosis

BarbaraSimons,GeertLycklamaaNijeholtandRobinSmithuis

RadiologydepartmentoftheMedicalCentreHaaglandenintheHagueandtheRijnlandhospitalinLeiderdorp,theNetherlands脑静脉性栓塞形成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.此时应想到静脉栓塞可能致密斑块征空三角征MR上正常流空征消失静脉性脑梗塞疑似此病的成像方法CT静脉成像MR静脉成像DSACT陷阱蛛网膜颗粒酷似致密凝块征假性空三角征错误的团注时间MRI陷阱横窦发育不良血栓内低信号强度MR对比增强时的流空硬膜窦栓塞临床与相关综合征DAWF（硬膜动静脉瘘）栓塞和脑脊液压力增高静脉分布图静脉性脑梗塞是中风的重要原因，尤其是在儿童或年轻人。它比以前更常见而且常常在最初的成像中漏诊由于临床上缺少特征而且影像所见微妙，因而诊断困难这里主要讨论的内容：*提示可疑静脉性脑梗塞的常规影像学表现*疑为静脉性脑梗塞如何进一步进行影像学检查*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.重要的解剖与临床脑静脉性栓塞多位于以下的静脉结构*主要静脉窦：上矢状窦、横窦、直窦和乙状窦。*皮质静脉：Labbe静脉，颞叶的引流静脉；Trolard静脉，为最大的皮质静脉，汇入上矢状窦。*深静脉：大脑内静脉和丘脑纹状体静脉。*海绵窦。*临床上，脑静脉栓塞可有多种症状，严重病例如头痛、癫痫、昏迷。*新生儿休克或脱水是脑静脉栓塞常见的原因。*在儿童，局灶性的感染如中耳炎或凝血障碍。*成人中，70%的病因为凝血障碍；10%源自感染女性，口服避孕药与妊娠也是其危险因素。WhentothinkofvenousthrombosisOnaroutinenon-enhancedMRorCTyoushouldthinkofthepossibilityofvenousthrombosiswhenyousee:DirectsignsofathrombusInfarctioninanon-arteriallocation,especiallyifitisbilateralandhemorrhagicCorticalorperipherallobarhemorrhageCorticaledemaVenousthrombosishasanonspecificpresentationandthereforeitisimportanttorecognizesubtleimagingfindingsandindirectsignsthatmayindicatethepresenceofthrombosis.Althoughthesefindingsareoftenpresentoninitialscans,theyarefrequentlydetectedonlyinretrospect.

Clinicallypatientswithvenousthrombosisoftenpresentwithseizures,whichisnotasymptominpatientswithanarterialinfarction.什么情况下考虑静脉窦栓塞呢？？在常规的CT或MR平扫图像若有下面的表现应该想到静脉性脑栓塞可能：*静脉血栓的直接征象*脑梗塞非动脉性的常见部位，尤其是为双侧性、出血性*皮质或周围脑叶的出血*脑皮质水肿脑静脉血栓形成为非特异性的表现，因此，认识这些微妙的影像学的表现以及间接征象很重要，它可以指出血栓形成之存在。静脉血栓形成的病人在临床上常表现癫痫，但这不是动脉性脑梗塞病人出现的症状。尽管这些表现经常地出现在最初的扫描中，但却经常只是在回顾中发现这些异常。11、透明隔静脉12、丘脑纹状体静脉13、大脑内静脉14、大脑大静脉15、基底静脉24、直窦25、蝶顶窦26、海绵窦27、海绵间窦29、岩上窦30、岩下窦1、上矢状窦2、下矢状窦3、窦汇4、横窦5、乙状窦6、颈静脉球7、颈内静脉8、浅表皮层静脉9、静脉10、大脑中浅静脉Trolard静脉Labbe静脉Rosenthal基底静脉附加：正常解剖图与静脉栓塞的病理解剖示意图正常脑静脉窦示意图上矢状窦及脑静脉栓塞伴发的脑肿胀及损伤损伤的脑组织出血Denseclotsign（1）DirectvisualizationofaclotinthecerebralveinsonanonenhancedCTscanisknownasthedenseclotsign.

Itisseeninonlyonethirdofcases.

Normallyveinsareslightlydenserthanbraintissueandinsomecasesitisdifficulttosaywhethertheveinisnormalortoodense(seepitfalls).

