IMAGING OF THEIMAGING OF THE

BRAIN BRAIN

BRAINBRAINANATOMY

IMAGING MODALITIES

ANATOMY ANATOMY (DEVELOPMENT)(DEVELOPMENT)

The beginning is the union of a The beginning is the union of a sperm with an ovum to form the sperm with an ovum to form the zygotezygote..

Then this single celled zygote Then this single celled zygote divides to become the multicellular divides to become the multicellular embryonic plate.embryonic plate.

The cells of this plate are organized The cells of this plate are organized into 3 layers: ectoderm, endoderm & into 3 layers: ectoderm, endoderm & an intervening mesoderm.an intervening mesoderm.

Thickening in the middle of the Thickening in the middle of the ectoderm forms the neural plate, ectoderm forms the neural plate, folding of the neural plate forms the folding of the neural plate forms the neural tube.neural tube.

The cranial part of the neural tube The cranial part of the neural tube becomes the brain while the caudal becomes the brain while the caudal part becomes the spinal cord.part becomes the spinal cord.

The cranial part of the neural tube dilates into 3 primary vesicles : the forebrain The cranial part of the neural tube dilates into 3 primary vesicles : the forebrain (prosencephalon) , the midbrain (mesencephalon) & the hindbrain (rhombencephalon).(prosencephalon) , the midbrain (mesencephalon) & the hindbrain (rhombencephalon).

From these 3 vesicles, 5 secondary vesicles develop.From these 3 vesicles, 5 secondary vesicles develop.

Adult brain is formed of:Adult brain is formed of: 1- Cerebral hemispheres.1- Cerebral hemispheres.

2- Brain stem.2- Brain stem.

3- Cerebellum.3- Cerebellum.

All are covered with meninges, floating in a fluid (CSF) & enclosing All are covered with meninges, floating in a fluid (CSF) & enclosing

a cavity ( ventricular system).a cavity ( ventricular system).

Brain is contained in a bony box called: neurocranium.Brain is contained in a bony box called: neurocranium.

Cerebral hemispheresCerebral hemispheres

♥♥ The brain is formed of 2 cerebral The brain is formed of 2 cerebral hemispheres Right & Left separated hemispheres Right & Left separated by the interhemispheric fissure, but by the interhemispheric fissure, but again connected to each other again connected to each other through through commissures:commissures:

1- Corpus callosum (rostrum,1- Corpus callosum (rostrum, genu, body & splenium).genu, body & splenium). 2- Anterior commissure.2- Anterior commissure. 3- Posterior commissure.3- Posterior commissure. 4- Hippocampal commissure.4- Hippocampal commissure.

♥♥ Each hemisphere is formed of an outer Each hemisphere is formed of an outer layer of grey matter (cerebral cortex) layer of grey matter (cerebral cortex) which is formed of prominent which is formed of prominent gyri && interveningintervening sulci, and an inner layer, and an inner layer of white matter ( centrum semiovale of white matter ( centrum semiovale & internal capsule).& internal capsule).

♥♥ Islands of grey matter are present inside Islands of grey matter are present inside the white matter: basal gangliathe white matter: basal ganglia

(caudate, putamen & globus pallidus).(caudate, putamen & globus pallidus).

BASAL GANGLIABASAL GANGLIA

♣♣ Islands of neural cell bodies (grey matter) Islands of neural cell bodies (grey matter) within the white matter.within the white matter.

♣♣ Formed of:Formed of: 1- Caudate nucleus (head, body & tail).1- Caudate nucleus (head, body & tail). 2- Putamen.2- Putamen. 3- Globus pallidus.3- Globus pallidus. 4- Amygdaloid nuclear complex (amygdala).4- Amygdaloid nuclear complex (amygdala). 5- Claustrum.5- Claustrum.

Globus pallidus + Putamen = Lentiform Globus pallidus + Putamen = Lentiform nucleus.nucleus.

Caudate + Putamen = Striatum.Caudate + Putamen = Striatum.

Certain sulci divide each hemisphere into lobes:Certain sulci divide each hemisphere into lobes: 1- The central sulcus separates the frontal (anteriorly) and the parietal1- The central sulcus separates the frontal (anteriorly) and the parietal (posteriorly) lobes.(posteriorly) lobes. 2- The lateral sulcus (Sylvian fissure) separates the frontal & parietal lobes2- The lateral sulcus (Sylvian fissure) separates the frontal & parietal lobes superiorly from the temporal lobe inferiorly.superiorly from the temporal lobe inferiorly. 3- The parieto-occipital sulcus marks the posterior boundary of the parietal3- The parieto-occipital sulcus marks the posterior boundary of the parietal lobe & the anterior boundary of the occipital lobe.lobe & the anterior boundary of the occipital lobe. ♥ ♥ The insular lobe is buried within the lateral sulcus under opercula The insular lobe is buried within the lateral sulcus under opercula from the frontal, parietal & temporal lobes.from the frontal, parietal & temporal lobes. ♥ ♥ the limbic lobe is a C-shaped structure that lies along & above the the limbic lobe is a C-shaped structure that lies along & above the corpus callosum on the medial surface of the cerebral hemisphere.corpus callosum on the medial surface of the cerebral hemisphere. The cavity within the cerebral hemisphere is The cavity within the cerebral hemisphere is the lateral ventriclethe lateral ventricle..

THE DIENCEPHALON is a part of the brain that is distinct embryologically THE DIENCEPHALON is a part of the brain that is distinct embryologically however not separable anatomically from telencephalon (cerebral hemispheres).however not separable anatomically from telencephalon (cerebral hemispheres).

It is formed of: thalamus, epithalamus, hypothalamus & subthalamus.It is formed of: thalamus, epithalamus, hypothalamus & subthalamus. The cavity within the diencephalon is the third ventricle.The cavity within the diencephalon is the third ventricle.

