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1、CT AND MRI IMAGING OF NORMAL BRAIN,NORMAL ANATOMY OF BRAIN,Brain is separated from calvarium by three meninges-dura mater,arachnoid membrane and pia mater.Divided into supra tentorial and infra tentorial compartments containing:-Supratentorium:Cerebral hemispheres diencephalonInfratentorium:Brain st
2、em structures cerebellum Each cerebral hemisphere is further divided in to Frontal,Parietal,Temporal and Occipital lobes by fissures,BRAIN ANATOMY,Sagittal surface,Lat vent,Genu,Fornix,Pituitary gland,Mid brain,Pons,Medulla,Cingulate gyrus,Quadrigeminalcistern,Splenium,Colliculi,4th vent,Cerebellum,
3、Thalamus,Sagittal surface,Pineal glandSup.colliculiInf.ColliculiAqueduct of sylviusMidbrainCerebellum4th ventriclePonsOculomotor nInter thalamic commissure,10,9,Inferior surface,Interhemispheric fissure,Temporal lobe,Mammillary bodies,Frontal lobe,Olfactory tract,Optic tract,Pit.stalk,pons,Medulla o
4、blongata,Cerebellum,Vermis,Brain stem structures,Mid brain:divided into Cerebral peduncles and colliculi.Sup colliculi attached to med.Geniculate&Inf to lateral Geniculate bodySurrounded by Peri-mesencephalic cistern.,Pons:divided in to tectum and tegmentum Connects mid brain to medullaMedulla:conti
5、nues as spinal cordContains ascending and descending Spinal tracts,Cerebellum,Divided into two hemispheres by falx cerebelliConnected in the midline by a worm like structure-VermisDivided into I.Anterior lobeii.Middle lobeIii.Flocculo-nodular lobe,Ventricles of brain,Lateral ventricle:-C shaped cavi
6、ty with body in the parietal lobe and extensions in the frontal temporal,occipital lobesConnected to third ventricle by foramen of monro.Third ventricle:-lies b/w two thalami.connected to fourth ventricle by cerebral aqueduct.Fourth ventricle:-lies in the cerebellumCSF Flow:-Lat.vent-foramen of monr
7、o-3rd vent-cerebral aqueduct-4th vent-foramen of magindie and luschka-sub arachnoid space finally absorbed by the arachnoid granulations,Ventricles of brain,Blood supply of the brain,Blood supply of the brain,By Internal Carotid and Vertebral A Internal carotid A:Middle cerebral A Ant cerebral A Pmu
8、nicating A Ant.Choroidal A Vertebral As:-two Vertebral as join to form Basilar A Branches:Ant inf cerebellar A Sup cerebellar A Pontine As&labyrinthine As Post cerebral A,Contd.,Divides into cortical and perforating APerforating As supply Basal ganglia,Thalami,internal capsuleThalamus:-Perforating b
9、r of PCAInternal cap:-Med&lat striate br of MCA,recurrent br of ACA,Ant choroidal AMid brain:-Post.cerebral and Sup cerebellar APons:-Pontine br of Basilar ACerebellum:-Sup.cerebellar A,Ant.inf cerebellar A,Post inf cerebellar AMedulla:-Ant&Post spinal A,PICA,Blood supply of the brain,Red:-MCABlue:-
10、ACAGreen:PCA,Circle of willis,Venous sinuses of brain,Straight sinus,Torculaherophili,Occipital sinus,Transverse sinus,Sup.Sagittal sinus,Inf.Sagittalsinus,Venous sinuses.,Transverse sinus,Straightsinus,sigmoidsinus,Pitutiary gland,ICA,3rd CN,4th CN,6th CN,Sphenoid bone,Vi Vii br Of 5th CN,Axial sec
11、tion,Cingulategyrus,Caudatehead,Pineal gland,Corpus callosum,Lentiform nucleus,trigone,Sup.cerebellar cistern,Int.capsule,Thalamus,Coronal section,CT Technique,Patient is kept in supine position and head is placed in the gantry under the cursors.Axial sections are taken at an angle of 10-13 degree t