Inthesecasesacontrastenhancedscanisnecessarytosolvethisproblem.*致密凝块征（1）：CT平扫见到的脑静脉血栓的直接表现，出现率为1/3.*正常的脑静脉表现为密度较脑组织轻度高，但有些病例的正常与否判断确有困难（参见陷阱）。*CT增强扫描可准确地解决该问题。Denseclotsign(2)

Visualizationofathrombosedcorticalveinthatisseenasalinearorcord-likedensity,isalsoknownasthecordsign.

Anothertermthatisfrequentlyused,isthedensevesselsign.Denseclotsign(3)

Ontheleftimagesofapatientwithahemorrhagicinfarctioninthetemporallobe(redarrow).

Noticethedensetransversesinusduetothrombosis(bluearrows).*致密凝块征（2）：CT平扫见到的脑皮质静脉血栓的表现，呈线样或绳索样高密度影，即所谓绳索征（上图

红箭）。也有称其为致密血管征。*致密凝块征（3）：CT平扫显示颞叶出血性梗塞（红箭）。*注意因血栓导致的左侧横窦高密度（蓝箭）。Twocasesofemptydeltasignduetothrombosisofthesuperiorsagittalsinus.Emptydeltasign（1）TheemptydeltasignisafindingthatisseenonacontrastenhancedCT(CECT)andwasfirstdescribedinthrombosisofthesuperiorsagittalsinus.

Thesignconsistsofatriangularareaofenhancementwitharelativelylow-attenuatingcenter,whichisthethrombosedsinus.

Thelikelyexplanationisenhancementoftherichduralvenouscollateralcirculationsurroundingthethrombosedsinus,producingthecentralregionoflowattenuation.

Inearlythrombosistheemptydeltasignmaybeabsentandyouwillhavetorelyonnon-visualizationofthethrombosedveinontheCECT.

Thesignmaybeabsentaftertwomonthsduetorecanalizationwithinthethrombus.

空三角征（1）：*空三角征是增强CT检查的表现，用来描述上矢状窦栓塞。*该征由强化的三角组成，其中心为相对低的密度，窦内的血栓所致。*硬膜窦周边的对比强化是血栓周围的静脉血流。*静脉窦血栓早期，CT增强扫描上，该空三角征可能缺乏，以至于出现增强CT为假阴性。*治疗再通后2个月左右，该征像消失。Emptydeltasign(2)

Ontheleftacaseofthrombosisoftherighttransversesinusandthelefttransverseandsigmoidsinus(arrows).

Thereisenhancementsurroundingthethrombosedhypoattenuatingveins.

空三角征（2）：*左图一例右侧横窦、左侧横窦及乙

状窦栓塞的病例（箭）。*栓塞的静脉窦呈低密度并周围强化。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）*自旋回拨成像，由于流空而使得静脉窦呈低信号。

最宜显示“流空征”是T2WI或FLAIR，有时T1WI

也能看到。*当静脉窦血栓时，血“流空征”消失，尽管它不是完全可靠的征象，也是首先值得注意的表现

，由此应想到静脉窦血栓的可能。*接下来必须做MR增强扫描。*左图T2WI右侧乙状窦及颈静脉（蓝箭）表现正常的血“流空征”，而左侧的乙状窦则由于静

脉窦栓塞而形成不正常的高信号。AbsenceofnormalflowvoidonMR(2)

TheimagesontheleftshowabnormalhighsignalontheT1-weightedimagesduetothrombosis.

Thethrombosisextendsfromthedeepcerebralveinsandstraightsinustothetransverseandsigmoidsinusontheright.Noticethenormalflowvoidinthelefttransversesinusontherightlowerimage.AbsenceofnormalflowvoidonMR-imagescanbeveryhelpfulindetectingvenousthrombosis,buttherearesomepitfallsaswewilldiscusslater.