CerebellumCerebellum A small structure growing out from the posterior aspect of the brain & occupies the A small structure growing out from the posterior aspect of the brain & occupies the

posterior cranial fossa.posterior cranial fossa. It is formed of 2 cerebellar hemispheres connected in the midline by It is formed of 2 cerebellar hemispheres connected in the midline by the vermis.the vermis. It forms the roof of the forth ventricle and connected to the brain stem by 3 cerebellar It forms the roof of the forth ventricle and connected to the brain stem by 3 cerebellar

peduncles (superior, middle & inferior).peduncles (superior, middle & inferior). It is roofed by the tentorium cerebelli while a small dural reflection invests the groove It is roofed by the tentorium cerebelli while a small dural reflection invests the groove

between its hemispheres called falx cerebelli.between its hemispheres called falx cerebelli. The narrowest subdivisions of the cerebellar cortex are called The narrowest subdivisions of the cerebellar cortex are called foliafolia..

Parts of the cerebellum:Parts of the cerebellum: 2 hemispheres & a vermis.2 hemispheres & a vermis.

Hemisphere:Hemisphere:

1- Anterior lobe: anterior to the primary fissure.1- Anterior lobe: anterior to the primary fissure.

2- Posterior lobe: between the primary fissure & postero-lateral 2- Posterior lobe: between the primary fissure & postero-lateral

fissure.fissure.

3- Flocconodular lobe.3- Flocconodular lobe.

Brain stemBrain stem

Connects the cerebral hemispheres & cerebellum to the spinal cord.Connects the cerebral hemispheres & cerebellum to the spinal cord. It is formed of: It is formed of:

1-Midbrin.1-Midbrin. 2-Pons.2-Pons. 3-Medulla oblongata.3-Medulla oblongata.

Ventral surfaceVentral surface ::

MIDBRAINMIDBRAIN - - 2 cerebral peduncle.2 cerebral peduncle. - interpeduncular fossa.- interpeduncular fossa. ♥ ♥ The posterior perforated substance lies in the The posterior perforated substance lies in the interpeduncular fossa, it is penetrated by interpeduncular fossa, it is penetrated by branches of the posterior cerebral & posterior branches of the posterior cerebral & posterior communicating arteries.communicating arteries. ♥ ♥ Oculomotor nerve CN III emerges from theOculomotor nerve CN III emerges from the ventral surface.ventral surface.

PONSPONS The superior pontine sulcus separates pons fromThe superior pontine sulcus separates pons from

midbrain, while the inferior pontine sulcusmidbrain, while the inferior pontine sulcus separates it from medulla oblongata.separates it from medulla oblongata. Base of the pons.Base of the pons. Cranial nerves that emerge from its ventral Cranial nerves that emerge from its ventral surface are:surface are: 1- Trigeminal nerve CN V.1- Trigeminal nerve CN V. 2- Abducent nerve CN VI.2- Abducent nerve CN VI. 3- Facial nerve CN VII.3- Facial nerve CN VII. 4- Vestibulocochlear nerve CN VIII.4- Vestibulocochlear nerve CN VIII.

MEDULLA OBLONGATAMEDULLA OBLONGATA Pyramids.Pyramids. Olives.Olives. Cranial nerves:Cranial nerves: 1- Glossopharyngeal nerve CN IX.1- Glossopharyngeal nerve CN IX. 2- Vagal nerve CN X.2- Vagal nerve CN X. 3- Accessory nerve CN XI.3- Accessory nerve CN XI. 4- Hypoglossal nerve CN XII. 4- Hypoglossal nerve CN XII.

Dorsal surface:Dorsal surface:MIDBRAINMIDBRAIN - Superior colliculus.- Superior colliculus.

- Brachium of the superior colliculus.- Brachium of the superior colliculus. - Inferior colliculus.- Inferior colliculus. - Brachium of the inferior colliculus.- Brachium of the inferior colliculus. superior & inferior colliculi form the quadrigeminal superior & inferior colliculi form the quadrigeminal

plate.plate. *The trochlear nerve CN IV emerges from the *The trochlear nerve CN IV emerges from the dorsal surface.dorsal surface.

PONSPONS

Upper part of rhomboid fossa:Upper part of rhomboid fossa: - Median eminence.- Median eminence. - Facial colliculus.- Facial colliculus. - Sulcus limitans.- Sulcus limitans.

-Vestibular area.-Vestibular area. -- Striae medullais.Striae medullais.

MEDULLA OBLONGATAMEDULLA OBLONGATA Lower part of the rhomboid fossa:Lower part of the rhomboid fossa: - Vagal trigone.- Vagal trigone. - Hypoglossal trigone.- Hypoglossal trigone. - Sulcus limitans.- Sulcus limitans.

VENTRICULAR VENTRICULAR SYSTEMSYSTEM

Ventricular system of the brain is actually a continuous Ventricular system of the brain is actually a continuous tube that is dilated in some parts to form ventricles.tube that is dilated in some parts to form ventricles.

It originates from the cavity of the neural tube.It originates from the cavity of the neural tube.

Components:Components:

● ● 2 lateral ventricles → inside cerebral hemispheres.2 lateral ventricles → inside cerebral hemispheres.

● ● third ventricle → inside diencephalon.third ventricle → inside diencephalon.

● ● aqueduct of Sylvius → inside brain stem.aqueduct of Sylvius → inside brain stem.

it connects the third to the fourth ventricles.it connects the third to the fourth ventricles.

● ● fourth ventricle → inside pons & medulla oblongata.fourth ventricle → inside pons & medulla oblongata.

Foramina:Foramina:

Some foramina connect ventricles to each other, these are:Some foramina connect ventricles to each other, these are:

2 foramina of Monro between lateral & third ventricle.2 foramina of Monro between lateral & third ventricle.

2 lateral foramina of Luschka & 1 median foramen of 2 lateral foramina of Luschka & 1 median foramen of Magendie.Magendie.

