DWI在脑部的应用PPT参考幻灯片

DiffusionweightedMRimaginginnon-infarctlesionsofthebrainDWI在非梗塞性脑病变中的应用,林亚南2012-7-11,Introduction,Diffusionweightedimaging(DWI)isbasedonthesensitivityofMRtomicroscopicmobilityofwatermoleculeswithintissues.DWI基于MR对组织内水分子微观运动的敏感性DWIconsistsofaDWimageandanapparentdiffusioncoefficient(ADC)map.DWimage,togetherwithqualitativeandquantitativeassessmentoftheADCmaphasbeenwidelyusedinthediagnosisofacutecerebralinfarction,owingtothereliabledistinctionofcytotoxicandvasogenicedema.由于DWI联合定性及定量的ADC图可以鉴别细胞毒性和血管源性水肿，已广泛地应用在急性脑梗塞的诊断Edemaisanon-specificreactionofbrainparenchymetodiffenerntfactors,whichcanbedifferentiatedbyDWI.DWI可鉴别不同因素导致的脑实质的非特异性反应-水肿,2,Introduction,Cytotoxicedemacharacterizedbyabnormalcellularuptakeofwaterandmyelinedemacharacterizedbyintramyelinicaccumulationofvacuolatedorfreewaterhavehighsignalintensityonthediffusiontrace,withdecreasedADCasaresultofisotropicallyrestrictedwaterdiffusion.Ontheotherhand,vasogenicedema,causedbyincreasedpermeabilityofthebloodbrainbarrier,andinterstitialedema,causedbysubependymalwaterdiffusioninacutehydrocephalushaveintermediatesignalontheDWimagewithincreasedADCDWI区分水肿的性质：细胞毒性水肿和和髓鞘性水肿由于同向性弥散受限，弥散相呈高信号，ADC值下降；血管源性水肿和间质性水肿弥散不受限，弥散相呈中等信号，ADC值升高。,3,Introduction,AlthoughDWIhasbeentriedfordifferentorgansystems,ithasbeenfounditsprimaryuseinthecentralnervoussystem.Themostwidelyusedclinicalapplicationisinthedetectionofhyperacuteinfarctsandthedifferentiationofacuteorsubacuteinfarctionfromchronicinfarction尽管DWI已经应用在不同系统的器官，但是主要应用在中枢神经系统。临床最广泛的应用是诊断超急性脑梗塞和鉴别急性或亚急性脑梗塞与陈旧脑梗塞,4,Introduction,RecentlyDWIhasbeenappliedtovariousothercerebraldiseases.现在DWI被应用在多种脑部疾病Inthispaper，IdemonstratedifferentDWIpatternsofnon-infarctlesionsofthebrainwhicharehyperintenseinthediffusiontraceimage,suchasinfectious,neoplasticanddemyelinatingdiseases,encephalopathiesincludinghypoxicischemic,hypertensive,eclamptic,toxic,metabolicandmitochondrialencephalopathiesleukodystrophies,vasculitisandvasculopathies,hemorrhageandtrauma本课件讲述不同弥散图像高信号的脑部非梗塞性疾病，例如炎症、肿瘤、脱髓鞘疾病、脑病变包括缺血缺氧性、高血压、子癫、中毒、代谢性和线粒体脑病-脑白质病变，血管炎和血管病变、出血及外伤,5,contents,Encephalopathies,Leukodystrophies,Demyelinatingdiseases,Vasculitisandvasculopathies,DWI,Infection,Neoplasticlesions,Epilepsy,Hemorrhage,Trauma,6,Brainabscess,Brainabscessesarecysticlesionswithathick,rim-shapedcontrastenhancingcapsule,surroundedbymassivevasogenicedema.脑脓肿是一种壁呈环形强化的囊性病变，伴周围脑组织广泛血管源性水肿。ThisappearanceonconventionalMRimageswithsimilarclinicalfindingscansometimesnotbedifferentiatedfromcysticnecrotictumors.传统的MRI可能不能使其与临床表现相似的囊性坏死性肿瘤性病变相鉴别。OntheDWimage,brainabscessesshowveryhighsignalassociatedwithdecreasedADC.Thelimiteddiffusioninabscessesareattributedtothehighviscosityoftheproteinaceousfluidandhypercellularityofthepusconsistingofbacteriaandinflammatorycells由于脓肿内含有粘稠的蛋白质液体和大量的细胞成分（细菌和炎性细胞），DWI弥散受限表现：弥散图呈高信号，ADC值下降。,7,男性，65y,Fig.1.Cerebralabsecess:65yearsold,male.Arighttemporallobeabsecesswithathickrimenhancingcapsule,surroundedbymassiveedema.OntheDWI,thelesionhashighsignalwithpartiallydeceasedADC.,8,单纯疱疹病毒性脑炎(Herpessimplexencephalitis),Herpessimplexencephalitisisoneofthemostcommonviralinfections.T2-hyperintenselesionswithtypicaltemporalandfrontallocalizationwithpetechialhemorrhagearecharacteristicfindings.