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 hemispheresdiencephalon Infratentorium: Brai
2、n stem structures cerebellumEach 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,Quadrigeminal cistern,Splenium,Colliculi,4th vent,Cerebel
3、lum,Thalamus,Sagittal surface,Pineal gland Sup.colliculi Inf. Colliculi Aqueduct of sylvius Midbrain Cerebellum 4th ventricle Pons Oculomotor n Inter thalamic commissure,10,9,Inferior surface,Interhemispheric fissure,Temporal lobe,Mammillary bodies,Frontal lobe,Olfactory tract,Optic tract,Pit. stalk
4、,pons,Medulla oblongata,Cerebellum,Vermis,Brain stem structures,Mid brain: divided into Cere bral peduncles and colliculi. Sup colliculi attached to med. Geniculate & Inf to lateral Geniculate body Surrounded by Peri- mesencephalic cistern.,Pons: divided in to tectum andtegmentum Connects mid brain
5、to medulla Medulla:continues as spinal cord Contains ascending and descending Spinal tracts,Cerebellum,Divided into two hemispheres by falx cerebelli Connected in the midline by a worm like structure -Vermis Divided into I. Anterior lobe ii. Middle lobe Iii. Flocculo-nodular lobe,Ventricles of brain
6、,Lateral ventricle:-C shaped cavity with body in the parietal lobe and extensions in the frontal temporal,occipital lobes Connected 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 cerebell
7、um CSF Flow:-Lat.vent-foramen of monro-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 AInternal carotid A:
8、 Middle cerebral AAnt cerebral APost. communicating A Ant. Choroidal A Vertebral As:- two Vertebral as join to form Basilar ABranches: Ant inf cerebellar ASup cerebellar APontine As & labyrinthine AsPost cerebral A,Contd.,Divides into cortical and perforating A Perforating As supply Basal ganglia,Th
9、alami, internal capsule Thalamus:-Perforating br of PCA Internal cap:-Med& lat striate br of MCA,recurrent br of ACA ,Ant choroidal A Mid brain:-Post.cerebral and Sup cerebellar A Pons:-Pontine br of Basilar A Cerebellum:-Sup.cerebellar A,Ant.inf cerebellar A,Post inf cerebellar A Medulla:-Ant &Post
10、 spinal A, PICA,Blood supply of the brain,Red:- MCA Blue:-ACA Green: PCA,Circle of willis,Venous sinuses of brain,Straight sinus,Torcula herophili,Occipital sinus,Transversesinus,Sup. Sagittal sinus,Inf. Sagittal sinus,Venous sinuses,Transverse sinus,Straight sinus,sigmoid sinus,Pitutiary gland,ICA,
11、3rd CN,4th CN,6th CN,Sphenoid bone,Vi Vii br Of 5th CN,Axial section,Cingulate gyrus,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 t
12、he cursors.Axial sections are taken at an angle of 10-13 degree to the canthomeatal line. Slice thickness:- Posterior fossa:-5mm Supra tentorial structures:-10mm Pituitary gland and sellar region:-1- 3mm (coronal sections ) CONTRAST STUDIES: done by injecting 100 ml of 60%iodinated contrast,contd,No
13、rmal enhancement :Arterial ,Axial sections-Topogram,For CT Axial sections are taken at an angle of 10-13degree to the Canthomeatal lineFor MRI sections areparallel to the referenceline,CT Brain contd,Normal HU values in NCCT brain Gray matter:- +36-42 HU White matter:- +26-34 HU CSF:- +4-11HU Bone:-
14、 +200 to +1000 HU Calcification:- +100 to +220 HU Blood:-+56-80,MRI Imaging,Multiplanar modlity so sections can be taken in axial ,coronal and sagittal planes Slice thickness is same as CT imaging. Routinely applied sequences areT1 Weigheted spin echoT2 Weigheted spin echoProton density images Anato
15、my of brain is better explained on T1W seq while pathologies are better studied on T2W and Proton density sequences.,TISSUE CHARACTERISTICS,Seq Parameters CSF Gray M WhiteM Fat T1W short TR Hypo iso hyper hypershort TE T2W short TR hyper iso hypo iso / long TE hypo Proton long TR iso Iso iso/hypo hy
16、per density short TE blood vessels appear signal void in all the sequencescalcification and 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 cavi
17、ty,Zygomatic arch,CT Axial section above foramen magnum,Frontal sinus,Sphenoid sinus,Temporal 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,
18、Temporal lobe,Middle cerebellar peduncle,4th Ventricle,Medial rectus,Lateral rectus,Pons,Petrous temporal bone,Cerebellar hemisphere,CT Axial section at 4th ventricle,Frontal sinus,Frontal bone,Mid.cerebral A,Basilar A.,Pons,4th vent,cerebellum,Mid cerebellar peduncle,Petrous bone,Temporal horn,Ant.
