中樞神經(jīng)系統(tǒng)影像學(xué)表現(xiàn)

Centralnervoussystem

Generalview1.conventionalx-rayexamination:2.modernmodalities:computerappearsaround

1970s.CTin1969.MRI(magneticresonanceimaging).DSA(digitalsubtractionangiography)Conventionalx-rayexamination:..Plainfilm.Headandspinalcolumnfilm(Includingfrontandlateralview)

ExaminationModalityiesFrontviewLateralview..Angiography

internalcarotidarteriography

vertebralarteriography..Myelography

2.DSA(digitalsubtractionangiography)

IADSA(intrarterialDSA)IVDSA(intravenousDSA)DSAinternalcarotidarteriographyvertebralarteriographyAneurysmEmbolization

3.CT(computedtomography)...Plainscan...Contrast–enhancedscan

...Post–contrastexaminationscan

ScoutviewAxialviewCoronalviewPlainscanContrast-enhancedscanScoutviewAxialview

4.MRI(magneticresonanceimaging)...HeadMRI...SpinalMRI

BrainMRIT1WIT2WINormalbrainaxialviews(onlytwomainplanes)Pons腦橋

cerebellum小腦vermis小腦蚓部

Suprasellarcistern鞍上池Posteriorclinoidprocess后床突Ambientcistern環(huán)池AnteriorhornoflateralventricleHead/caputofcaudatenucleusthalamuslenticularnucleus(put-amenandglobuspallidus)ExternalcapsulePosteriorlimbofinternalcapsuleAnteriorlimbofinternalcapsuleCalcificationofpinealbodyGenuofcorpuscallosumGenuofinternalcapsuleTrigoneoflateralventricleAbnormalappearanceofheadCT1.Changeofdensityhyperdensityhypodensityisodensity2.Enhancementnoenhancementhomogeneousenhancementinhomogeneousenhancementannularenhancement3.Morphologychangenote:location,size,number,border,middlestructure,surroundingtissue,bonestructure.CommonDiseasesofCNSTumorofCNS..primary:glioma,meningioma,pituitaryadenoma,craniopharyngioma,acousticneuroma,pinealoma..secondary:metastatictumorGlioma(thecommonestintracranialtumor)

…4types:.astrocytoma(commonest).oligodendroglioma.ependymoma.medulloblastoma

Astrocytoma(incidence:45percentofintracranialtumor)Grading

Kernohan’s:

I(benign)toIV(malignant).WHO-----3-tieredsystemlowgradeorbenign,anaplastic,glioblastomamultiform

Thenewgradingscalecorrelatedwithkernohan’sgrading:WHOkernohan’slowgradeorbenign---------gradeI,??anaplastic---------grade???glioblastomamultiform---------gradeIVAppearance.location:whitematter:adult(cerebralhemisphere---supratentorial),children(cerebellum---infratentorial).CTappearance:

*loworbenign(astrocytoma--grade

I,??):

1.Onplainscan:.lowill-defineddensitylesion(18-24HU)(necrosis,cystformation,hemorrhage,calcification).Edema(rare).Slightmasseffect2.OncontrastenhancedCT,.astrocytoma(grade

I)---noorslightenhancement

.astrocytoma(grade

II)---enhancementpatternresemblestogradeI(noenhancement)orIII,IV(stronginhomogenousenhancement)*astrocytoma(grade

III,IV

)

1.Plainscan.well-definedmixed-densitylesion(cystformation,necrosisandhemorrhagecalcification).perifocaledema..Severemasseffect2.OnenhancementCTusuallystrongenhancedinhomogenously

Astrocytoma

plainscancontrast-enhancedscan

meningioma

Generalview:

ArachnoidgranulationLinkedwithduralmatterLocation:

Parasagittalregion,falx,convexity,

olfactorygroove,tuberclesellae,sphenoidridge.Thefirstthreearethemostcommonplaces.CTappearance

Typicalfindings

1.Onplainscan.Well-definedandhomogenoushighdensity(74.4%)massabutingduramatteratanobtuseangle