Choroid plexus:Choroid plexus:

a network of blood vessels that produce CSF.a network of blood vessels that produce CSF.

Lateral ventricles:Lateral ventricles:

▪ ▪ 2 cavities each lies inside a cerebral 2 cavities each lies inside a cerebral hemisphere separated from each other by hemisphere separated from each other by septum pellucidumseptum pellucidum

▪ ▪ A lateral ventricle is formed of A lateral ventricle is formed of --frontal hornfrontal horn in the frontal lobe. in the frontal lobe. --bodybody in the parietal lobe. in the parietal lobe. --posterior hornposterior horn in the occipital in the occipital lobelobe --temporal horntemporal horn in the temporal in the temporal lobe.lobe. … …..all meeting in a confluence ..all meeting in a confluence called called trigone (atrium) trigone (atrium) whichwhich contains the glomus that is a tuft contains the glomus that is a tuft of choroid plexus calcified & seenof choroid plexus calcified & seen in CT.in CT. ▪ ▪ Lateral ventricleLateral ventricle is related anteriorly tois related anteriorly to

the genu of corpus callosum, superiorly to the genu of corpus callosum, superiorly to the body of corpus callosum, inferiorly to the body of corpus callosum, inferiorly to the third ventricle in midline & infero-the third ventricle in midline & infero-laterally to the caudate nucleus & laterally to the caudate nucleus & thalami.thalami.

▪ ▪ Its posterior horn lies within the occipital Its posterior horn lies within the occipital lobe, while its temporal horn extends into lobe, while its temporal horn extends into the temporal horn with the hippocampus the temporal horn with the hippocampus lying on medial to it. lying on medial to it.

Third ventricle:Third ventricle: ▪ ▪ Single midline structure that lies inbetween Single midline structure that lies inbetween diencephalon structures ( thalamus & diencephalon structures ( thalamus & hypothalamus).hypothalamus). ▪ ▪ It has 4 recesses:It has 4 recesses: - preoptic & infundibular recesses - preoptic & infundibular recesses anteriorly.anteriorly. -suprapineal & pineal recesses-suprapineal & pineal recesses posteriorly.posteriorly. It is related superiorly to the fornix & inferiorly to: It is related superiorly to the fornix & inferiorly to: anterior commissure, optic chiasm, infundibulum of the pituitary gland, clivus, anterior commissure, optic chiasm, infundibulum of the pituitary gland, clivus,

midbrain & posterior commissure….while posteriorly it is related to the pineal body & midbrain & posterior commissure….while posteriorly it is related to the pineal body & splenium of corpus callosum.splenium of corpus callosum.

Fourth ventricle:Fourth ventricle: ▪ ▪ Roofed by the cerebellum posteriorly whileRoofed by the cerebellum posteriorly while pons & upper part of medulla oblongatapons & upper part of medulla oblongata form the floor (rhomboid fossa).form the floor (rhomboid fossa). ▪ ▪ It has 2 lateral recesses.It has 2 lateral recesses. ▪ ▪ It opens inferiorly into the central canal of It opens inferiorly into the central canal of the spinal cord.the spinal cord.

CAVUM VARIANTS:CAVUM VARIANTS:

Cavum septum pellucidum:Cavum septum pellucidum:• • Separates frontal horns of lateral ventricles Separates frontal horns of lateral ventricles

(anterior(anterior to to foramen of Monro)foramen of Monro)• • 80% of term infants; 15% of adults80% of term infants; 15% of adults• • May dilate; rare cause of obstructive May dilate; rare cause of obstructive

hydrocephalus.hydrocephalus.

Cavum vergae:Cavum vergae:• • Posterior continuation of cavum septum Posterior continuation of cavum septum

pellucidum; never exists without cavum pellucidum; never exists without cavum septum pellucidum.septum pellucidum.

• • 30% of term infants; 15% of adults.30% of term infants; 15% of adults.

Cavum velum interpositum:Cavum velum interpositum:• • Extension of quadrigeminal plate cistern to Extension of quadrigeminal plate cistern to

foramenforamen of of Monro Monro

CSF circulationCSF circulationFormation:Formation: --It is formed by choroid plexus that are It is formed by choroid plexus that are specialized cells covering blood vessels specialized cells covering blood vessels present in the lateral ventricle (bodypresent in the lateral ventricle (body temporal horn & trigone), third ventricletemporal horn & trigone), third ventricle & fourth ventricle.& fourth ventricle. --Blood supply to choroid plexus comes from Blood supply to choroid plexus comes from anterior choroidal artery (branch of theanterior choroidal artery (branch of the internal carotid artery) & posterior internal carotid artery) & posterior choroidal artery ( branch of the choroidal artery ( branch of the posterior cerebral artery).posterior cerebral artery).

Circulation: Circulation: -CSF formed in the lateral ventricle flows-CSF formed in the lateral ventricle flows to the third ventricle through the 2 to the third ventricle through the 2 foramina of Monro then down theforamina of Monro then down the aqueduct of Sylvius to the fourthaqueduct of Sylvius to the fourth ventricle, from which it passes to the ventricle, from which it passes to the subarachnoid space ( cisterna magna) subarachnoid space ( cisterna magna) via the median foramen of Magendie & via the median foramen of Magendie & the 2 lateral foramina of Luschka.the 2 lateral foramina of Luschka.

Absorption: Absorption: --Wide spread absorption occur through Wide spread absorption occur through

walls of dural venous sinuses, but sites walls of dural venous sinuses, but sites of greatest absorption are at the of greatest absorption are at the arachnoid villi especially in superior arachnoid villi especially in superior sagittal sinus.sagittal sinus.

CSF:CSF: 500 ml. are produced per day.500 ml. are produced per day.

