DWI在腦部的應(yīng)用

1、Diffusion weighted MR imaging in non-infarct lesions of the brain DWI在非梗塞性腦病變中的應(yīng)用在非梗塞性腦病變中的應(yīng)用林亞南林亞南2012-7- LogoIntroductionv Diffusion weighted imaging (DWI) is based on the sensitivity of MR to microscopic mobility of water molecules within tissues.v DWI基于基于MR對組織內(nèi)水分子微觀運(yùn)動的敏感性對組織內(nèi)水分子微觀運(yùn)動的敏感性v DWI con

2、sists of a DW image and an apparent diffusion coefficient (ADC) map.v DW image, together with qualitative and quantitative assessment of the ADC map has been widely used in the diagnosis of acute cerebral infarction, owing to the reliable distinction of cytotoxic and vasogenic edema.v 由于由于DWI聯(lián)合定性及定量

3、的聯(lián)合定性及定量的ADC圖可以鑒別細(xì)胞毒性和血管源性圖可以鑒別細(xì)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水腫，已廣泛地應(yīng)用在急性腦梗塞的診斷v Edema is a non-specific reaction of brain parenchyme to diffenernt factors ,which can be differentiated by DWI.v DWI可鑒別不同因素導(dǎo)致的腦實(shí)質(zhì)的非特異性反應(yīng)可鑒別不同因素導(dǎo)致的腦實(shí)質(zhì)的非特異性反應(yīng)-水腫水腫 LogoIntroductionv Cytotoxic edema characterized by abnormal

4、cellular uptake of water and myelin edema characterized by intramyelinic accumulation of vacuolated or free water have high signal intensity on the diffusion trace, with decreased ADC as a result of isotropically restricted water diffusion. v On the other hand,vasogenic edema, caused by increased pe

5、rmeability of the bloodbrain barrier, and interstitial edema, caused by subependymal water diffusion in acute hydrocephalus have intermediate signal on the DW image with increased ADCv DWI區(qū)分水腫的性質(zhì)：區(qū)分水腫的性質(zhì)： 細(xì)胞毒性水腫和和髓鞘性水腫細(xì)胞毒性水腫和和髓鞘性水腫由于同向性彌散受限，彌散相呈由于同向性彌散受限，彌散相呈高信號，高信號，ADC值下降；值下降； 血管源性水腫和間質(zhì)性水腫血管源性水腫和間質(zhì)

6、性水腫彌散不受限，彌散相呈中等信號，彌散不受限，彌散相呈中等信號，ADC值升高。值升高。 LogoIntroductionvAlthough DWI has been tried for different organ systems, it has been found its primary use in the central nervous system. vThe most widely used clinical application is in the detection of hyperacute infarcts and the differentiation of acu

7、te or subacute infarction from chronic infarctionv盡管盡管DWI已經(jīng)應(yīng)用在不同系統(tǒng)的器官，但是主已經(jīng)應(yīng)用在不同系統(tǒng)的器官，但是主要應(yīng)用在中樞神經(jīng)系統(tǒng)。要應(yīng)用在中樞神經(jīng)系統(tǒng)。v臨床最廣泛的應(yīng)用是診斷超急性腦梗塞和鑒別臨床最廣泛的應(yīng)用是診斷超急性腦梗塞和鑒別急性或亞急性腦梗塞與陳舊腦梗塞急性或亞急性腦梗塞與陳舊腦梗塞 LogoIntroductionv Recently DWI has been applied to various other cerebral diseases. v 現(xiàn)在現(xiàn)在DWI被應(yīng)用在多種腦部疾病被應(yīng)用在多種腦部疾病v In

8、 this paper，I demonstrate different DWI patterns of non-infarct lesions of the brain which are hyperintense in the diffusion trace image, such as infectious, neoplastic and demyelinating diseases, encephalopathies including hypoxicischemic, hypertensive, eclamptic, toxic, metabolic and mitochondrial