单纯疱疹病毒性脑炎是最常见的病毒感染性疾病之一，T2高信号和典型的颞叶、额叶点状出血是其特征表现。ConventionalMRimagingandclinicalfindingsmightbenon-specific,necessitatingtheproofofevidenceofviralDNAbypolymerasechainreactioninthecerebrospinalfluid.常规MRI和临床表现可能是非特异性的，需要脑脊液中病毒DNA的PCR试验来验证,9,单纯疱疹病毒性脑炎(Herpessimplexencephalitis),DWimageshowshighsignalinthelesionswithusuallydecreasedADCvaluesrepresentingcytotoxicedemaandrarelyhigherADCvaluesrepresentingvasogenicedema.病变DWI表现为高信号，ADC值降低代表细胞毒性水肿，少数高ADC值代表血管源性水肿Areasofcytotoxicedemacorrespondtoaworseoutcomecomparedtoareasofvasogenicedema细胞毒性水肿与血管源性水肿相比，结局较差,10,男性，30岁,Fig.2.Herpessimplexencephalitis:30yearsold,male.(a)showsahyperintenselesioninthelefttemporallobe.hipocampalandparahypocampalgyri,(b)thediffusiontraceshowshighsignalwithincreasedADC(c).SinglevoxelprotonMRspectroscopyshowsdecreasedN-acetylaspartatewithaprominentlactatepeak(d).,11,克雅氏病（Creutzfeld-Jakobdisease）,Creutzfeld-Jakobdiseaseisoneofseveralspongiformencephalopathies.Characteristicfindingsarerapidlyprogressivedementia,myoclonusandperiodicsharp-wavecomplexesonelectroencephalography.克雅病（皮质-纹状体-脊髓变性）是几种海绵状脑病之一。典型临床表现为：快速进展的痴呆、肌阵挛，脑电图表现为周期性的锐波。MRimagingishelpfulindifferentiatingthetwoformsofthedisease.磁共振可以帮助鉴别克雅氏病的两种类型。,12,克雅氏病（Creutzfeld-Jakobdisease）,ThesporadictypeischaracterizedbybilateralsymmetrichyperintensityintheputamenandheadofcaudatenucleusonT2-weightedandFLAIRimagesarecharacteristic,sometimesassociatedwithbilateralthalamicorcerebralcorticalinvolvement.Symmetricalhighsignalofthepulvinarthalami,knownas“thepulvinarsign”ischaracteristicforthevarianttype.偶发型双侧壳核及尾状核头在T2加权和FLAIR像对称性的高信号是典型表现。丘脑及大脑皮层有时也可累及变异型“丘脑后结节征”即双侧丘脑后结节对称性高信号。,13,克雅氏病（Creutzfeld-Jakobdisease）,Althoughthalamichighsignalmaybeseeninbothtypes,itislesspronouncedthaninthecaudateandputameninthesporadictype,whereasitisthemostprominentsigninthevarianttype尽管两种类型均可见丘脑的高信号，但是在偶发型中，丘脑没有壳核和尾状核的高信号显著，而在变异型中丘脑的高信号是一个显著的特征DiffusiontraceimageshowshighsignalwithdecreasedADC.Therestricteddiffusioncanbeattributedtothecompartmentalizationofwatermoleculeswithintheclusteredvacuolesinthegraymatter.DWI表现为弥散受限伴ADC值下降。这与灰质中簇状分布的液泡中的水分子有关。PersistenceofhighsignalontheDWimageishelpfulindifferentiatingfrominfarct克雅病DWI长期表现为弥散受限，可与脑梗塞相鉴别。,14,女性，55岁,Fig.3.CreutzfeldtJacobdisease:55yearsold,female.(a)FLAIRimagingshowsdiffusehighsignalinbothcerebralcorticessparingthesensorimotorcortices,withhighsignalontheDWimage(b),15,contents,Encephalopathies,Leukodystrophies,Demyelinatingdiseases,Vasculitisandvasculopathies,DWI,Infection,Neoplasticlesions,Epilepsy,Hemorrhage,Trauma,16,Tumors,Tumors,Primarytumors,Metastases,17,Primarytumors（原发肿瘤）,BrainneoplasmsshowvariablesignalontheDWimageandtheADCmap.TumorswithhighercellularityorhighergradeshowincreasedsignalontheDWimageandamarkedreductioninADCvalues.