SlowflowcanoccurinveinsandcauseT1hyperintensity.VenousthrombosiswithabsenceofnormalflowvoidonT1-weightedimage.正常MR流空消失（2）*左图显示由于静脉栓塞而导致的T1WI异常信号血栓由右侧乙状窦、横窦、直窦并延

伸至大脑的深静脉。*注意右下图上左侧横窦的正常“流空征”。*在搜寻静脉窦栓塞中，MR上正常流空征的缺失，是非常有用的征象。但却有陷

阱（后续讨论）*当静脉内血流缓慢时，可引起T1WI高信号。Venousinfarction(1)Theothersignthatcanhelpyouinmakingthediagnosisofunsuspectedvenousthrombosisisvenousinfarction.

Venousthrombosisleadstoahighvenouspressurewhichfirstresultsinvasogenicedemainthewhitematteroftheaffectedarea.

Whentheprocescontinuesitmayleadtoinfarctionanddevelopmentofcytotoxicedemanexttothevasogenicedema.

Thisisunlikeinanarterialinfarctioninwhichthereisonlycytotoxicedemaandnovasogenicedema.

Duetothehighvenouspressurehemorrhageisseenmorefrequentlyinvenousinfarctioncomparedtoarterialinfarction.Sincewearenotthatfamiliarwithvenousinfarctions,weoftenthinkofthemasinfarctionsinanatypicallocationorinanon-arterialdistribution.venousinfarctionsdohaveatypicaldistribution静脉性脑梗塞（1）*另一个能帮你从容诊断脑静脉血栓形成的可靠征象是静脉性脑梗塞。*脑静脉血栓形成导致脑静脉高压并致使受累区的脑白质早期出现血管源性水肿。*在当病情继续进展，紧随着血管源性水肿而导致脑梗塞和细胞毒性水肿之进展。*这与动脉性脑梗塞仅细胞毒性水肿而没有血管源性水肿的病理变化截然不同。*与动脉性脑梗塞比较，由高静脉压而导致

的出血在静脉性脑梗塞中更多见。*

正是因为不熟悉静脉性脑梗塞，因此，当

发现脑梗塞位于非动脉性梗塞的好发部位

或为非动脉分布区的梗塞时，应该想到本病。大脑内静脉血栓上矢状窦血栓Labbe静脉血栓静脉性脑梗塞有典型分布区Sincemanyveinsaremidlinestructures,venousinfarctsareoftenbilateral.

Thisisseeninthrombosisofthesuperiorsagittalsinus,straightsinusandtheinternalcerebralveins.Venousinfarction(2)-Superiorsagittalsinusthrombosis

Themostfrequentlythrombosedvenousstructureisthesuperiorsagittalsinus.

Infarctionisseenin75%ofcases.

Theabnormalitiesareparasagittalandfrequentlybilateral.

Hemorrhageisseenin60%ofthecases.Ontheleftbilateralparasagittaledemaandsubtehemorrhageinapatientwiththrombosisofthesuperiorsagittalsinus.Bilateralinfarctioninsuperiorsagittalsinusthrombosisvenousinfarctsareoftenbilateralinthemidlineandhemorrhagic静脉性脑梗塞常常在中线的双侧并伴有出血上矢状窦栓塞伴中线两侧静脉性脑梗塞由于许多静脉是中线结构，静脉性脑梗塞常是双侧。该特征见于上矢状窦、直窦以及大脑内静脉栓塞。静脉性脑梗塞（2）-上矢状窦栓塞*上矢状窦是最频繁形成静脉栓塞的结构。*75%的病例出现静脉性脑梗塞。*伴随的异常表现出现在矢状窦旁，多是双侧性。*这与动脉性脑梗塞仅细胞毒性水肿而没有血管源性水肿的病理变化截然不同。*60%的病例伴出血。*

左图即是上矢状窦血栓伴双侧矢旁水肿及少许出血。OntheleftreconstructedsagittalCT-imagesinapatientwithbilateralparasagittalhemorrhageduetothrombosisofthesuperiorsagittalsinus.

Theredarrowonthecontrastenhancedimageindicatesthefillingdefectcausedbythethrombus.Venousinfarcts(3)-veinofLabbe

AnothertypicalvenousinfarctionisduetothrombosisoftheveinofLabbe.

Ontheleftimagesdemonstratinghypodensityinthewhitematterandlesspronouncedinthegraymatterofthelefttemporallobe.

Thereisabroaddifferentialdiagnosisincludingarterialinfarction,infection,tumoretc.

Noticethatthereissomelineardensitywithintheinfarctedarea.

Thisisduetohemorrhage.

InthedifferentialdiagnosiswealsoshouldincludeavenousinfarctintheterritoryoftheveinofLabbe.

Thesubtledensityintheareaofthelefttransversesinus(arrow)isthekeytothediagnosis.

ThisisadirectsignofthrombosisandthenextstepisaCECT,whichconfirmedthediagnosis(notshown打药的CT图未提供).VenousinfarctinLabbeterritoryLabbe静脉分布区静脉性脑梗塞左图矢状CT重组图显示：上矢状窦血栓形成而导致的双侧矢旁脑实质出血。增强扫描图中红箭显示的为由血栓造成的上矢状窦的充盈缺损。静脉性脑梗塞（3）-Labbe静脉另一例典型的静脉性脑梗塞：源自Labbe静脉栓塞。左图示左侧颞叶灰质及白质密度明显减低区，这里需要鉴别的疾病很多，包括动脉性脑梗塞，感染，肿瘤等。注意：在梗塞区有一些线样高密度，是出血所致。鉴别诊断中当然也包括Labbe静脉分布区的静脉性梗塞。在左侧横窦（箭）区域的少许高密度影则是诊断的关键。这是血栓形成的一个直接征象，接下来就是做增强CT证实（打药的CT未提供）Ontheleftimagesofapatientwithhemorrhageinthetemporallobe.

Whenthehemorrhagiccomponentoftheinfarctionislarge,itmaylooklikeanyotherintracerebralhematomawithsurroundingvasogenicedema.

Thecluetothediagnosisinthiscaseisseenonthecontrastenhancedimage,whichnicelydemonstratesthefillingdefectinthesigmoidsinus(bluearrow).HemorrhagicvenousinfarctinLabbeterritoryOntheleftasimilarcaseonMR.

Thereisacombinationofvasogenicedema(redarrow),cytotoxicedemaandhemorrhage(bluearrow).

Thesefindingsandthelocationinthetemporallobe,shouldmakeyouthinkofvenousinfarctionduetothrombosisoftheveinofLabbe.

ThenextexaminationshouldbeacontrastenhancedMRorCTtoprovethediagnosis.HemorrhagicvenousinfarctinLabbeterritoryLabbe静脉分布区出血性静脉性脑梗塞Labbe静脉分布区出血性静脉性脑梗塞左图：左侧颞叶出血左图：当梗塞区出血成分较大时，看似像其他的脑内出血并环绕血管源性水肿。该病例的诊断线索是增强CT的所见，即乙状窦内的充盈缺损（蓝箭，对侧比较），它是最好的证据。左图：另一个类似病例的MR*这例表现：血管源性水肿（红箭）与细胞毒性水肿及出血（蓝箭）的综合影。*这些表现和颞叶的病变定位应使我们想到Labbe静脉血栓形成导致的静脉性脑梗塞。*接下来的检查应该是MRI或CT的增强扫描，从而证实该诊断。Venousinfarction(4)-Deepcerebralveins

OnthefarleftaFLAIRimagedemonstratinghighsignalintheleftthalamus.

Whenyoulookcloselyandyoumayhavetoenlargetheimagetoappreciatethis,thereisalsohighsignalinthebasalgangliaontheright.

Thesebilateralfindingsshouldraisethesuspicionofdeepcerebralvenousthrombosis.

AsagittalCTreconstructiondemonstratesafillingdefectinthestraightsinusandtheveinofGalen(arrows).Ontheleftayoungpatientwithbilateralabnormalitiesintheregionofthebasalganglia.

Basedontheimagingfindingsthereisabroaddifferentialincludingsmallvesseldisease,demyelinisation,intoxicationandmetabolicdisorders.

ContinuewiththeT1-weightedimagesinthispatient.接下来看T1WI图静脉性脑梗塞（4）-脑深静脉*左上FLAIR图证实左侧丘脑高信号。*当仔细观察发现右侧底节区也有高信号。*这种双侧性异常应高度怀疑脑深部静脉的血栓形成。*矢状CT重建图证实直窦、Galen静脉（箭）内的充盈缺损。*左图一个年轻病人，双侧基底节区的异常。*基于这种影像的表现，需要鉴别的疾病包括：小血管病、脱髓鞘、中毒、代谢病。*这种双侧性异常应高度怀疑脑深部静脉的血栓形成。*矢状CT重建图证实直窦、Galen静脉（箭）内的充盈缺损。NoticetheabnormalhighsignalintheinternalcerebralveinsandstraightsinusontheT1-weightedimages,wherethereshouldbealowsignalduetoflowvoid.