9、 encephalopathies leukodystrophies, vasculitis and vasculopathies, hemorrhage and traumav 本課件講述不同彌散圖像高信號的腦部非梗塞性疾病，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、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高血壓、子癲、中毒、代謝性和線粒體腦病-腦白質(zhì)病腦白質(zhì)病變，血管炎和血管病變、出血及外傷變，血管炎和血管病變、出血及外傷 LogocontentsEncephalopathiesLeuk

10、odystrophiesDemyelinating diseasesVasculitis and vasculopathiesDWINeoplastic lesionsEpilepsyHemorrhageT LogoBrain abscessv Brain abscesses are cystic lesions with a thick, rim-shaped contrast enhancing capsule, surrounded by massive vasogenic edema.v 腦膿腫是一種壁呈環(huán)形強(qiáng)化的囊性病變，伴周圍腦組織廣泛血管腦膿腫是一種壁呈環(huán)形強(qiáng)化的囊性病變，伴周圍

11、腦組織廣泛血管源性水腫。源性水腫。v This appearance on conventional MR images with similar clinical findings can sometimes not be differentiated from cystic necrotic tumors.v 傳統(tǒng)的傳統(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。變相鑒別。 v On the DW image,brain abscesses show very high signal associated with decr

12、eased ADC. The limited diffusion in abscesses are attributed to the high viscosity of the proteinaceous fluid and hypercellularity of the pus consisting of bacteria and inflammatory cellsv 由于膿腫內(nèi)含有粘稠的蛋白質(zhì)液體和大量的細(xì)胞成分（細(xì)菌和炎由于膿腫內(nèi)含有粘稠的蛋白質(zhì)液體和大量的細(xì)胞成分（細(xì)菌和炎性細(xì)胞），性細(xì)胞），DWI彌散受限表現(xiàn)：彌散圖呈高信號，彌散受限表現(xiàn)：彌散圖呈高信號，ADC值下降。值下降。

13、Logo男性，男性，65yFig.1.Cerebral absecess:65 years old ,male.A right temporal lobe absecess with a thick rim enhancing capsule,surrounded by massive edema.On the DWI,the lesion has high signal with partially deceased ADC Logo單純皰疹病毒性腦炎單純皰疹病毒性腦炎(Herpes simplex encephalitis)v Herpes simplex encephalitis is

14、one of the most common viral infections. T2-hyperintense lesions with typical temporal and frontal localization with petechial hemorrhage are characteristic findings.v 單純皰疹病毒性腦炎是最常見的病毒感染性疾病之一，單純皰疹病毒性腦炎是最常見的病毒感染性疾病之一，T2高信號和典型的顳葉、額葉點(diǎn)狀出血是其特征表現(xiàn)。高信號和典型的顳葉、額葉點(diǎn)狀出血是其特征表現(xiàn)。v Conventional MR imaging and clinic

15、al findings might be non-specific, necessitating the proof of evidence of viral DNA by polymerase chain reaction in the cerebrospinal fluid.v 常規(guī)常規(guī)MRI和臨床表現(xiàn)可能是非特異性的，需要腦脊液中和臨床表現(xiàn)可能是非特異性的，需要腦脊液中病毒病毒DNA的的PCR試驗(yàn)來驗(yàn)證試驗(yàn)來驗(yàn)證 Logo單純皰疹病毒性腦炎單純皰疹病毒性腦炎(Herpes simplex encephalitis)vDW image shows high signal in the le

16、sions with usually decreased ADC values representing cytotoxic edema and rarely higher ADC values representing vasogenic edema.v病變病變DWI表現(xiàn)為高信號，表現(xiàn)為高信號，ADC值降低代表細(xì)胞值降低代表細(xì)胞毒性水腫，少數(shù)高毒性水腫，少數(shù)高ADC值代表血管源性水腫值代表血管源性水腫vAreas of cytotoxic edema correspond to a worse outcome compared to areas of vasogenic edema v細(xì)胞毒

17、性水腫與血管源性水腫相比，結(jié)局較差細(xì)胞毒性水腫與血管源性水腫相比，結(jié)局較差 Logo男性，男性，30歲歲Fig.2.Herpes simplex encephalitis: 30 years old, male. (a)shows a hyperintense lesion in the left temporal lobe. hipocampal and parahypocampal gyri, (b) the diffusion trace shows high signal with increased ADC (c). Single voxel proton MR spectrosco