原发性脑肿瘤的DWI表现多变，细胞成分多或者是高级别肿瘤通常表现为弥散图高信号伴ADC值明显降低Inadditiontothehypercellularitywhichcausesincreasedintracellularwater,thelowADCvaluesarealsorelatedtothedecreasedextracellularfluid除了细胞增殖所致的细胞内水增多，低ADC值也与细胞外水减少有关,18,Primarytumors（原发肿瘤）,Lowgradegliomas,becauseoftheirlowcellularity,haveasignificantlyhigherADCvaluescomparedtohighgradegliomasandlymphomas而低级别胶质瘤因为细胞成分少，其ADC值明显高于高级别胶质瘤和淋巴瘤ConjointevaluationofconventionalMRsequencesandDWIareofgreatimportanceinatypicalcases有些研究表明传统MR序列与DWI相结合对非典型肿瘤病例的诊断有重要意义,19,Primarytumors（原发肿瘤）,Lymphomasarehighlycellulartumors.DWIofwhichiscontroversial.TypicalMRfindingsareslightlyhyperintenselesionscomparedtonormalbraintissueonT2-weightedimagesusuallyinthecerebralhemispheres,basalgangliaandthalamus,withring-shapedordiffuseenhancement.淋巴瘤富含细胞，其DWI表现有争议。常规MRI表现为大脑半球、基底节区及丘脑T2WI稍微高信号，边缘或弥漫性增强Cerebrallymphomaswithoutcontrastenhancementareregardedascerebralmanifestationofasystemicdisease,namelyangiotropiclargecelllymphomaorintravascularlymphomatosis没有增强的脑淋巴瘤病是系统性疾病的脑部表现，称作噬血管性大细胞淋巴瘤或血管内淋巴瘤病,20,Primarytumors（原发肿瘤）,KukeretalhavefoundthatDWIwashelpfulindifferentiatingprimarycentralnervoussystemlymphomasfromangiotropiclargecelllymphomawhichisfrequentlyaccompaniedbydiffusionabnormalitiesduetobrainischemia.K等发现DWI有助于鉴别原发性中枢神经系统淋巴瘤与噬血管性大细胞淋巴瘤（伴随脑缺血所致的扩散异常）InastudywithsevencentralnervoussystemT-celllymphomas,threepatientsshowedhyperintensityandfourpatientsshowedisointensityintheDWimageandADCmaps.有研究，7例中枢神经系统T细胞淋巴瘤中，3例呈高信号，4例呈等信号InsomeotherstudiesithasbeenreportedthatADCvaluesoftheprimarycentralnervoussystemlymphomaswerelowerthanotherintracerebraltumors,closetoacuteinfarct其他的研究报道原发中枢神经系统淋巴瘤比其他脑内肿瘤的ADC值低，与急性脑梗塞相近,21,Primarytumors（原发肿瘤）,Epidermoidcystsarerarecongenitallesionsarisingfromtheinclusionofectodermaltissueintotheneuraltube.Cere-bellopontineangleisthemostcommonlocation.表皮样囊肿是少见的起源于外胚层组织的先天性疾病，桥小脑角区是最常见的发病部位TypicalMRimagingfindingsarewell-defined,lobulatedmasses,slightlyhyperintenseorisointensetothecerebrospinalfluidonT1-andT2-weightedimageswithnointernalcontrastenhancement.典型的MRI表现是轮廓清楚、分叶状肿块、T1和T2加权成像与脑脊液相比，呈轻度高或等信号，内部没有强化OnprotondensityandFLAIRimages,thelesionsareslightlyhyperintensetothecerebrospinalfluid.ThelesionsshowhighsignalontheDWimagewithmixedsignalontheADCmap在质子密度和FLAIR成像，病变与脑脊液相比呈轻度高信号。病变在DWI上呈高信号，ADC图呈混杂信号,22,Primarytumors（原发肿瘤）,InitialstudieshaveattributedthehighsignalinDWItotheincreasedcellularityandrestricteddiffusionofwatermoleculesduetohighviscosityofthefluidcontainingkeratohyalinandcholesterolcrystals.最初的研究把DWI高信号归因于细胞增殖和限制水分子的扩散归因于透明角质蛋白与胆固醇结晶的高粘度However,recentreportssuggestthatthisisduetotheT2shinethrougheffect.但是，最近的报道称这归因于T2的透过效应DWIisnotonlyhelpfulindifferentiatingepidermoidsfromarachnoidcysts,butalsodifferentiatingresidualorrecurrenttumorfromcerebrospinalfluid-filledcavitiesinthepostoperativepatientDWI不仅有助于鉴别表皮样囊肿与蛛网膜囊肿，还可以鉴别残余或复发肿瘤与脑脊液填充的空腔,23,Metastases(转移瘤),Metastasesshowvariablesignal(generallyiso-orhypointense,occasionallyhyperintense)intheDWI.RarelyhighsignalintensityintheDWimagewithdecreasedADCmaybeseen,duetomostlythehypercellularityofthelesion，extracelularmethemoglobinorsometimesincreasedproteinconcentrationintheformofhighlyviscousmucinincysticmetastases转移瘤DWI表现也多变，弥散相多为等或低信号，少数高信号（源于细胞丰富、血管外正铁血红蛋白或囊性转移瘤中高粘度蛋白),24,Metastases(转移瘤),Incaseofmultiplelesionsinthesettingofaknownprimarymalignancy,metastatictumorsarenotadiagnosticchallenge.多发病变中，如果有明确的原发恶性肿瘤，转移瘤很容易诊断However,incaseo