Thiswasunlikethelowsignalinothersinuses.

Thediagnosisisbilateralinfarctionsinthebasalgangliaduetodeepcerebralvenousthrombosis.BilateralinfarctionsinthebasalgangliaduetodeepcerebralvenousthrombosisVenousinfarction(5)-Edema

Insomecasesofvenousthrombosistheimagingfindingscanresolvecompletely.

左下图apatientwithasubcorticalareaofhighsignalintensity.Thefirstimpressionwasthatthiscouldbealowgradeglioma.Onafollowupscantheabnormalitieshadresolvedcompletely.

Inretrospectadensevesselsignwasseeninoneofthecorticalveinsandthediagnosisofvenousthrombosiswasmade.

Thehighsignalintensitycanbeattributedtovasogenicedemaduetothehighvenouspressurethatresultedfromthethrombosis.由于脑深部静脉血栓形成而导致的双侧基底节区脑梗塞。静脉性脑梗塞（5）-水肿*在一些静脉性血栓形成的病人中，其异常的表现能够完全消失。*左下图示一个病人的皮质下区高信号影，低级别星形细胞瘤可能会是第一印象。但在随后的复查

发现该异常影完全消失。*回顾中发现，皮质静脉的一支血管表现为“致密血管征”并作出静脉血栓形成的诊断。*高信号强度归于血管源性水肿，这是由于静脉内血栓形成而导致的脑静脉高压。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.疑为静脉血栓形成病人的成像检查CT静脉成像CT静脉成像作为证实静脉血栓形成的简单而直接的技术。在注药早期阶段，表现为栓塞的静脉不强化，而在后期阶段则表现为血栓不强化而血栓周围环绕对比强化，即前面说的“空三角征”。与MR不同，CT静脉成像几乎没有陷阱。须注意的是：不要启动扫描太早，也就是指静脉强化之前；或太迟，也就是指对比剂廓清时。也有提倡采取像CT动脉血管成像，但需要再延时5-10秒。为了万无一失，我们提倡注射对比剂开始后的45-50秒。使用至少70ml的对比剂。左图一些CT静脉成像的图像，这些图证实许多静脉窦内血栓形成。apatientwithaninfarctionintheareaoftheveinofLabbe.

Onthenon-enhancedimagesyoucanappreciatethedensethrombuswithinthetransversesinusandthehemorrhageintheinfarctedarea.

Ontheenhancedimagesafillingdefectcanbeseeninthetransversesinus.静脉窦血栓伴梗塞及出血注：精细的影像学评价：CT的平扫与增强结合*Labbe静脉区域的梗塞*CT平扫图你能看到横窦内高密度的血栓及梗塞区的出血。

在CT增强的图像上，可见横窦内的明确的充盈缺损。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.

相位对比MRA横向的MIP示右侧横窦和颈静脉由于血栓形成导致的信号缺失MR静脉血管成像用于诊断脑静脉血栓形成的MR技术有：TOF法，PCA法以及对比增强静脉血管成像。时间飞跃法血管成像：是基于进入成像层面的氢质子自旋流入增强的现象，使进入层面而未被饱和的氢质子获得更高的信号，而与其周围被饱和的静止组织的自旋质子（无信号）形成对比。

相位对比法血管成像：*是利用血液内自旋氢质子群随施加的梯度磁场而按同一方向流动之原理，进而按照自旋质子群流速的比例产生相位变化。*这些信息可用于确定自旋质子群的流速。*通过图像的减影（去除背景静止组织，仅留下血流造成的相位变化信息）、重建从而获得血管图像。对比增强法MR静脉血管成像：是利用能缩短T1驰豫的Gadolinium这种对比剂成像。与CT增强血管成像相似。当使用MIP投影图时一定要注意浏览影像的原始图即源图。OntheleftalateralandobliqueMIPimagefromanormalcontrast-enhancedMRvenography.

NoticetheprominentveinofTrolard(redarrow)andveinofLabbe(bluearrow).