18、py shows decreased N-acetyl aspartate with a prominent lactate peak(d) Logo克雅氏病克雅氏病 （ Creutzfeld-Jakob disease ）v Creutzfeld-Jakob disease is one of several spongiform encephalopathies. Characteristic findings are rapidly progressive dementia, myoclonus and periodic sharp-wave complexes on electroen

19、cephalography.v 克雅病（皮質(zhì)克雅?。ㄆべ|(zhì)-紋狀體紋狀體-脊髓變性脊髓變性 ） 是幾種海綿狀腦病之是幾種海綿狀腦病之一。典型臨床表現(xiàn)為：快速進(jìn)展的癡呆、肌陣攣，腦電一。典型臨床表現(xiàn)為：快速進(jìn)展的癡呆、肌陣攣，腦電圖表現(xiàn)為周期性的銳波。圖表現(xiàn)為周期性的銳波。v MR imaging is helpful in differentiating the two forms of the disease.v 磁共振可以幫助鑒別克雅氏病的兩種類型。磁共振可以幫助鑒別克雅氏病的兩種類型。 Logo克雅氏病克雅氏病 （ Creutzfeld-Jakob disease ）v The spora

20、dic type is characterized by bilateral symmetric hyperintensity in the putamen and head of caudate nucleus on T2-weighted and FLAIR images are characteristic, sometimes associated with bilateral thalamic or cerebral cortical involvement.v Symmetrical high signal of the pulvinar thalami, known as “th

21、e pulvinar sign” is characteristic for the variant type.v 偶發(fā)型偶發(fā)型雙側(cè)殼核及尾狀核頭在雙側(cè)殼核及尾狀核頭在T2加權(quán)和加權(quán)和FLAIR像對像對稱性的高信號是典型表現(xiàn)。丘腦及大腦皮層有時(shí)也可累稱性的高信號是典型表現(xiàn)。丘腦及大腦皮層有時(shí)也可累及及 變異型變異型“丘腦后結(jié)節(jié)征丘腦后結(jié)節(jié)征”即雙側(cè)丘腦后結(jié)節(jié)對稱性高信即雙側(cè)丘腦后結(jié)節(jié)對稱性高信號。號。 Logo克雅氏病克雅氏病 （ Creutzfeld-Jakob disease ） Although thalamic high signal may be seen in both types

22、, it is less pronounced than in the caudate and putamen in the sporadic type, whereas it is the most prominent sign in the variant type 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(gè)顯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(gè)顯著的特征著的特征v Diffusion trace image shows high signal

23、with decreased ADC .v The restricted diffusion can be attributed to the compartmentalization of water molecules within the clustered vacuoles in the gray matter. DWI表現(xiàn)為彌散受限伴表現(xiàn)為彌散受限伴ADC值下降。這與灰質(zhì)中簇狀分布的液泡值下降。這與灰質(zhì)中簇狀分布的液泡中的水分子有關(guān)。中的水分子有關(guān)。v Persistence of high signal on the DW image is helpful in different

24、iating from infarctv 克雅病克雅病DWI長期表現(xiàn)為彌散受限，可與腦梗塞相鑒別。長期表現(xiàn)為彌散受限，可與腦梗塞相鑒別。 Logo女性，女性，55歲歲Fig. 3. CreutzfeldtJacob disease: 55 years old, female. (a) FLAIR imaging shows diffuse high signal in both cerebral cortices sparing the sensorimotor cortices, with high signal on the DW image (b) LogocontentsEncepha

25、lopathiesLeukodystrophiesDemyelinating diseasesVasculitis and vasculopathiesDWINeoplastic lesionsEpilepsyHemorrhageT LogoTumorsTumorsPrimary tumors M Logo Primary tumors（原發(fā)腫瘤）v Brain neoplasms show variable signal on the DW image and the ADC map. Tumors with higher cellularity or higher grade show i