{calcification(10-20%),hemorrhage,necrosisandcystformation(usual)}.surroundingedema(61.3%).masseffect.thickeningordestructionofadjacentbone

2.OncontrastenhacedCT.strongandhomogenousenhancement

Meningiomaonplainscan(petrosa)Meningiomaoncontrastenancedscan(petrosa)Atypicalappearance(learnyourself)

1.Multiplelesions2.Resembletointracerebraltumor3.Inhomogenousdensitymass4.Cysticcomponentdominatedmass5.Totallowdensitywithinhomogenouscontrast6.Ossifiedmeningioma7.Hemorrhageinsidethetumor8.Ringenhancement9.Nodulesontheinnersurfaceofthecystwall

MetastatictumorofbrainGeneralview:

CTfindings1.Plainscan.Mutiplenodesormasseswithvariousdensityonthewhiteandgraymatterjunction(hemorrhage,necrosis,cysticcomponent,calcification).Strikingedemaaroundtumor.Masseffect2.ContrastenhancedCT.Variousenhancementpatterns(ring,nodularenhancement)

MetastatictumorinrightparietalandoccipitallobeonplainscanMetastatictumorinrightparietalandoccipitallobeonCTplainscanMetastatictumorinrightparietalandoccipitallobeoncontrastenhancedCTMetastatictumorinrightparietalandoccipitallobeoncontrast-enhancedCTCraniocerebralTrauma.CTisexcellentfordetectingdetectingandelvaluatingthetraumaanditsprognosis..Usuallythecraniocerebraltraumacanclassifiedinto3types,andtheymayappearcoincidentally:

traumaofscalp(haematoma,laceration)galeaaponeurotica

traumaofskulltraumaofintracranialtissuesEpiduralHaematoma(EDH)

PathologyAcceleratingmovement–skullfracture---MMAandoritsbranchestearorrupture---Venoussinus,diploicvein

CTfindingsAcuteEDH

...Biconvexorlentiform–shapedshadowwithuniformhighdensity(sometimesmixeddensity)underinnertableoftheskull.

…AdjacentbraintissueiscompressedandflattenedandEDHhastheclearandsharpsurfacewithnearbybrain

…Doesnotcrossingthesuture

…Withslightoccupyingeffect(adjoiningtissues,middlelinestructures,ventricles,cisterns)

…AccompanyingwithskullfracturePlainscan:acuteepiduralhaematomaPlainscan:acuteepiduralhaematomaPlainscan:acuteepiduralhaematomaSubduralhematoma

（sdh）PathologyDeceleratingmovement—veinorarterioleorbridgingveinontheoppositesiteofthetrauma/bridgingvein(contre-coupinjury,thehedgeposition)---accompanyingwithbraincontusionandlaceration

CTfindingsAcuteSDH

…crescenthomogenoushighdensity(sometimeshypo-oriso-desityduetoanemiaorCSFmix,sometimesmixeddensitybecauseofCSFmixingandserumextrusionduringclotcontraction,)underinnertableoftheskull.Itcanspreaddiffuselyevenovertheaffectedhemisphere.

…Crossthesuture

…severemasseffect(lateralventriclesandadjacentbraincompression/displacement,shiftofmidlinestructure)

…Accompanyingwithbrainlacerationandcontusion,orintracerebralhaematomaPlainscan:acutesubduralhaematomaPlainscan:acutesubduralhaematoma

SubacuteandchronicSDH(learnyourselfafterclass)ONplainscan

…crescentorbiconvex-shapedshadowwithhyper-，

hypo-，iso-ormixeddensity.(sometimesitpresentsyouwithupperpartlowdensityandlowerparthigh-densityowetoclotprecipitation.)calcification.…cancrossthesuture…obviousmasseffect(lateralventriclesandadjacentbraincompression/displacement,shiftofmidlinestructure)oncontrast-ehancedCT

…enhancedbloodvesselsofbrainsurfaceisdisplacedfromtheinnertableofskull,

…contrastedSDHs’capsule(capillary-richmembrane)