140 ml. total volume.140 ml. total volume. 80-180 mm. water normal pressure from80-180 mm. water normal pressure from lumbar puncture for a patient in laterallumbar puncture for a patient in lateral decubitusdecubitus

Meninges & CSF spacesMeninges & CSF spaces Meninges are the membranes that cover the surface of the brain.Meninges are the membranes that cover the surface of the brain. They are 3 in number named: -dura mater.They are 3 in number named: -dura mater.

-arachnoid mater.-arachnoid mater.

-pia mater.-pia mater.

Dura mater:Dura mater:

☺ ☺ The outermost layer.The outermost layer.

☺ ☺ It covers the brain & spinal cord, however it doesn’t dip into sulci.It covers the brain & spinal cord, however it doesn’t dip into sulci.

☺ ☺ It ends caudally at the level of It ends caudally at the level of the second sacral vertebrathe second sacral vertebra as a thin fibrous band as a thin fibrous band

(filum terminale) that continues down to fuse with the coccyx.(filum terminale) that continues down to fuse with the coccyx.

☺ ☺ Dura mater is a tough fibrous layer formed by fusion of:Dura mater is a tough fibrous layer formed by fusion of:

1- an inner dura mater proper.1- an inner dura mater proper.

2- the periostium of skull bones that is attached to suture lines.2- the periostium of skull bones that is attached to suture lines.

… ….these 2 layers are tightly fused together except when they split to enclose .these 2 layers are tightly fused together except when they split to enclose

dural sinuses.dural sinuses.

☺ ☺ Superficial to dura mater is a potential space called extra-dural space, this space isSuperficial to dura mater is a potential space called extra-dural space, this space is

limited at suture lines.limited at suture lines.

☺ ☺ Deep to the dura another potential space; the sub-dural space, it lies between dura & Deep to the dura another potential space; the sub-dural space, it lies between dura &

arachnoid mater.arachnoid mater.

Dural folds:Dural folds: ♣ ♣ Falx cerebri:Falx cerebri: - It is formed when the 2 dural layers split to enclose the superior sagittal sinus, occupying the- It is formed when the 2 dural layers split to enclose the superior sagittal sinus, occupying the

interhemispheric fissure, extending from crista galli anteriorly till attachment to the interhemispheric fissure, extending from crista galli anteriorly till attachment to the

superior surface of tentorium cerebelli (another dural fold) posteriorly.superior surface of tentorium cerebelli (another dural fold) posteriorly.

- Its upper edge is attached to the skull, containing the superior sagittal sinus, while its lower edge is- Its upper edge is attached to the skull, containing the superior sagittal sinus, while its lower edge is

the free edge and it encloses the inferior sagittal sinus…..the straight sinus runs along the line of the free edge and it encloses the inferior sagittal sinus…..the straight sinus runs along the line of

attachment of falx cerebri to tentorium cerebelli.attachment of falx cerebri to tentorium cerebelli.

- The point where the 2 dural folds meet against the internal occipital protuberance is the site of - The point where the 2 dural folds meet against the internal occipital protuberance is the site of

confluence of dural venous sinuses.confluence of dural venous sinuses.

♣ ♣ Tentorium cerebelli:Tentorium cerebelli: - A horizontally placed dural fold that - A horizontally placed dural fold that

separates cerebral hemispheres superiorly separates cerebral hemispheres superiorly from cerebellum inferiorly.from cerebellum inferiorly.

- Its postero-lateral edge is attached to the - Its postero-lateral edge is attached to the skull bones at the boundaries of the skull bones at the boundaries of the posterior cranial fossa & anteriorly to the posterior cranial fossa & anteriorly to the posterior clinoid processes, enclosing the posterior clinoid processes, enclosing the transverse sinuses & forms the lateral transverse sinuses & forms the lateral wall of the cavernous sinus.wall of the cavernous sinus.

- Its anterior edge is a free edge that - Its anterior edge is a free edge that encircles the brain stem (at the tentorial encircles the brain stem (at the tentorial notch) and extends anteriorly to attach to notch) and extends anteriorly to attach to the anterior clinoid processes & forms the the anterior clinoid processes & forms the roof of the cavernous sinus.roof of the cavernous sinus.

♣ ♣ Diaphragma sellae:Diaphragma sellae: - A dural fold that is stretched between the- A dural fold that is stretched between the anterior & posterior clinoid processes.anterior & posterior clinoid processes. - It roofs the sella turcica & is pierced by the - It roofs the sella turcica & is pierced by the infundibulum of pituitary gland.infundibulum of pituitary gland.

♣ ♣ Falx cerebelli:Falx cerebelli: - A small dural fold attached to the internal- A small dural fold attached to the internal occipital crest & projects between the 2occipital crest & projects between the 2 cerebellar hemispheres.cerebellar hemispheres.

Arachnoid mater:Arachnoid mater:

-- -- A delicate connective tissue that lies between dura & pia mater.A delicate connective tissue that lies between dura & pia mater. the space between arachnoid & pia mater is the subarachnoid space through which thin trabeculae the space between arachnoid & pia mater is the subarachnoid space through which thin trabeculae

extend the 2 meningeal layers & it is the space within which CSF flows around brain.extend the 2 meningeal layers & it is the space within which CSF flows around brain. - At some parts this space widens to form the subarachnoid spaces:- At some parts this space widens to form the subarachnoid spaces: 1- cisterna magna.1- cisterna magna. 2- cisterna pontis (basilar artery).2- cisterna pontis (basilar artery). 3- cisterna interpeduncularis (trochlear nerve).3- cisterna interpeduncularis (trochlear nerve). 4- supra-sellar cistern (optic chiasm).4- supra-sellar cistern (optic chiasm). 5- pericallosal cistern.5- pericallosal cistern. 6- quadrigeminal cistern.6- quadrigeminal cistern. 7- ambient cistern.7- ambient cistern. 8- cistern of lateral fissure.8- cistern of lateral fissure.

