DWI在腦部的應(yīng)用課件

DiffusionweightedMRimaging

innon-infarctlesionsofthebrain

DWI在非梗塞性腦病變中的應(yīng)用林亞南2012-7-11IntroductionDiffusionweightedimaging(DWI)isbasedonthesensitivityofMRtomicroscopicmobilityofwatermoleculeswithintissues.DWI基于MR對組織內(nèi)水分子微觀運動的敏感性DWIconsistsofaDWimageandanapparentdiffusioncoefficient(ADC)map.DWimage,togetherwithqualitativeandquantitativeassessmentoftheADCmaphasbeenwidelyusedinthediagnosisofacutecerebralinfarction,owingtothereliabledistinctionofcytotoxicandvasogenicedema.由于DWI聯(lián)合定性及定量的ADC圖可以鑒別細胞毒性和血管源性水腫，已廣泛地應(yīng)用在急性腦梗塞的診斷Edemaisanon-specificreactionofbrainparenchymetodiffenerntfactors,whichcanbedifferentiatedbyDWI.DWI可鑒別不同因素導(dǎo)致的腦實質(zhì)的非特異性反應(yīng)--水腫/mobanCompanyLogoIntroductionCytotoxicedema–characterizedbyabnormalcellularuptakeofwaterandmyelinedema–characterizedbyintramyelinicaccumulationofvacuolatedorfreewater–havehighsignalintensityonthediffusiontrace,withdecreasedADCasaresultofisotropicallyrestrictedwaterdiffusion.Ontheotherhand,vasogenicedema,causedbyincreasedpermeabilityoftheblood–brainbarrier,andinterstitialedema,causedbysubependymalwaterdiffusioninacutehydrocephalushaveintermediatesignalontheDWimagewithincreasedADCDWI區(qū)分水腫的性質(zhì)：細胞毒性水腫和和髓鞘性水腫——由于同向性彌散受限，彌散相呈高信號，ADC值下降；血管源性水腫和間質(zhì)性水腫——彌散不受限，彌散相呈中等信號，ADC值升高。/mobanCompanyLogoIntroductionRecentlyDWIhasbeenappliedtovariousothercerebraldiseases.現(xiàn)在DWI被應(yīng)用在多種腦部疾病Inthispaper，IdemonstratedifferentDWIpatternsofnon-infarctlesionsofthebrainwhicharehyperintenseinthediffusiontraceimage,suchasinfectious,neoplasticanddemyelinatingdiseases,encephalopathies–includinghypoxic–ischemic,hypertensive,eclamptic,toxic,metabolicandmitochondrialencephalopathies–leukodystrophies,vasculitisandvasculopathies,hemorrhageandtrauma本課件講述不同彌散圖像高信號的腦部非梗塞性疾病，例如炎癥、腫瘤、脫髓鞘疾病、腦病變包括缺血缺氧性、高血壓、子癲、中毒、代謝性和線粒體腦病-腦白質(zhì)病變，血管炎和血管病變、出血及外傷/mobanCompanyLogocontentsEncephalopathiesLeukodystrophiesDemyelinatingdiseasesVasculitisandvasculopathiesDWIInfectionNeoplasticlesionsEpilepsyHemorrhageT/mobanCompanyLogoBrainabscessBrainabscessesarecysticlesionswithathick,rim-shapedcontrastenhancingcapsule,surroundedbymassivevasogenicedema.腦膿腫是一種壁呈環(huán)形強化的囊性病變，伴周圍腦組織廣泛血管源性水腫。ThisappearanceonconventionalMRimageswithsimilarclinicalfindingscansometimesnotbedifferentiatedfromcysticnecrotictumors.傳統(tǒng)的MRI可能不能使其與臨床表現(xiàn)相似的囊性壞死性腫瘤性病變相鑒別。