EveryMRtechniqueshasitsownpitfallsaswewilldiscussinamoment.

Contrast-enhancedMRvenographyhasthedisadvantagethatyouneedtogivecontrast,buthaslesspitfalls.对比剂增强MR静脉窦成像左图正常的增强MR静脉窦成像（侧、斜MIP图）注意：图中展示的Trolard静脉（红箭）和Labbe（蓝箭）每种MR技术都有其本身的陷阱（即刻讨论的内容）每种MR技术都有其本身的陷阱（即刻讨论的内容）增强MR静脉成像，其缺点即需要使用造影剂，但少有误区。DSAAngiographyisonlyperformedinseverecases,whenaninterventionisplanned.Imagesofapatientwithvenousthrombosis,whowasunconsiousanddidnotrespondtoanticoagulanttherapy.

Thereisthrombosisofthesuperiorsagittalsinus(redarrow),straightsinus(bluearrow)andtransverseandsigmoidsinus(yellowarrow).Continuewiththevideoofthethrombectomy.视频：静脉窦取栓术DSA及经皮血栓清除术鼠标放到这里，点击观看视频播放*

DSA血管造影只是用于严重患者，而后制定介入治疗计划。*

上图为静脉栓塞的影像，该病人意识丧失，对抗凝治疗无效果。*

上矢状窦（红箭），直窦（蓝箭）及横窦和乙状窦（黄箭）血栓。*

静脉取栓术视频ArachnoidGranulationsArachnoidgranulationsaresmallprotrusionsofthearachnoidthroughtheduramater.

Theyprotrudeintothevenoussinusesandmaymimicfillingdefectscausedbythrombus.

Usuallythesegranulationsareeasilytodifferentiatefromthrombosis.PitfallsinCTCT陷阱*蛛网膜颗粒是指透过硬脑膜的蛛网膜的小起。*蛛网膜颗粒突入到静脉窦内并很像由于血栓形成的充盈缺损。*一般而言，这样的蛛网膜颗粒容易与血栓鉴别。蛛网膜颗粒蛛网膜突入到硬脑膜静脉窦内形成的绒毛状或颗粒状突起,脑脊液经此渗入硬脑膜窦内，回流入静脉。附：说说蛛网膜颗粒A

正位片：顶前区、中线旁低密度骨缺损，圆

形或卵圆形，边界清。B

侧位片或切线位：呈弧形隆起，颅板变薄

，严重者内外板和板障分辨不清，仅呈一致密的弧线。X线表现Digitalsubtractionangiogram,internalcarotidarteryinjection,venousphase,showingprominentarachnoidgranulationintheproximalthirdoftherighttransversesinus(arrow).Angiogramshowsthesuperiorsagittalsinus(arrow)dividinginto3separatechannelsthatflowaroundthefillingdefectandreconstitutedistally.DSA（颈内动脉注射，静脉期）图显示右侧横窦的近侧1/3处突入的蛛网膜颗粒（箭）血管造影显示被分隔为三路的上矢状窦（箭），其各自的血流周围的充盈缺损，至其远侧而再汇合。DSA所见CT表现平扫：低密度或等密度（与窦内血液比）增强后延迟扫描：突入窦内的局限性充盈缺损MR表现MRI比CT更易发现和确定蛛网膜粒，为突入窦腔内局限且边缘清晰的非血流异常信号：T1WI：多数为低信号，少数为等信号。T2WI：均匀或不均匀高信号。增强扫描：局限性充盈缺损。部分蛛网膜颗粒中，可有点条状显著强化，其原因可能是其内的结缔组织成分的作用。多数蛛网膜颗粒位于浅表静脉汇入静脉窦处，部分蛛网膜颗粒中有一条到几条静脉直接进入。图7右横窦蛛网膜颗粒内见静脉直接进入。图8VR表浅静脉成像见蛛网膜颗粒位于浅静脉汇入横窦处（白箭示蛛网膜颗粒，黑箭示下吻合静脉）MR静脉窦成像（右图）：突入窦腔的局限性压迹，其周围仍为血流信号CT静脉窦成像鉴别诊断

血栓通常累及长段窦腔或多个窦受累，并可延伸入皮层静脉CT值不同MRI上不同序列信号不同梗阻以远的静脉窦血流异常

常位于浅表静脉汇入静脉窦处,其内见静脉进入为特征性表现边界光滑,偶见不规则也可分辨其为多个小蛛网膜颗粒融和CT值接近脑脊液密度,偶尔见钙化横窦内蛛网膜颗粒可多发蛛网膜颗粒的近段和远段静脉窦内血流都是正常的蛛网膜颗粒脑静脉窦栓塞MimickofdenseclotsignNormallyveinsareslightlydenserthanbraintissueandinsomecasesitisdifficulttosaywhetheritisnormalortoodense.