12、o the canthomeatal line.Slice thickness:-Posterior fossa:-5mmSupra tentorial structures:-10mmPituitary gland and sellar region:-1-3mm(coronal sections)CONTRAST STUDIES:done by injecting 100 ml of 60%iodinated contrast,contd.,Normal enhancement:Arterial,Axial sections-Topogram,For CT Axial sections a
13、re taken at an angle of10-13degree to the Canthomeatal lineFor MRI sections are parallel to the reference line,CT Brain contd,Normal HU values in NCCT brainGray matter:-+36-42 HUWhite matter:-+26-34 HUCSF:-+4-11HUBone:-+200 to+1000 HUCalcification:-+100 to+220 HUBlood:-+56-80,MRI Imaging,Multiplanar
14、 modlity so sections can be taken in axial,coronal and sagittal planesSlice thickness is same as CT imaging.Routinely applied sequences are T1 Weigheted spin echo T2 Weigheted spin echo Proton density imagesAnatomy of brain is better explained on T1W seq while pathologies are better studied on T2W a
15、nd Proton density sequences.,TISSUE CHARACTERISTICS,Seq Parameters CSF Gray M WhiteM FatT1W short TR Hypo iso hyper hyper short TE T2W short TR hyper iso hypo iso/long TE hypoProton long TR iso Iso iso/hypo hyperdensity short TE blood vessels appear signal void in all the sequences calcification and
16、 fibrous tissue appear hypointense in all sequences,MRI Axial section above foramen magnum,Maxillary sinus,Basilar A.,Medulla,Cerebellar hemisphere,Cisterna magna,Tonsils,Petrous bone,Sphenoid sinus,Nasal cavity,Zygomatic arch,CT Axial section above foramen magnum,Frontal sinus,Sphenoid sinus,Tempor
17、al lobe,Basilar A.,Mastoid cells,Cerebellar hemisphere,Cisterna magna,Medulla,Optic nerve,Pituitary,Sphenoid bone,Temporal bone,Cerebellar tonsils,MRI Axial Section at 4th Ventricle,Lens,Optic nerve,Pituitary,Temporal lobe,Middle cerebellar peduncle,4th Ventricle,Medial rectus,Lateral rectus,Pons,Pe
18、trous temporal bone,Cerebellar hemisphere,CT Axial section at 4th ventricle,Frontal sinus,Frontal bone,Mid.cerebral A,Basilar A.,Pons,4th vent,cerebellum,Mid cerebellarpeduncle,Petrous bone,Temporal horn,Ant.cerebral a,Sella turcica,Vermis,MRI Axial Section above 4th ventricle,Superior oblique muscl
19、e,Pituitary stalk,Upper pons,Superior cerebellar peduncle,Optic chiasma,Ambient cistern,Cerebellar folia,CECT Axial section above 4th ventricle,Frontal lobe,Ant cerebral A.,4TH vent,Cerebellum,Pons,Temporal horn,Infundibulum,Post.cerebral A.,Sphenoid bone,Frontal bone,Frontal sinus,Mid.cerebral A,MR
20、I Axial section at midbrain,Frontal lobe,Interpeduncularcistern,inferi,Vermis,Inferior colliculi,Confluence of sinuses,Ambient cistern,Uncus,Optic tract,Mid cerebralA,Cerebral peduncle,Ant cerebral A,MRI Axial section at 3rd ventricle,Genu of corpuscallosum,Caudate head,Lentiform nuleus,Thalamus,Spl
21、enium of corpus callosum,Frontal horns,Int.capsule,Insula,3rd ventricle,Occipital horns,Optic radiation,CT Axial section at 3rd ventricle,Genu of corpus callosum,Caudate nucleus,Int.capsule,3rd ventricle,Pineal gland,vermis,Occipital lobe,Choroid plexus,Thalamus,Lentiform nucleus,Frontal horn,Perica