19、cerebral a,Sella turcica,Vermis,MRI Axial Section above 4th ventricle,Superior oblique muscle,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 h
20、orn,Infundibulum,Post.cerebral A.,Sphenoid bone,Frontal bone,Frontal sinus,Mid.cerebral A,MRI Axial section at midbrain,Frontal lobe,Interpeduncular cistern,inferi,Vermis,Inferior colliculi,Confluence of sinuses,Ambient cistern,Uncus,Optic tract,Mid cerebralA,Cerebralpeduncle,Ant cerebral A,MRI Axia
21、l section at 3rd ventricle,Genu of corpus callosum,Caudate head,Lentiform nuleus,Thalamus,Splenium 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,Pin
22、eal gland,vermis,Occipital lobe,Choroid plexus,Thalamus,Lentiform nucleus,Frontal horn,Pericallosal A,MRI Axial section at mid ventricle,Cingulate gyrus,Body of lateral ventricle,Corpus callosum,Central sulcus,Corpus callosum,Inter hemispheric fissure,CT Axial section at mid ventricles,Cingulate gyr
23、us,Body of lateralventricle,Corpus callosum,Falx cerebri,Occipital horns,Parietal lobe,Corona 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
24、 semiovale,Falx cerebri,Centrumsemiovale,Occipital lobe,Parietal lobe,Frontal lobe,MRI Coronal section at 3rd ventricle,Frontal horns,Fornix,3rd ventricle,Clivus,Interpeduncular cistern,Insula,Sylvian fissure,Temporal lobe,Parotid gland,Odontoid (dens),MRI Coronal section at suprasellar level,Inter
25、hemisphericfissure,Lat ventricle,Lat.Pterygoid Ms,Nasopharynx,Med.Pterygoid Ms,.,Sylvian fissure,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,
26、Atria of lateral ventricle,4th ventricle,MRI Sagittal section,Lat vent,Genu,3rd vent,Sphenoid sinus,Nasopharynx,Body of CC,Splenium,Quadrigeminalcistern,Pons,4th vent,Medulla,Cerebellum,Tonsil,Cingulate gyrus,Prepontine cistern,CT Coronal section for Pituitary gland,Patient is kept in prone position
27、 in sub mento vertical position,in the head rest of CT table Topogram is taken in this position and planning is done so that cut sections parallel to the line passing from frontal bone to mentis is taken For pituitary 1-3mm thick sections are taken in the coronal plane starting from anterior to post
28、erior.,CT Coronal section for Pituitary gland,Lateral vent,Ant.cerebral A,Pituitarygland,Optic chiasm,Sphenoid sinus,Lat.pterygoid plate,Nasopharynx,Lat. Pterygoidms,Mid.cranial fossa,CT Coronal section for Pituitary gland,Lat pterygoid plate,Sphenoid sinus,Mid.cerebral a,Ant.cerebral a,Frontal sinu
29、s,Internal carotid a,Nasopharynx,Pituitary gland,CT Axial section (bone window),Petrous bone,Mastoid air cells,Carotid canal,Foramen ovale,Sphenoid sinus,Base sphenoid,Eustachiantube,Ext.acoustic canal,Lambdoid suture,Occipital bone,CT Axial sections(bone window),Ear ossicles,Mastoid air cells,cochl
30、ea,Int. acoustic meatus,Aditus to antrum,Sq.temporalbone,Facial n canal,Ethmoidal sinus,CT Axial 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
31、diagnosis of intracranial bleed in acute head injuryii. Better demarcation of bony pathologyiii Easy availabilityiv. Cost effectivev. Less time consumingvi. Easy interpretations Disadvantages of CTI. Poor demarcation between gray matter and white matterii. Less effective in very early and very late
32、haemorrage and infarctiii. Radiation hazard,MRI Why do it,Advantages: Multiplanar modality Better gray and white matter differentiation or better spatial resolution Better for evaluation of posterior fossa structures No radiation hazard Disadvantages: Contraindicated in patients with claustrophobia Contraindicated in patients having aneurysmal clips,metal fillings if these are not MRI compatible Not useful in evaluation of bony pathologies, calcifications Movement sensitive,THANK YOU,