Pia mater:Pia mater:

- A vascular layer intimately - A vascular layer intimately related to brain surface and related to brain surface and even invests into the sulci.even invests into the sulci. - Carries blood vessels to brain.- Carries blood vessels to brain.

Pituitary glandPituitary gland A small endocrinal gland that projects down from the inferior surface of the A small endocrinal gland that projects down from the inferior surface of the

brain to lie in sella turcica.brain to lie in sella turcica. It connected to the brain by the infundibulum.It connected to the brain by the infundibulum. It lies above the body of sphenoid bone (with sphenoid air sinus), below It lies above the body of sphenoid bone (with sphenoid air sinus), below

diaphragma sellae & inbetween the 2 cavernous sinuses.diaphragma sellae & inbetween the 2 cavernous sinuses. Optic chiasm is closely related to the gland lying antero-superior to it.Optic chiasm is closely related to the gland lying antero-superior to it.

Blood vesselsBlood vessels Arteries:Arteries:

1- Carotid system.1- Carotid system.

2- Vertebro-basilar system.2- Vertebro-basilar system.

Veins:Veins: 1- Cerebral veins.1- Cerebral veins.

2- Dural venous sinuses.2- Dural venous sinuses.

ArteriesArteriesCarotid system:Carotid system:-Formed of the internal carotid artery, it rises from the common carotid artery in the neck at the level of C6.-Formed of the internal carotid artery, it rises from the common carotid artery in the neck at the level of C6.-It runs upward till skull base to pass through the carotid canal (of petrous bone).-It runs upward till skull base to pass through the carotid canal (of petrous bone).-Then it curves forward & medially to emerge from foramen lacerum.-Then it curves forward & medially to emerge from foramen lacerum.-Emerging out from this foramen it goes into the cavernous sinus running forward then upward again beside body -Emerging out from this foramen it goes into the cavernous sinus running forward then upward again beside body

of sphenoid bone.of sphenoid bone.-It pierces the dura just lateral to the anterior clinoid process to run backward (carotid siphon) above the cavernous -It pierces the dura just lateral to the anterior clinoid process to run backward (carotid siphon) above the cavernous

sinus & below the optic nerve, then upward to divide into anterior & middle cerebral arteries below the sinus & below the optic nerve, then upward to divide into anterior & middle cerebral arteries below the anterior perforated substance.anterior perforated substance.

-Parts of the internal carotid artery:-Parts of the internal carotid artery: 1- Cervical part.1- Cervical part. 2- Petrous part.2- Petrous part. 3- Cavernous part.3- Cavernous part. 4- Cerebral (supra-clinoid) part.4- Cerebral (supra-clinoid) part.

Branches :Branches : Cervical part no branchesCervical part no branches

Petrous par - carotico-tympanic.Petrous par - carotico-tympanic.

- pterygoid.- pterygoid.

Cavernous part - cavernousCavernous part - cavernous

- hypophyseal.- hypophyseal.

- meningeal.- meningeal.

Cerebral part - ophthalmic.Cerebral part - ophthalmic.

- anterior cerebral. - anterior cerebral.

- middle cerebral. - middle cerebral.

- posterior communicating.- posterior communicating.

- anterior choroidal.- anterior choroidal.

Ophthalmic artery gives: central artery of retina.Ophthalmic artery gives: central artery of retina.

lacrimal artery.lacrimal artery.

muscular branches.muscular branches.

ciliary arteries.ciliary arteries.

supra-orbital artery.supra-orbital artery.

supra-trochlear artery.supra-trochlear artery.

anterior ethmoidal artery.anterior ethmoidal artery.

posterior ethmoidal artery.posterior ethmoidal artery.

meningeal branch.meningeal branch.

medial palpebral arteries.medial palpebral arteries.

dorsal nasal artery. dorsal nasal artery.

Anterior cerebral artery:Anterior cerebral artery:

1- Central branches: 1- Central branches:

These penetrate through the posterior penetrated substance to supply anterior parts ofThese penetrate through the posterior penetrated substance to supply anterior parts of

corpus callosum & basal ganglia.corpus callosum & basal ganglia.

2- Cortical branches.2- Cortical branches.

3- Anterior communicating artery.3- Anterior communicating artery.

Middle cerebral artery:Middle cerebral artery: 1- central branches:1- central branches:

they pass through the anterior perforated substance to supply basal ganglia, they are: they pass through the anterior perforated substance to supply basal ganglia, they are: the lateral striate arteries, medial striate arteries & thalamo-striate artery (artery of cerebral the lateral striate arteries, medial striate arteries & thalamo-striate artery (artery of cerebral haemorrhage).haemorrhage).

2- cortical branches.2- cortical branches.

Segments of the anterior cerebral artery:Segments of the anterior cerebral artery:

A1 segment:A1 segment: runs beneath the frontal lobe. runs beneath the frontal lobe.

A2 segment:A2 segment: runs upward around the genu of corpus callosum. runs upward around the genu of corpus callosum.

A3 segment:A3 segment: actually it is the 2 terminal branches of the anterior cerebral artery; actually it is the 2 terminal branches of the anterior cerebral artery;

callosomarginal & pericallosal arteries.callosomarginal & pericallosal arteries.

Segments of the middle cerebral artery:Segments of the middle cerebral artery:

M1 segment ( the horizontal segment):M1 segment ( the horizontal segment): runs in the Sylvian fissure. runs in the Sylvian fissure.

M2 segment ( the insular segment):M2 segment ( the insular segment): this is formed of 2 or 3 branches of M1, they this is formed of 2 or 3 branches of M1, they

run on the insula, they give multiple branchesrun on the insula, they give multiple branches

(M3).(M3).

M3 segment ( the opercular segment):M3 segment ( the opercular segment): run over the frontoparietal & temporal run over the frontoparietal & temporal

opercula. opercula.

M4 segment (cortical branches):M4 segment (cortical branches): variable & complex, include temporal, ascending variable & complex, include temporal, ascending

frontoparietal, parietal, angular & posterior frontoparietal, parietal, angular & posterior

temporal branches.temporal branches.