26、ncreased signal on the DW image and a marked reduction in ADC values.v原發(fā)性腦腫瘤的原發(fā)性腦腫瘤的DWI表現(xiàn)多變，細(xì)胞成分多或表現(xiàn)多變，細(xì)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值明顯降低值明顯降低v In addition to the hypercellularity which causes increased intracellular water, the low ADC values are also related to the decreased extra

27、cellular fluidv除了細(xì)胞增殖所致的細(xì)胞內(nèi)水增多，低除了細(xì)胞增殖所致的細(xì)胞內(nèi)水增多，低ADC值值也與細(xì)胞外水減少有關(guān)也與細(xì)胞外水減少有關(guān) Logo Primary tumors（原發(fā)腫瘤）vLow grade gliomas, because of their low cellularity, have a significantly higher ADC values compared to high grade gliomas and lymphomasv而低級別膠質(zhì)瘤因?yàn)榧?xì)胞成分少，其而低級別膠質(zhì)瘤因?yàn)榧?xì)胞成分少，其ADC值明值明顯高于高級別膠質(zhì)瘤和淋巴瘤顯高于高級別膠質(zhì)瘤和

28、淋巴瘤vConjoint evaluation of conventional MR sequences and DWI are of great importance in atypical casesv有些研究表明傳統(tǒng)有些研究表明傳統(tǒng)MR序列與序列與DWI相結(jié)合對非相結(jié)合對非典型腫瘤病例的診斷有重要意義典型腫瘤病例的診斷有重要意義 Logo Primary tumors（原發(fā)腫瘤）v Lymphomas are highly cellular tumors.DWI of which is controversial. Typical MR findings are slightly hyp

29、erintense lesions compared to normal brain tissue on T2-weighted images usually in the cerebral hemispheres, basal ganglia and thalamus, with ring-shaped or diffuse enhancement.v 淋巴瘤富含細(xì)胞，其淋巴瘤富含細(xì)胞，其DWI表現(xiàn)有爭議。常規(guī)表現(xiàn)有爭議。常規(guī)MRI表現(xiàn)為表現(xiàn)為大腦半球、基底節(jié)區(qū)及丘腦大腦半球、基底節(jié)區(qū)及丘腦T2WI稍微高信號，邊緣或稍微高信號，邊緣或彌漫性增強(qiáng)彌漫性增強(qiáng)v Cerebral lymphoma

30、s without contrast enhancement are regarded as cerebral manifestation of a systemic disease, namely angiotropic large cell lymphoma or intravascular lymphomatosisv 沒有增強(qiáng)的腦淋巴瘤病是系統(tǒng)性疾病的腦部表現(xiàn)，稱作沒有增強(qiáng)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(xì)胞淋巴瘤或血管內(nèi)淋巴瘤病噬血管性大細(xì)胞淋巴瘤或血管內(nèi)淋巴瘤病 Logo Primary tumors（原發(fā)腫瘤）v K uker et al have found

31、that DWI was helpful in differentiating primary central nervous system lymphomas from angiotropic large cell lymphoma which is frequently accompanied by diffusion abnormalities due to brain ischemia. v K等發(fā)現(xiàn)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(xì)胞淋巴瘤（伴隨腦缺血所致的擴(kuò)散異常）細(xì)胞淋巴瘤（伴隨腦缺血所致的擴(kuò)散異常）v In

32、 a study with seven central nervous system T-cell lymphomas,three patients showed hyperintensity and four patients showed isointensity in the DW image and ADC maps.v 有研究，有研究，7例中樞神經(jīng)系統(tǒng)例中樞神經(jīng)系統(tǒng)T細(xì)胞淋巴瘤中，細(xì)胞淋巴瘤中，3例呈高信號，例呈高信號，4例呈例呈等信號等信號v In some other studies it has been reported that ADC values of the prim

