中枢神经系统影像学诊断

第十八章中枢神经系统影像学诊断RadiologyofCentralNervousSystem河北医科大学第三医院HebeiMedicalUniversity3rdHospital中枢神经系统脑脊髓检查方法Modalities头颅MRI头颅CTECT，emissioncomputedtomography–SPECT,singlephotonemissioncomputedtomography–PET,positronemissiontomography脑血管造影,cerebralangiography经颅Doppler,transcranialdoppler，TCD头颅平片,plainfilm最好的检查方法，为首选Firstchoice检查方法Modalities显示脑实质parenchyma–MRI，MagneticResonanceImaging–CT,ComputedTomography检查方法Modalities显示脑实质Parenchyma–MRI是颅脑最好的检查方法firstchoice优点：advantage–软组织分辨率最高–任意面成像，有利于观察解剖关系–检查序列多•T1WI,T2WI,PDWI等缺点：disadvantage–钙化、骨化、早期出血灶显示不如CT–价格贵检查方法Modalities显示脑实质parenchyma–CT是最常用的检查方法优点–显示骨和钙化一般比MRI好–显示早期出血比MRI好缺点–对脑组织的分辨率不如MRI检查方法Modalities显示脑血管bloodvessel–脑血管造影cerebralangiographyDSA，digitalsubstractiveangiography–MRA,magneticresonanceangiography–CTA,computedtomographyangiography–TCD,transcranialDopplerDSAMRATranscranialDoppler，TCDCTangiography检查方法显示脑功能brainfunction–DWI,diffusionweightedimaging–PWI,perfusionweightedimaging–BOLD,bloodoxygenationleveldependent–ECT,emissioncomputedtomographyDWIincerebralinfarctAbsoluteCBF(A)τD=timefortheloweredgeofthebolustoreachthetissue(B)Apatientwithrightcarotidocclusionandsmallrightsideinfarction(arrow)PerfusionImagingBOLDtoshowthevisualcortex检查方法显示脑代谢brainmetabolism–ECTSPECTPET–tracer•mostcommonis18FDG，analogueofglucose–MRSSPECTSinglepixelMRS正常影像解剖normalimaginganatomy平片plainfilmCT扫描技术及正常影像解剖techniqueandnormalimaginganatomy以听眦线为基线向上连续扫描9～12层层厚10mm正常影像解剖normalimaginganatomyMRI定位像(topography，scoutimage)T1WIaxialT2WIaxialT1WIcoronalT2WIsagital基本病变表现basicimagingsign颅骨平片–颅骨破坏–颅板增厚–颅板变薄–骨折线depressedskullfractureskulldestructionThinningztableThicknessofskulltable基本病变表现basicimagingsignCT平扫密度改变densitychanges–占位效应masseffect,spaceoccupyingeffect–脑水肿brainedema,cerebraledema–脑积水hydrocephalus–脑萎缩brainatrophy,cerebralatrophy–病灶的强化表现featuresaftercontrastinject基本病变表现basicimagingsignCT–平扫密度改变高密度灶：钙化（肿瘤、血管畸形）、出血–出血的演变低密度灶：坏死、水肿、液体、气体和脂类等密度灶：肿瘤、出血某一阶段混杂密度灶：多种成分病变，多见钙化：正常生理钙化、血管畸形、少枝胶质瘤等等密度isodensity低密度水肿Lowdensity占位效应高密度Highdensity占位效应混杂密度mixeddensity钙化calcification占位效应spaceoccupyingeffect,masseffect–Commondisease肿瘤tumor出血bleeding显著肿胀edema–manifestation中线结构移位displacementofmidlinestructures脑室与脑池移位变形脑室、脑池扩大enlargementofventricleandcistern脑沟变化fuci脑体积的改变enlargementofbrainvolume脑水肿cerebraledema炎症性水肿inflammatoryswelling–感染infection–出血bleeding–挫伤contusion–等血脑通透性增加increasingpermeabilityofBBB–肿瘤tumor–感染infection–等脑积水hydrocephalus原因etiology–脑积液产生和吸收失衡–脑脊液循环通路障碍所致脑室系统异常扩大类型type–交通性脑积水communicativehydrocephalus–阻塞性脑积水obstructivehydrocephalus–代偿性脑积水compensatoryhydrocephalus梗阻性脑积水正常脑压性脑积水Normalpressurehydrocephalus脑萎缩cerebralatrophy描述description–各种原因引起脑组织减少而继发的脑室和蛛网膜下腔扩大分类type–广泛性diffuse–局限性local–皮质cortex–白质whitematter增强扫描特征机制mechanism–血脑屏障通透性增加–异常血管增生引起血流量增加常见类型commontype–均一强化：脑膜瘤、生殖细胞瘤等–环状强化：脑脓肿、脑转移瘤、星形细胞瘤等–斑状强化：血管畸形、炎症等–不规则强化：恶性胶质瘤等–等等密度，均匀强化Isodensity,homogeneousenhancement环形强化Ring-rimenhancement颅骨改变增厚thickness变薄thin破坏destruction增生proliferationgiantcellreparativegranulomatrauma颅骨破坏MRI基本病变表现basicMRIsign与CT类似的表现thesimilarsignastoCT–占位效应–脑积水–脑萎缩信号改变复杂，与CT密度改变不同–长T1、长T2信号：肿瘤、脑梗死、炎症等–脑脊液信号：囊性变、囊肿（FLAIR序列变黑）–短T1、长T2信号：脂肪、黑色素瘤等–无信号：钙化、晚期疤痕组织–血管流空信号：多为无信号MRI基本病变表现水肿edema–T1WI为低信号lowsignal–T2WI为略高信号slightlyhighintensity出血bleeding–信号变化复杂thechangeofsignaliscomplex长T1、长T2病灶，肿瘤水肿edema钙化无信号囊性病灶cysticT2WI高信号MRI基本病变表现增强–环状–均匀–不均匀–脑回状脑内血肿(intracerebralhematoma)CT分期staging–急性期acutestage＜1周高密度hyperdensity周围水肿surroundingedema–吸收期absorptionstage2周～2个月始于3~7天，密度逐渐减低–囊变期cysticchangestage＞2个月水样低密度water-likedensityMRI分期staging–超急性期（Hyperacutehematoma）＜6小时T1WI等信号，T2WI为等信号–急性期（Acutehematoma）7小时～3天T1WI呈等信号，血肿内缘可见低信号强度的硬膜，T2WI呈低信号–亚急性期和慢性期（Subacutehematoma）3天～4周高信号(metahemoglobin)–囊变期（Remotehematoma）≥4周液体信号周围有低信号（hemosiderin)血肿影像学表现ImagingpresentationofhematomaTheevolutionofhematomaHyperacutehematomaCTT1WIT2WICTT2WISubacutetochronichematomaAcutehematomaGRET1WI常见疾病诊断commondiseaseofCNS脑外伤traumaofbrain脑血管病cerebraovasculardisease–脑梗死cerebralinfarction–脑出血cerebralhemorrhage脑肿瘤cerebraltumor脑外伤traumaofbrainCT为首选firstchoice–显示骨折、早期出血好–方便快速–多螺旋可快速形全身检查MRI的适应症indication–CT检查阴性–亚急性期–慢性期平片已少用–CT未普及的地区脑外伤traumaofbrain脑挫裂伤cerebralcontusion脑内血肿intracerebralhematoma硬膜下血肿subduralhematoma硬膜外血肿epiduralhematoma蛛网膜下腔出血subarachnoidhemorrhage脑挫裂伤名词的含义–脑挫伤cerebralcontusion–脑内散在出血灶，静脉淤血、脑血肿和肿胀–脑裂伤lacerationofbrain–伴有脑膜、脑或血管撕裂发病部位location–着力点附近coupsite–着力点对冲部位contrecoup病理pathology–脑水肿–坏死液化–散在小出血点脑挫裂伤CT–低密度病灶内散在斑点状高密度出血灶–边缘模糊ill-definedrim–占位效应masseffectMRI–脑水肿T1WI呈低或等信号T2WI高信号–出血bleeding表现与血肿期龄有关Thereisafocalareaofhaemorrhagiccontusionintherightfrontallobe,withsurroundinglowdensityduetoinfarctionoroedema.Thisisafrequentlocationforacontrecoupinjuryfollowingablowtothebackofthehead.弥漫性轴索损伤diffuseaxonalinjury,DAI其他名称synonymy–剪切伤shearinjury机制mechanism–头受到旋转暴力致大脑绕中轴发生旋转运动白质、灰白质交界区、胼胝体、脑干及小脑等受到剪切力损伤弥漫性轴索断裂、点片状出血和水肿临床clinicalfeatures–伤后意识立即丧失，多数立即死亡–部分持续昏迷，后果严重弥漫性轴索损伤diffuseaxonalinjuryThisimagedemonstratesasmallpetechialhaemorrhageinatypicallocationatthegrey-whitemat