Vertebro-basilar system:Vertebro-basilar system:

- Formed by 2 vertebral arteries (Rt & Lt) that Formed by 2 vertebral arteries (Rt & Lt) that arise fromarise from the subclavian arteries (1the subclavian arteries (1stst part) at part) at the root of the neck.the root of the neck.

- Each vertebral artery passes through foramina Each vertebral artery passes through foramina of the transverse processes of the upper of the transverse processes of the upper cervical vertebrae cervical vertebrae till cervical vertebrae cervical vertebrae till foramen magnum through which it enters foramen magnum through which it enters cranial cavity.cranial cavity.

- It runs up on the ventral surface of brain stem It runs up on the ventral surface of brain stem to join its fellow at lower border of pons to form to join its fellow at lower border of pons to form the basilar artery.the basilar artery.

- The basilar artery runs up till upper border of The basilar artery runs up till upper border of pons where it divides into Rt. & Lt. posterior pons where it divides into Rt. & Lt. posterior cerebral arteries.cerebral arteries.

- Branches:Branches:

Vertebral arteryVertebral artery:- spinal branches.:- spinal branches.

- muscular branches.- muscular branches.

- meningeal branches.- meningeal branches.

- posterior spinal artery.- posterior spinal artery.

- anterior spinal artery.- anterior spinal artery.

- posterior inferior cerebellar artery.- posterior inferior cerebellar artery.

- medullary arteries.- medullary arteries.

Basilar artery:Basilar artery:- pontine branches.- pontine branches.

- labyrinthine artery.- labyrinthine artery.

- anterior inferior cerebellar artery.- anterior inferior cerebellar artery.

- superior cerebellar artery.- superior cerebellar artery.

Posterior cerebral artery:Posterior cerebral artery:

- central branches. - posterior choroidal arteries.- central branches. - posterior choroidal arteries.

- cortical branches.- cortical branches.

Parts of posterior cerebral artery:Parts of posterior cerebral artery:

P1:P1: the segment before posterior communicating artery. the segment before posterior communicating artery.

P2 (ambient segment):P2 (ambient segment): runs in the ambient cistern. runs in the ambient cistern.

P3 (quadrigeminal segment):P3 (quadrigeminal segment): runs in quadrigeminal cistern. runs in quadrigeminal cistern.

P4:P4: the terminal portion of posterior cerebral artery that includes the occipital & the terminal portion of posterior cerebral artery that includes the occipital &

inferior temporal branches.inferior temporal branches.

Circle of Circle of Willis:Willis:

- This is an anastomotic circle formed by branches - This is an anastomotic circle formed by branches of carotid & vertebro-basilar system.of carotid & vertebro-basilar system.

- It provides alternative sources of blood when - It provides alternative sources of blood when there is deficiency in one of the arteries there is deficiency in one of the arteries supplying the brain, however it can only serve supplying the brain, however it can only serve this function with the gradually progressing this function with the gradually progressing deficiency not the sudden one.deficiency not the sudden one.

Circle of Willis is present in Circle of Willis is present in the interpeduncular cistern, the interpeduncular cistern, surrounding optic chiasm & surrounding optic chiasm & infundibulum of pituitary infundibulum of pituitary gland.gland.

Cerebral veins :Cerebral veins : 1- Superficial veins:1- Superficial veins: These are multiple veins that originate from subcortical medullary substance to run on the These are multiple veins that originate from subcortical medullary substance to run on the

surface of the brain, then pass through subarachnoid space to penetrate arachnoid mater & surface of the brain, then pass through subarachnoid space to penetrate arachnoid mater & drain into dural venous sinuses.drain into dural venous sinuses.

2- Deep veins:2- Deep veins: These drain deep parts of the brain; septal area, thalamus, basal ganglia, …These drain deep parts of the brain; septal area, thalamus, basal ganglia, … Include: - Saptal vein.Include: - Saptal vein. - Thalamostriate vein.- Thalamostriate vein. - Terminal vein.- Terminal vein. - Great vein of Galen (drains into the straight sinus).- Great vein of Galen (drains into the straight sinus).

Dural venous sinuses:Dural venous sinuses: - Endothelium lined spaces created by splitting of dura mater at certain areas on inner surface - Endothelium lined spaces created by splitting of dura mater at certain areas on inner surface

of the skull.of the skull.

- All cerebral veins drain into them & they drain into the internal jugular veins.- All cerebral veins drain into them & they drain into the internal jugular veins.

- They include:- They include:

1- Superior sagittal sinus. 2- Inferior sagittal sinus. 1- Superior sagittal sinus. 2- Inferior sagittal sinus.

3- Straight sinus. 4- Rt. & Lt. transverse sinuses.3- Straight sinus. 4- Rt. & Lt. transverse sinuses.

5- Sigmoid sinus. 6- Superior petrosal sinus.5- Sigmoid sinus. 6- Superior petrosal sinus.

7- Inferior petrosal sinus. 8- Cavernous sinus.7- Inferior petrosal sinus. 8- Cavernous sinus.

Cross sectional Cross sectional anatomyanatomy

Imaging of the Imaging of the brainbrain

Imaging modalities Imaging modalities include:include:

1- CT.1- CT. 2- MRI.2- MRI. 3- Angiography.3- Angiography. 4- Radio-isotope scanning4- Radio-isotope scanning (PET & SPECT).(PET & SPECT). 5- Ultrasound & Doppler.5- Ultrasound & Doppler. 6- Others: - plain X-ray.6- Others: - plain X-ray. - cisternography.- cisternography. - pneumography.- pneumography. - thermography.- thermography. - air meatography.- air meatography.