33、ary central nervous system lymphomas were lower than other intracerebral tumors, close to acute infarctv 其他的研究報(bào)道原發(fā)中樞神經(jīng)系統(tǒng)淋巴瘤比其他腦內(nèi)腫瘤的其他的研究報(bào)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，與急性腦梗塞相近值低，與急性腦梗塞相近 Logo Primary tumors（原發(fā)腫瘤）v Epidermoid cysts are rare congenital lesions arising from the inclusion of ectodermal tiss

34、ue into the neural tube. Cere-bellopontine angle is the most common location. v 表皮樣囊腫是少見的起源于外胚層組織的先天性疾病，橋小腦角表皮樣囊腫是少見的起源于外胚層組織的先天性疾病，橋小腦角區(qū)是最常見的發(fā)病部位區(qū)是最常見的發(fā)病部位v Typical MR imaging findings are well-defined, lobulated masses, slightly hyperintense or isointense to the cerebrospinal fluid on T1-and T2-we

35、ighted images with no internal contrast enhancement.v 典型的典型的MRI表現(xiàn)是輪廓清楚、分葉狀腫塊、表現(xiàn)是輪廓清楚、分葉狀腫塊、T1和和T2加權(quán)成像與腦加權(quán)成像與腦脊液相比，呈輕度高或等信號，內(nèi)部沒有強(qiáng)化脊液相比，呈輕度高或等信號，內(nèi)部沒有強(qiáng)化v On proton density and FLAIR images, the lesions are slightly hyperintense to the cerebrospinal fluid. The lesions show high signal on the DW image wi

36、th mixed signal on the ADC mapv 在質(zhì)子密度和在質(zhì)子密度和FLAIR成像，病變與腦脊液相比呈輕度高信號。病成像，病變與腦脊液相比呈輕度高信號。病變在變在DWI上呈高信號，上呈高信號，ADC圖呈混雜信號圖呈混雜信號 Logo Primary tumors（原發(fā)腫瘤）v Initial studies have attributed the high signal in DWI to the increased cellularity and restricted diffusion of water molecules due to high viscosity o

37、f the fluid containing keratohyalin and cholesterol crystals. v 最初的研究把最初的研究把DWI高信號歸因于細(xì)胞增殖和限制水分子高信號歸因于細(xì)胞增殖和限制水分子的擴(kuò)散歸因于透明角質(zhì)蛋白與膽固醇結(jié)晶的高粘度的擴(kuò)散歸因于透明角質(zhì)蛋白與膽固醇結(jié)晶的高粘度v However, recent reports suggest that this is due to the T2 shine through effect.v 但是，最近的報(bào)道稱這歸因于但是，最近的報(bào)道稱這歸因于T2的透過效應(yīng)的透過效應(yīng)v DWI is not only helpf

38、ul in differentiating epidermoids from arachnoid cysts, but also differentiating residual or recurrent tumor from cerebrospinal fluid-filled cavities in the postoperative patient v DWI不僅有助于鑒別表皮樣囊腫與蛛網(wǎng)膜囊腫，還可以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鑒別殘余或復(fù)發(fā)腫瘤與腦脊液填充的空腔 Logo Metastases(轉(zhuǎn)移瘤)v Metastases sh

39、ow variable signal (generally iso- or hypointense, occasionally hyperintense) in the DWI .v Rarely high signal intensity in the DW image with decreased ADC may be seen, due to mostly the hypercellularity of the lesion，extracelular methemoglobin or sometimes increased protein concentration in the for

40、m of highly viscous mucin in cystic metastases v 轉(zhuǎn)移瘤轉(zhuǎn)移瘤DWI表現(xiàn)也多變，彌散相多為等或低信號，少數(shù)表現(xiàn)也多變，彌散相多為等或低信號，少數(shù)高信號（源于細(xì)胞豐富、血管外正鐵血紅蛋白或囊性轉(zhuǎn)高信號（源于細(xì)胞豐富、血管外正鐵血紅蛋白或囊性轉(zhuǎn)移瘤中高粘度蛋白移瘤中高粘度蛋白) Logo Metastases(轉(zhuǎn)移瘤)v In case of multiple lesions in the setting of a known primary malignancy, metastatic tumors are not a diagnostic challenge.