22、llosal A,MRI Axial section at mid ventricle,Cingulate gyrus,Body of lateralventricle,Corpus callosum,Central sulcus,Corpus callosum,Inter hemisphericfissure,CT Axial section at mid ventricles,Cingulate gyrus,Body of lateral ventricle,Corpus callosum,Falx cerebri,Occipital horns,Parietal lobe,Corona
23、radiata,Frontal horns,Confluence of Sinuses(torcula),MRI Axial section at centrum semiovale,Inter hemispheric fissure,Centrum semiovale,Occipital lobe,Parietal lobe,Frontal lobe,CT Axial section at centrum semiovale,Falx cerebri,Centrum semiovale,Occipital lobe,Parietal lobe,Frontal lobe,MRI Coronal
24、 section at 3rd ventricle,Frontal horns,Fornix,3rd ventricle,Clivus,Interpeduncularcistern,Insula,Sylvian fissure,Temporal lobe,Parotid gland,Odontoid(dens),MRI Coronal section at suprasellar level,Inter hemispheric fissure,Lat ventricle,Lat.Pterygoid Ms,Nasopharynx,Med.Pterygoid Ms,.,Sylvian fissur
25、e,Sphenoid sinus,Pituitary gland,Optic chiasm,Ant cerebral a,Mid cerebral A,MRI Coronal section at post.ventricle,Parietal lobe,Splenium of corpus callosum,Sup.cerebellar cistern,Tentorium,Choroid plexus,Atria of lateral ventricle,4th ventricle,MRI Sagittal section,Lat vent,Genu,3rd vent,Sphenoid si
26、nus,Nasopharynx,Body of CC,Splenium,Quadrigeminal cistern,Pons,4th vent,Medulla,Cerebellum,Tonsil,Cingulate gyrus,Prepontine cistern,CT Coronal section for Pituitary gland,Patient is kept in prone position in sub mento vertical position,in the head rest of CT tableTopogram is taken in this position
27、and planning is done so that cut sections parallel to the line passing from frontal bone to mentis is takenFor pituitary 1-3mm thick sections are taken in the coronal plane starting from anterior to posterior.,CT Coronal section for Pituitary gland,Lateral vent,Ant.cerebral A,Pituitary gland,Optic c
28、hiasm,Sphenoid sinus,Lat.pterygoid plate,Nasopharynx,Lat.Pterygoid ms,Mid.cranial fossa,CT Coronal section for Pituitary gland,Lat pterygoid plate,Sphenoid sinus,Mid.cerebral a,Ant.cerebral a,Frontal sinus,Internal carotid a,Nasopharynx,Pituitary gland,CT Axial section(bone window),Petrous bone,Mast
29、oid air cells,Carotid canal,Foramen ovale,Sphenoid sinus,Base sphenoid,Eustachian tube,Ext.acoustic canal,Lambdoid suture,Occipital bone,CT Axial sections(bone window),Ear ossicles,Mastoid air cells,cochlea,Int.acoustic meatus,Aditus to antrum,Sq.temporal bone,Facial n canal,Ethmoidal sinus,CT Axial
30、 sections(bone window),Occipital bone,Jugular foramen,Base sphenoid,Sphenoid sinus,Ext.acoustic C,Mastoid air cells,Carotid canal,Greater wing of sphenoid,CT SCAN-Why do it?,Advantages of CT:I.Useful in diagnosis of intracranial bleed in acute head injury ii.Better demarcation of bony pathology iii
31、Easy availability iv.Cost effective v.Less time consuming vi.Easy interpretationsDisadvantages of CT I.Poor demarcation between gray matter and white matter ii.Less effective in very early and very late haemorrage and infarct iii.Radiation hazard,MRI Why do it,Advantages:Multiplanar modalityBetter g
32、ray and white matter differentiation or better spatial resolutionBetter for evaluation of posterior fossa structuresNo radiation hazardDisadvantages:Contraindicated in patients with claustrophobiaContraindicated in patients having aneurysmal clips,metal fillings if these are not MRI compatibleNot useful in evaluation of bony pathologies,calcificationsMovement sensitive,THANK YOU,