CT scanCT scan

Godfrey Hounsfield a physist who, Godfrey Hounsfield a physist who, together with Dr. James Ambrose together with Dr. James Ambrose (a consultant radiologist) (a consultant radiologist) developed the first CT scanner in developed the first CT scanner in 1971 in England1971 in England

☺ ☺ The idea of Ct depends on receiving the x-rays coming out of the The idea of Ct depends on receiving the x-rays coming out of the patient by detectors (instead of a photosensitive film), these detectors patient by detectors (instead of a photosensitive film), these detectors transmit data to a computer that through a certain equation processes transmit data to a computer that through a certain equation processes these data & introduces them as a cross sectional image.these data & introduces them as a cross sectional image.

☺ ☺ CT scanners have developed into different generations from the first CT scanners have developed into different generations from the first to the fourth generation according to shape of x-ray beam, number of to the fourth generation according to shape of x-ray beam, number of detectors & the relative movement of both to each other.detectors & the relative movement of both to each other.

Indications of CT scanning of Indications of CT scanning of the brain:the brain:

these include suspected intra-these include suspected intra-cranial lesions either traumatic (as extra- cranial lesions either traumatic (as extra- or sub-dural haematoma, intra-cerebral or sub-dural haematoma, intra-cerebral contusions,….) or non traumatic (as contusions,….) or non traumatic (as cerebral infarctions, intra-cerebral cerebral infarctions, intra-cerebral haemorrhage, neoplasm, abscess,…..).haemorrhage, neoplasm, abscess,…..).

Protocol:Protocol: - scanning can be done in axial & coronal - scanning can be done in axial & coronal

planes according to site & nature of planes according to site & nature of pathology.pathology.

- sagittal & a 3 dimensional images can - sagittal & a 3 dimensional images can be obtained through reconstruction of be obtained through reconstruction of data.data.

- the patient lies supine on couch then a - the patient lies supine on couch then a lateral topogram is acquired (similar to a lateral topogram is acquired (similar to a plain x-ray skull lateral view) to have a plain x-ray skull lateral view) to have a map of the area to be examined & plan map of the area to be examined & plan the study.the study.

- the baseline plane is about 15 degrees - the baseline plane is about 15 degrees to the orbito-meatal line.to the orbito-meatal line.

slice thickness:slice thickness:

5 mm. for the posterior fossa & 10 5 mm. for the posterior fossa & 10 mm. for the rest of the brain.mm. for the rest of the brain.

10 mm. all through the brain for 10 mm. all through the brain for emergencies.emergencies.

Use of a contrast Use of a contrast medium:medium: - cases of intra-cerebral - cases of intra-cerebral haemorrhage, infarctions, haemorrhage, infarctions, hydrocephalus & trauma use hydrocephalus & trauma use of a contrast medium is not of a contrast medium is not usually required.usually required. - suspected cases of - suspected cases of neoplasm, infective diseases neoplasm, infective diseases & vascular lesions, a pre- & & vascular lesions, a pre- & post-contrast study are post-contrast study are required to increase required to increase diagnostic accuracy through diagnostic accuracy through the pattern of enhancement of the pattern of enhancement of these lesions.these lesions.

Contrast medium:Contrast medium: urographin 50-100 ml. urographin 50-100 ml. 300-370 mgI/ml. 300-370 mgI/ml. HandHand injectioninjection

Radiographic anatomyRadiographic anatomy

In some situations (as in the search of In some situations (as in the search of pituitary gland pathology) coronal CT pituitary gland pathology) coronal CT study is performed with thinner slice study is performed with thinner slice thickness (3 mm.), the baseline then is thickness (3 mm.), the baseline then is perpendicular to the hard palate with the perpendicular to the hard palate with the patient lying in prone position.patient lying in prone position.

For detection of bone pathology in For detection of bone pathology in association of brain pathology, bone association of brain pathology, bone widow can display an adequate image of widow can display an adequate image of bone & a high resolution can be done.bone & a high resolution can be done.

Other CT techniques:Other CT techniques:

1- Perfusion computed tomography:1- Perfusion computed tomography: - This is a CT study of regional blood flow to brain. - This is a CT study of regional blood flow to brain.

- It detects amount of blood flow to a specific area in cerebral blood vessel or brain - It detects amount of blood flow to a specific area in cerebral blood vessel or brain

parenchyma through detection of changes in Hounsfield units over time before & parenchyma through detection of changes in Hounsfield units over time before &

after injection of a contrast medium.after injection of a contrast medium.

2- Xenon computed tomography:2- Xenon computed tomography: - This study relies on the fact that Xenon attenuates X-rays similar to iodine & the fact- This study relies on the fact that Xenon attenuates X-rays similar to iodine & the fact

that it can pass through blood-brain barrier.that it can pass through blood-brain barrier.

- Xenon is inhaled & at the same time CT study is performed recording changes in - Xenon is inhaled & at the same time CT study is performed recording changes in

Hounsfield units over time & translating them into a coloured map in which each Hounsfield units over time & translating them into a coloured map in which each

colour denotes a value for blood flow.colour denotes a value for blood flow.

These 2 studies are specifically helpful in cerebrovascular diseases especially These 2 studies are specifically helpful in cerebrovascular diseases especially early detection of strokes.early detection of strokes.

3- CT angiography.3- CT angiography.

M R IM R I The principle of MRI (Magnetic The principle of MRI (Magnetic

Resonance Imaging) comes from the Resonance Imaging) comes from the assumption that if an odd numbered assumption that if an odd numbered nucleus is placed in a magnetic field it nucleus is placed in a magnetic field it behaves as a small bar magnet, so if it is behaves as a small bar magnet, so if it is hit with radio-wave pulses (sequence) hit with radio-wave pulses (sequence) with different time intervals (TR, TE/2 ) with different time intervals (TR, TE/2 ) this nucleus sends back a signal that is this nucleus sends back a signal that is different according to the tissue.different according to the tissue.

