临床神经病学课件：中枢神经系统影像学

CentralNervousSystem

中枢神经系统影像学

Imaging

Modalities

Radiography(plainfilm)

ComputedTomography(CT)Myelography&CTmyelography

MagneticResonanceImaging(MRI)NeurosonographyDigitalsubtractionangiography(DSA)Plainfilm

(radiography)适应症：头颅外伤、头颅先天畸形和颅骨疾病A-PPositionLateralPositionComputedTomographyPlainscan(includingposteriorfossacuts)适用于：颅脑外伤、脑出血、脑梗塞等Enhancedscan（includingCTA）适用于：血管相关性病变、肿瘤性病变、感染性疾病（如脑膜炎、脑脓肿）Perfusionscan适用于：超急性期脑梗塞的诊断、肿瘤病变性质的判断CTmyelographyRoutineAxialHeadPosteriorFossaCutMRIPlainscan(T1WI,T2WI,T2-Flair,DWI,MRS,MRA,MRV;Axial,Coronal,Sagittal)Enhancedscan（includingceMRAandPerfusion）ContrastMedium:Gd-DTPA(二乙烯三胺五醋酸钆)NormalmanifestationofCTandMRIImaging解剖结构CT（密度）MR（信号）T1WIT2WI灰质（皮质）略高略低略高白质（髓质）略低略高略低脑脊液低低高骨质、钙化灶高低低血管等或局部高低低NormalCTandMRImagingAnatomyNormalCTandMRImagingAnatomyNormalCTandMRImagingAnatomyNormalCTandMRImagingAnatomyNormalCTandMRImagingAnatomyMRI—multiplanarimgaingMR的伪影MR难以观察钙化巨细胞病毒宫内感染Thephysiologicallyenhancedstructures

PituitaryglandandstalkDuralstructureArterialstructuresChoroidplexuswithinventriclesEnhancementImagingofCT

影像学检查方法的选择颅脑外伤－－急诊CT可疑脑卒中－－急诊CT可疑脑肿瘤－－MR可疑中枢神经系统感染－－MR神经系统的基本病理改变脑血管病变肿瘤影像学特征密度/信号改变占位效应周围水肿强化特点♦血管造影（DSA）是诊断颅内动脉瘤、血管畸形的首选方法

♦高质量的CTA，MRA可以部分代替DSA血管病变血管

造影

DSACTA动静脉畸形（AVM）脑血管意外Stroke脑梗死Infarction脑出血Hemorrhage：脑实质、脑室、蛛网膜下腔CerebralInfarction

(PlainScan)病变时期CTMRI急性期（<24h）50-60%无阳性发现（<8h）；低密度改变，占位效应不明显T1WI略低，T2WI略高信号；DWI明显高信号亚急性期（24h～4w）楔形或扇形低密度区，占位效应，边缘渐变清晰第2~3w出现“模糊效应”T1WI低，T2WI高信号，形态和占位效应同CT慢性期（4w～2m）病变区域密度下降（脑脊液密度），体积缩小，边缘清晰，相邻脑沟、脑室扩大病灶信号特征同脑脊液AcutestageSubacutestageChronicstageT2WIDWI早期诊断脑梗塞最敏感的方法：扩散加权成像DWI（Diffusion-weightedimaging）出血性脑梗塞血管再通后或侧支循环建立后，多发生于亚急性期，好发于基底节区和皮质Subacutestage：enhancementCTimagingrevealsgyralenhancementCerebralInfarction

(EnhancementScan)T1WIfollowingintravenousgadoliniumT2WIGyralandsubcorticalenhancementofCICTperfursionofbrain腔隙性脑梗塞

Lacunainfarction发病部位：基底节、丘脑、放射冠、脑干、小脑病灶大小：<1.5cm

检查方法：MRI敏感性高于CT脑出血

Hemorrhage诊断急性脑内血肿（Hematoma）首选方法：CT成分

密度/信号演变体积改变CT急性期血浆＋血红蛋白高密度大→小融冰征亚急性期血红蛋白破坏纤维蛋白溶解等密度慢性期脑脊液密度低密度MR超急、急性期含氧hb→脱氧hbT1等T2高→T1等T2低大→小亚急性期正铁hbT1等T2低（周边高）→T1高T2高慢性期囊腔＋含铁血黄素T1低T2高有T1低T2低环ImagingModalities:CTandMRIAcuteHematoma（0～2天）T1WI等或低信号，T2WI高信号低信号SubacuteHematoma（2～14天）：T1WI高信号，T2WI低信号高信号

ChronicHematomaT1WI低信号；T2WI中央高信号，周围是低信号的含铁血黄素环TraumaofCNSFracture:Linearanddepressed,PneumocephalusIntracerebralHematomaExtracerebralHematomaEpiduralhematomaSubduralhematomaSubarachnoidhematomaFractureDepressedfractureLinearfracturePneumocephalusDuraandDuralStructuresDuralmaterArachnoidmembrane

PiamaterEpiduralhematomaEpiduralhematoma软组织窗骨窗EpiduralhematomaSubduralhematomaSubduralhematomaSubduralhematomaSubarachnoidhematoma颅内肿瘤

Intracranialneoplasms密度/信号改变占位效应周围水肿增强扫描明确肿瘤范围、数目和性质。Howtodifferentiateintra-andextra-axialtumorMeningeoma大脑镰脑膜瘤Glioma大脑半球星形细胞瘤II级脑转移瘤好发部位：灰白质交界处瘤周水肿增强扫描明显强