Inthesecasesacontrastenhancedscanisnecessarytosolvethisproblem.

Ontheleftanimageofathrombosedtransversesinusandnexttoitanormaltransversesinus.Normaltransversesinus(left)andthrombosedtransversesinus(right).正常横窦（左图）和栓塞的横窦（右图）致密凝块征的假象正常的脑静脉密度要比脑组织有轻度的增高，有的病例很难说清楚是正常还是病理性的增高。因此，在一些病例需要增强扫描予以解决。左图：一幅是栓塞的横窦，另一幅是正常的横窦。HematomamimickingadenseclotsignHematomasimulatingdenseclotsign.

Usuallythereisnoproblemindifferentiatingahematomafromathrombosedsinus.

Hereapatientwithaperipheralintracerebralhematoma.

Becauseitislocatedintheareaofthetransversesinusitsimulatesathrombosedtransversesinus.Ininfantsthebrainisusuallylessdensethaninolderchildrenandadults.

Thisresultsinarelativehighdensityofthebloodinthesagittalsinuscomparedtothebrain,whichsimulatesadenseclotsign.Mimickofdenseclotsigninaninfant婴儿“致密凝块征”之假象这种假象的成因？婴儿脑的密度通常较大龄儿童或成人的脑的密度低，其结果相对高密度的上矢状窦的血液与脑相对照，而形成酷似“致密凝块征”。酷似“致密凝块征”的血肿酷似“致密凝块征”的血肿一般来说，血肿与栓塞的静脉窦鉴别不困难。这是一例外围性的脑内血肿，由于位于横窦的区域，故而酷似栓塞的横窦。WrongbolustimingOntheleftthreeimagesofapatientwithvenousthrombosisinthesuperiorsagittalsinus.

OnthefarleftweseeadensevesselsignontheunenhancedCT.

Inthemiddleanimagemade25secondsafterthestartofthecontrastinjection.Thereisarterialenhancementanditlooksasifthesuperiorsagittalsinusenhances,butinfactwhatweseeistheshinethroughofthedensethrombus.

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

Atfirstimpressionthislookslikeanemptydeltasign.Byscrollingthroughthedataset,itwasobviousthatitwasanextentionofthehematoma.

Ahyperdenseempyemacansometimesalsomimickanemptydeltasign.左侧硬膜下血肿已经蔓延至上矢状窦区（箭）。第一印象，看似“空三角征”。连续的系列层面却是明显的血肿的延续。假性“空三角征”表现为高密度的积脓时，也有时酷似“空三角征”。一例病人，见左侧三幅图，上矢状窦内静脉血栓形成。*最左侧平扫CT图可见一个“致密血管征”。*中间的图是注射对比剂25秒的CT图像,动脉期的强化并似乎可见上矢状窦强化，实际上这是致密的血栓而形成的高密度。*只有在右侧的一幅图，即注射对比剂45秒的CT图，显示“空三角征”，证明静脉窦内的血栓。不适当的造影剂团注启动时间OntheleftatransverseMIPofphase-contrastimages.

Todifferentiatewhetherthereisahypoplastictransversesinusorthrombosedsinus,youneedtolookatthesourceimages.

Onthesourceimageontherightyoucanseethatthereisnohypoplasia(bluearrow).

Inthiscasetherethrombosisofthelefttransversesinus.HypoplastictransversesinusHypoplasiaandaplasiaoftherightorlefttransversesinusisacommonfinding.

Itcaneasilybemistakenforsinusthrombosis,becauseontheMRAoneofthetransversesinusesismissing.

Whenyoususpect,thatthereisahypoplastictransversesinus,thenyoushouldlookatthesizeofthejugularforamen.

Ontheleftimagesofapatientwithhypoplasiaofthelefttransversesinus.