Plainscan:subacutesubduralhaematomaContrast-enhancedscan:subacutesubduralhaematomasubarachnoidhemorrhage

(SAH)Generalviewtraumaticspontaneous(aneurysm)

Pathology.non-bacterialmeningitis(oxyhemoglobin).cerebralspasmbrainedema,encephalomalacia,

.Hydrocephalus(arachnoidgranulationblock)CTappearance.increaseddensityinsulciandCSFcisterns(interhemisphericcistern).Cerebralinfarction.Hydrocephalus(latestage)AcutesubarachnoidhemorrhagecerebralcontusionandlacerationGeneralview.Cerebralcontusionreferstoedema,swelling,smallhemorrhageofthebraincortexanddeepbrain.Cerebrallacerationmeansthebloodvesseltearinbrainandpiamater.Pathlogy.earlystage(withinseveraldays)hemorrhage,swellingandedema,necrosis.middlestage(severaldays—severalweeks)liquefactionofnecrosisareasandreplacedbyscartissues.Smalllesionissubstitutedbygliocytesandgranulationtissueforlargeone..latestage(severalweeks–severalyears)smalllesionisrepairedbyscartissues,largelesionisreplacedbycystaccompanyingwithatrophyofadjacentbrainandmeningesthickening/adhesionCTfindings1.Focalandill-definedlowdensity.Sometimesverywide.Itrecoverstonormalbraindensityafterseveraldaysorseveralweeks..Ifitbecomeslowerthatmeansncephalomalaciaispresent..Cystformationwilloccurinthelatestage.2.Smallhemorrhage.varyinsizeandshape..Absorbfrom3-7daysafterdamage,andbecomeslowdensity1-2monthslater3.Masseffect(cerebralventriclesandadjacentbraincompression/displacement,shiftofmidlinestructure,brainhernia)4.SometimesAccompanyingwithsubarachnoidhematoma,intracranialorextrocranialhematoma,skullfracture.5.Latestage,localbrainatrophyoccurs(sulibecomeswide,braincisternsenlarges)

AcutebraincontusionandlacerationBrainvasculardiseasesIntracerebralhemorrhage1.Generalview:commonreasons(hypertension,aneurysm,malformationofcerebralbloodvessels,post-infarction)thefirstiscommonestone.Basalnucleusareaisthecommonsite.2.CTfindings(basedonthehematoma’sage)

AcutestageAbsorbedstageCystformationstageDuration<1week2weeks–2months>2monthsShapeanddensityroundorirregular-shaped,Homogenoushighdensity(60-80HU)Hematomaisabsorbedfromperipheralregiontocentralregionwithill-definedmarginandformsaiso-orlowdensityareaat4thweekafteronsetLowdensitySmalllesionisreplacedbygliacytesandneroglia,bigonewillformacystwithCSFPerifocaledema

withDecreasedgraduallynoneMasseffectwithDecreasedgraduallynoneEnhancem-entSeldomdoneRoundenhancem-entnoneIntracerebralhemorrhageIntracerebralhemorrhageIntracerebralhemorrhageCerebralinfarction

GeneralviewItcanbedividedinto3partterns:theischemic,thehemorrhagic,thelacunar.Thecommonreasonsarecerebralarteryembolismasaresultofatherosclerosis

Ischemicinfarction

CTfindings

..lowdensityareas:..nopositivefoundingswithin24hours.Orill-definedlowdensity...inearlystagewestillcanfindsomesigns:a.hyperdense(hyperattenuating)arterysign:increaseddensityofaffectedarterydueduetotheintraluminalthrombus,usuallyhappensinmiddlecerebralartery(MCA).

b.insularribbonsign:IntheearlyphaseofMCAembolism,thegray-whitematerinterfacelossintheareaofinsularlobe,claustrumandextremecapsule...after24hours,alowdensityareaconformsinshapetotheaffectedarterydistibutioninvolvinggrayandwhitematter..2-3weekslater,foggingeffectappearsbecauseofmacrophageinvasionandperifocaledemaloss.thelesionpresentyouwithisodensity...i