(4.1)-中枢医学影像诊断学

CentralNervoussystemPrefacePlainfilm,CTandMRI

thebenefitsandlimitationsofeachimagingtechniqueshouldbefullyunderstoodPlainskullfilmnotcommonlyrequestedtodayonlyshowthebonystructures,intracranialcalcificationsandpneumocephalusPlainskullfilmPost-anteriorLateralviewCTandMRIcanprovideabundentinformationforclinicaltherapy

NormalCTandMRimagesofbrainSerialtransversesectionofheadprefacemainfourlobes:frontallobeparietallobeoccipitallobetemporallobeNormalimagingFrontallobeParietallobeSuperiorsagittalsinusCentralsulcusNormalimagingFrontalLobeParietallobeCerebralfalxT1WIT2WINormalimagingFrontallobeParietallobeSuperiorsagittalsinusCentralsulcusCerebralfalxFrontalLobeParietallobeSuperiorSagittalsinusCentumsemiovaleFrontalLobeParietallobeSuperiorSagittalsinusCerebralfalxCentrumsemiovaleT1WIT2WIFrontallobeParietallobeOccipitallobeCerebralfalxFrontallobe

OccipitallobeCerebralfalxCorpus

callosumParietallobeLateralventricleTemporallobeOccipitallobeFrontallobeParietallobeFrontallobeCaudatenucleusLateralventricleTemporallobeOccipitalLobeChoroidPlexusthalamusSeptumPellucidumCorpusCallosum(Pars

geniculata

)CorpusCallosum(splenium)thalamusCaudatenucleusLateralsulcusSeptumPellucidumCorpusCallosum(Pars

geniculata

)CorpusCallosum(splenium)ChoroidPlexusSeptumPellucidumampullaofmilkduct

SphenoidalsinusTemporallobeForthventricleCerebellarhemisphereEthmoidalCellulesMedullaoblongataCerebellarhemisphereMedullaoblongataSagittalviewArteriesofthebrainThreemainarteriesvascularizethebrain:theanterior,middleandposteriorcerebralarteriesTheylinkedeachotheratthebaseofthebrainbythecircleofwillisCarotidarteryAnteriorarteryMiddlearteryPosteriorarteryBasalartery

Braintumor

GliomasGliomasarethemostcommonprimarybraintumorsandconstitutemorethan45%ofallintracranialmasslesionsTherearefourmajortypesofgliomas:astrocytoma

oligodendroglioma

ependymoma

medulloblastoma

astrocytomaGradetraditionalusesafourscaleofascendingmalignancyfrom1(benign)to4(malignant)

NewLowgradeor“benign”astrocytoma(gradeI

II,Kernohan1and2)

Anaplastic

astrocytoma(grade

III,Kemohan3)

Glioblastoma

Multiforme(gradeIV,Kemohan4)Astrocytoma(gradeI)BenignmassLocation:whitematterofcerebralhemispheres(oftenexpandadjacentcortex)Age:

20to40yearsoldAstrocytoma(CTgradeI)NonenhancementCT

ill-defined,homogeneous,hypodense/isodensemassCalcificationisseenin15%to20%,cystsarerareCalvarialerosionincorticalmassesisrareEnhancementCTNoenhancementorveryminimalEnhancementshouldraisesuspicionoffocalmalignantdegenerationAstrocytoma(CTgradeI)Astrocytoma(CTgradeI)Astrocytoma(gradeI)

TlW1

HomogeneoushypointensemassMayexpandwhitematterandadjacentcortexAppearscircumscribed,butinfiltratesadjacentbrainCalcificationandcystsuncommonHemorrhageorsurroundingedema(rare)EnhancementTlW1

UsuallynoenhancementEnhancementsuggestsprogressiontohighergradeAstrocytoma(gradeI)T2WlHyperintensemass,homogeneousMayappearcircumscribed,butofteninfiltratesadjacentbrainCalcificationandcystsareuncommonHemorrhageorsurroundingedemaarerareMayexpandadjacentcortexAstrocytoma(MRIgradeI)ContrastAstrocytoma(MRIgradeI)Anaplastic

astrocytoma(gradeⅢ

)

NonenhancementCT

●

heterogenous,mixeddensity

●

calcificationisuncommon,cysticareaiscommon

EnhancementCT

-----enhancestrongly,nonuniformly,irregularrim-enhancementAnaplastic

astrocytoma(gradeⅢ

)plainCTscans

ContrastCTScansAnaplastic

astrocytomas(gradeⅢ

)

MRI●heterogeneoussignalintensitiesonbothT1andT2WI●mixediso-tohypointenseonT1WI●heterogeneoushyperintenseonT2WIAnaplastic

astrocytomas(gradeⅢ

)●

contrastadministration:markedbutirregularperipheralringlikeenhancementAnaplastic

astrocytomas(gradeⅢ

)Glioblastoma

mutiforme(grade

IV)Location:usually:deepwhitematter,

particularythefrontalandtemporallobes,basalganglia,crossthecorpus

callosum(multilobeandbihemispheric)

rare:posteriorfossaGlioblastoma

mutiforme(grade

IV)NonenhancementCTIrregularisodenseorhypodensemassSurroundingedemaismarkedNecrosisorcystiscommonHemorrhageorCalcificationrareEnhancementCT95%havestrong,heterogeneous,irregularrim-enhancementGlioblastoma

mutiforme(grade

IV)MRI●

mixedsignalmassonT1WI●

heterogeneousmassonT2WI●

peripheraledema

isstriking●enhancement:markedbutheterogeneousGlioblastoma

multiforme(grade

IV)Meningioma

accountfor15-25%ofallprimarybraintumors.thepeakoccurrenceis40to60yearsoldIncidenceF/Mis2:1to4:1MeningiomaNonenhancementCTSharplycircumscribedsmoothmassabuttingdura

Hyperdense(70-75%),iso-(25%),hypo-(1-5%)Calcification(20-25%)Necrosis,cysts,hemorrhage(8-23%)

Peritumoral

hypodenseedema(60%)EnhancementCT:>90%enhancehomogeneouslyandintensely

Meningioma(plainCT)

Meningioma(contrastCT)MeningiomaTlWIUsuallyiso-orslightlyhypointensecomparedwithcortexNecrosis,cysts,hemorrhage(8-23%)Besttovisualizegraymatter"buckling"EnhancementTlWI>95%enhancehomogeneously&intenselyDural"tail"(35-80%ofcases):Non-specificMeningiomaT2WI

iso-orslightlyhyperintenseNecrosis,cysts,hemorrhage(8-23%)Bes