Noticethesizedifferenceofthejugularforamen.PitfallsinMRIMRI陷阱横窦发育不良右侧或左侧横窦的发育不良或不发育是一个常见的表现.它在MRA上表现为一侧横窦的缺失，从而容易误为窦栓塞。当怀疑一侧横窦发育不良时，应该注意观察该侧颈静脉孔的大小。左侧图病人左侧横窦发育不良。注意：左侧颈静脉孔与右侧的差异。*该病例是左侧横窦的血栓形成。*左图：相位对比的横向的MIP。*为了鉴别左侧横窦或乙状窦发育不良，需要看源图。*其右侧是源图，示左侧的静脉窦并不是发育不良（蓝箭）LowsignalintensityinthrombusNormallywhenthereislowsignalinavein,itisattributedtoflowvoidandasignofpatencyofthevein.

Howeveratsomestageofthethrombusthereisintracellulardeoxyhemoglobin,whichisdarkonT2andmimicsflowvoid.

Ontheleftthereisathrombosedrighttransversesinus.

ThesinushasalowsignalintensityontheT2asaresultoftheintracellulardeoxyhemoglobin.

OnthecontrastenhancedT1itisobviousthatthesinusisfilledwiththrombus.ThrombusinrighttransversesinusisdarkonT2duetointracellulardeoxyhemoglobin(Courtesydr.HowardRowley)Ontheleftanothercasethatdemonstratesthatyoucannotfullyrelyonphasecontrastimaging.

Thesignalintheveindependsonthevelocityoftheflowingbloodandthevelocityencodingbythetechnician.

Onthefarleftapatientwithnonvisualizationofthelefttransversesinus.

Thiscouldbehypoplasia,venousthrombosisorslowflow.

OnthecontrastenhancedT1itisobviousthatthesinusfillswithcontrastandispatent.左图：另一被证实不能充分依赖相位对比MR成像的示例静脉的信号强度依赖于血流速度和扫描技师设置的流速编码(venc)（附：慢血流的venc选择10cm/s）。由于细胞内的脱氧血红蛋白而导致右侧横窦内血栓在T2WI上是黑的。窦内血栓呈低信号正常时，静脉窦由于血流空效应而表现为低信号，并作为静脉通畅的标志。在对比增强T1WI上，显然是横窦充盈对比剂，无可非议。这可能是横窦发育不良，静脉血栓形成或慢血流。更靠左边图：左侧横窦不显示。*对比增强扫描T1WI，明确看到横窦内为血栓所充填（蓝箭）。*右侧横窦血栓形成，在T2WI图像上，由于细胞内脱氧血红蛋白而表现为低信号（红箭）。然而，血栓的某些阶段，由于细胞内的脱氧血红蛋白而导致T2WI低信号，酷似血流空。*左图：栓塞的右侧横窦。PitfallsinTOFimagingare:Signallossduetoin-planeflow.FlowsimulatedbyT1-shinethroughofmethemoglobin

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

Thiscouldeasilybeenmistakenforacentralthrombuswithinthesinus.

Thishoweveristheresultofflowvoid.MR增强扫描上的“流空征”左侧MR增强扫描图上，强化的横窦内有低信号区，这会容易误判为窦内中心性血栓。MR的时间飞跃法（TOF）静脉成像的陷阱是：*由于层面内血流信号丢失（低信号）*由于血栓内的高铁血红蛋白的T1投过效应而形成的模拟血流（附：2D静脉窦血流成像：血栓本应黑

，但却呈白的，形成假血流）。在相位对比成像上，它显然是横窦无疑。因此认为，在诊断静脉血栓形成方面，MRI有许多的假阳性和假阴性。而对比增强MR静脉成像是最可靠的MR技术。CT静脉成像甚至是更可靠，不仅容易而且少有陷阱。然而，这是“流空”所导致的结果。ChronicduralsinusthrombosisandrelatedsyndromesDAVF（硬膜动静脉瘘）ChronicduralsinusthrombosiscanleadtoduralarteriovenousfistulaformationandtoincreasedCSFpressure.ADAVForduralarteriovenousfistulaisanabnormalconnectionbetweenduralarteries,whicharebranchesoftheexternalcarotidwiththevenoussinuses.