OntheDWimage,brainabscessesshowveryhighsignalassociatedwithdecreasedADC.Thelimiteddiffusioninabscessesareattributedtothehighviscosityoftheproteinaceousfluidandhypercellularityofthepusconsistingofbacteriaandinflammatorycells由于膿腫內(nèi)含有粘稠的蛋白質(zhì)液體和大量的細胞成分（細菌和炎性細胞），DWI彌散受限表現(xiàn)：彌散圖呈高信號，ADC值下降。/mobanCompanyLogo男性，65yFig.1.Cerebralabsecess:65yearsold,male.Arighttemporallobeabsecesswithathickrimenhancingcapsule,surroundedbymassiveedema.OntheDWI,thelesionhashighsignalwithpartiallydeceasedADC./mobanCompanyLogo單純皰疹病毒性腦炎(Herpessimplexencephalitis)DWimageshowshighsignalinthelesionswithusuallydecreasedADCvaluesrepresentingcytotoxicedemaandrarelyhigherADCvaluesrepresentingvasogenicedema.病變DWI表現(xiàn)為高信號，ADC值降低代表細胞毒性水腫，少數(shù)高ADC值代表血管源性水腫Areasofcytotoxicedemacorrespondtoaworseoutcomecomparedtoareasofvasogenicedema細胞毒性水腫與血管源性水腫相比，結(jié)局較差/mobanCompanyLogo克雅氏病（Creutzfeld-Jakobdisease）Creutzfeld-Jakobdiseaseisoneofseveralspongiform

encephalopathies.Characteristicfindingsarerapidlyprogressivedementia,myoclonusandperiodicsharp-wavecomplexes

onelectroencephalography.克雅?。ㄆべ|(zhì)-紋狀體-脊髓變性）是幾種海綿狀腦病之一。典型臨床表現(xiàn)為：快速進展的癡呆、肌陣攣，腦電圖表現(xiàn)為周期性的銳波。MRimagingishelpfulindifferentiatingthetwoformsofthedisease.磁共振可以幫助鑒別克雅氏病的兩種類型。

/mobanCompanyLogo克雅氏?。–reutzfeld-Jakobdisease）Althoughthalamichighsignalmaybeseeninbothtypes,itislesspronouncedthaninthecaudateandputameninthesporadictype,whereasitisthemostprominentsigninthevarianttype盡管兩種類型均可見丘腦的高信號，但是在偶發(fā)型中，丘腦沒有殼核和尾狀核的高信號顯著，而在變異型中丘腦的高信號是一個顯著的特征DiffusiontraceimageshowshighsignalwithdecreasedADC.Therestricteddiffusioncanbeattributedtothecompartmentalizationofwatermoleculeswithintheclusteredvacuolesinthegraymatter.DWI表現(xiàn)為彌散受限伴ADC值下降。這與灰質(zhì)中簇狀分布的液泡中的水分子有關(guān)。PersistenceofhighsignalontheDWimageishelpfulindifferentiatingfrominfarct克雅病DWI長期表現(xiàn)為彌散受限，可與腦梗塞相鑒別。/mobanCompanyLogo女性，55歲Fig.3.Creutzfeldt–Jacobdisease:55yearsold,female.(a)FLAIRimagingshowsdiffusehighsignalinbothcerebralcorticessparingthesensorimotorcortices,withhighsignalontheDWimage(b)/mobanCompanyLogocontentsEncephalopathiesLeukodystrophiesDemyelinatingdiseasesVasculitisandvasculopathiesDWIInfectionNeoplasticlesionsEpilepsyHemorrhageT/mobanCompanyLogoTumorsTumorsPrimarytumors

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Primarytumors（原發(fā)腫瘤）BrainneoplasmsshowvariablesignalontheDWimageandtheADCmap.TumorswithhighercellularityorhighergradeshowincreasedsignalontheDWimageandamarkedreductioninADCvalues.原發(fā)性腦腫瘤的DWI表現(xiàn)多變，細胞成分多或者是高級別腫瘤通常表現(xiàn)為彌散圖高信號伴ADC值明顯降低Inadditiontothehypercellularitywhichcausesincreasedintracellularwater,thelowADCvaluesarealsorelatedtothedecreasedextracellularfluid除了細胞增殖所致的細胞內(nèi)水增多，低ADC值也與細胞外水減少有關(guān)/mobanCompanyLogo

Primarytumors（原發(fā)腫瘤）Lymphomasarehighlycellulartumors.DWIofwhichiscontroversial.TypicalMRfindingsareslightlyhyperintenselesionscomparedtonormalbraintissueonT2-weightedimagesusuallyinthecerebralhemispheres,basalgangliaandthalamus,withring-shapedordiffuseenhancement.淋巴瘤富含細胞，其DWI表現(xiàn)有爭議。常規(guī)MRI表現(xiàn)為大腦半球、基底節(jié)區(qū)及丘腦T2WI稍微高信號，邊緣或彌漫性增強Cerebrallymphomaswithoutcontrastenhancementareregardedascerebralmanifestationofasystemicdisease,namelyangiotropiclargecelllymphomaorintravascularlymphomatosis沒有增強的腦淋巴瘤病是系統(tǒng)性疾病的腦部表現(xiàn)，稱作噬血管性大細胞淋巴瘤或血管內(nèi)淋巴瘤病/mobanCompanyLogo

Primarytumors（原發(fā)腫瘤）K¨ukeretalhavefoundthatDWIwashelpfulindifferentiatingprimarycentralnervoussystemlymphomasfromangiotropiclargecelllymphomawhichisfrequentlyaccompaniedbydiffusionabnormalitiesduetobrainischemia.K等發(fā)現(xiàn)DWI有助于鑒別原發(fā)性中樞神經(jīng)系統(tǒng)淋巴瘤與噬血管性大細胞淋巴瘤（伴隨腦缺血所致的擴散異常）InastudywithsevencentralnervoussystemT-celllymphomas,threepatientsshowedhyperintensityandfourpatientsshowedisointensityintheDWimageandADCmaps.有研究，7例中樞神經(jīng)系統(tǒng)T細胞淋巴瘤中，3例呈高信號，4例呈等信號InsomeotherstudiesithasbeenreportedthatADCvaluesoftheprimarycentralnervoussystemlymphomaswerelowerthanotherintracerebraltumors,closetoacuteinfarct其他的研究報道原發(fā)中樞神經(jīng)系統(tǒng)淋巴瘤比其他腦內(nèi)腫瘤的ADC值低，與急性腦梗塞相近/mobanCompanyLogo

Primarytumors（原發(fā)腫瘤）InitialstudieshaveattributedthehighsignalinDWItotheincreasedcellularityandrestricteddiffusionofwatermoleculesduetohighviscosityofthefluidcontainingkeratohyalinandcholesterolcrystals.最初的研究把DWI高信號歸因于細胞增殖和限制水分子的擴散歸因于透明角質(zhì)蛋白與膽固醇結(jié)晶的高粘度However,recentreportssuggestthatthisisduetotheT2shinethrougheffect.但是，最近的報道稱這歸因于T2的透過效應(yīng)DWIisnotonlyhelpfulindifferentiatingepidermoidsfromarachnoidcysts,butalsodifferentiatingresidualorrecurrenttumorfromcerebrospinalfluid-filledcavitiesinthepostoperativepatientDWI不僅有助于鑒別表皮樣囊腫與蛛網(wǎng)膜囊腫，還可以鑒別殘余或復(fù)發(fā)腫瘤與腦脊液填充的空腔/mobanCompanyLogo

Metastases(轉(zhuǎn)移瘤)Metastasesshowvariablesignal(generallyiso-orhypointense,occasionallyhyperintense)intheDWI.RarelyhighsignalintensityintheDWimagewithdecreasedADCmaybeseen,duetomostlythehypercellularityofthelesion，extracelularmethemoglobinorsometimesincreasedproteinconcentrationintheformofhighlyviscousmuc