So, different signals of different So, different signals of different intensities build up a contrast between intensities build up a contrast between different tissues, as seen on an imagedifferent tissues, as seen on an image

AcAcccoorrdidinngg toto tthe he ttiimme e iinntteervarvall bbeettwweeeenn pulses, images acquired are called T1, pulses, images acquired are called T1, T2, proton density,….T2, proton density,….

Standard protocol:Standard protocol:- Different planes can be acquired (axial, sagittal &coronal) with the patient in supine position.- Different planes can be acquired (axial, sagittal &coronal) with the patient in supine position.

- Usually T2- weighted images are acquired first in coronal or axial planes, then T1-weighted - Usually T2- weighted images are acquired first in coronal or axial planes, then T1-weighted images are taken pre-& post-contrast.images are taken pre-& post-contrast.

- Axial images are parallel to the hard palate & the coronal images are perpendicular to it.- Axial images are parallel to the hard palate & the coronal images are perpendicular to it.

Indications:Indications:- Suspected parenchymal brain lesion as haemorrhage, tumours, multiple sclerosis,…- Suspected parenchymal brain lesion as haemorrhage, tumours, multiple sclerosis,…

- Suspected vascular brain lesion as aneurysm,…- Suspected vascular brain lesion as aneurysm,…

Contraindications:Contraindications:- Presence of metallic object as ferromagnetic aneurysmal clips, pacemakers, suspected metallic - Presence of metallic object as ferromagnetic aneurysmal clips, pacemakers, suspected metallic

foreign body,…..foreign body,…..

- These objects may move, dislodge, heat up or dysfunction.- These objects may move, dislodge, heat up or dysfunction.

Contrast medium:Contrast medium:- Gadolinium-DTPA - Gadolinium-DTPA

- 0.2 ml./kg. body weight- 0.2 ml./kg. body weight

- Hand injection- Hand injection

♥♥ ♥♥ Proton density image Proton density image

fast spin echo sequence fast spin echo sequence

TR/TE =3000/20.TR/TE =3000/20.

♥♥ ♥♥T2 weighted image T2 weighted image

fast spin echo sequence fast spin echo sequence

TR/TE =3000/90.TR/TE =3000/90.

♥♥ ♥♥ T1 weighted image T1 weighted image

spin echo sequence spin echo sequence

TR/TE =400/14.TR/TE =400/14.

RADIOLOGICAL RADIOLOGICAL ANATOMYANATOMY

Other MRI techniques:Other MRI techniques:

1- MR diffusion imaging:1- MR diffusion imaging: This technique depends on the constant random movement of water molecules across This technique depends on the constant random movement of water molecules across

membranes, this movement depends on energy delivered by blood supply.membranes, this movement depends on energy delivered by blood supply. So when blood supply to an area in the brain, movement slows or stops reflecting changes in So when blood supply to an area in the brain, movement slows or stops reflecting changes in

the diffusion-weighted MRI image that uses certain sequence that records this movement.the diffusion-weighted MRI image that uses certain sequence that records this movement.

2- MR spectroscopy:2- MR spectroscopy: Some substances in brain send characteristic signals on MRI.Some substances in brain send characteristic signals on MRI. These substances are affected (and hence their signals) by certain diseases.These substances are affected (and hence their signals) by certain diseases.

3-Functional MRI:3-Functional MRI: Detects changes in signal intensity at a specific region (region of interest) associated with Detects changes in signal intensity at a specific region (region of interest) associated with

activation of this region.activation of this region.

4- MR perfusion imaging.4- MR perfusion imaging.

5- MR angiography.5- MR angiography.

Which is better, CT OR MRI ?Which is better, CT OR MRI ?

MRI is much more superior than CT if we are looking for a parenchymal MRI is much more superior than CT if we are looking for a parenchymal lesion, MRI gives better definition & anatomy of the brain tissue. Also lesion, MRI gives better definition & anatomy of the brain tissue. Also it carries no hazards of ionizing radiation.it carries no hazards of ionizing radiation.

However, if a bone lesion is suspected or being looked for, MRI would However, if a bone lesion is suspected or being looked for, MRI would be useless & CT would be the method of choice.be useless & CT would be the method of choice.

Also MRI takes so much time & is not suitable in some situations as Also MRI takes so much time & is not suitable in some situations as claustrophobic patients, patients with pacemakers or ferro-magnetic claustrophobic patients, patients with pacemakers or ferro-magnetic objects.objects.

ANGIOGRAPHYANGIOGRAPHY Angiography is the opacification of blood vessels through Angiography is the opacification of blood vessels through

the intra-venous injection of a contrast material.the intra-venous injection of a contrast material.

It can be performed using:It can be performed using:

1- Conventional X-rays. 1- Conventional X-rays.

2- CT angiography.2- CT angiography.

3- MR angiography.3- MR angiography.

Conventional angiographyConventional angiography Indications:Indications: 1- Investigations of cerebral aneurysms in cases of subarachnoid1- Investigations of cerebral aneurysms in cases of subarachnoid

haemorrhage.haemorrhage.

2- Investigation of AVM.2- Investigation of AVM.

3- Highly vascular tumours as a pre-operative assessment.3- Highly vascular tumours as a pre-operative assessment.

Types:Types: 1- Carotid angiography.1- Carotid angiography.

2- Vertebral angiography.2- Vertebral angiography.

3- Dural sinuses venography.3- Dural sinuses venography.

Carotid angiography:Carotid angiography:

It studies the anterior circulation ( internal carotid artery)It studies the anterior circulation ( internal carotid artery)

Technique:Technique:1- Direct puncture of the carotid artery at the level of cricoid cartilage.1- Direct puncture of the carotid artery at the level of cricoid cartilage.2- Indirect; through femoral artery.2- Indirect; through femoral artery.

AArtery is punctured with a special needle, a guide wire is inserted then a catheter is placed along the guide wire.rtery is punctured with a special needle, a guide wire is inserted then a catheter is placed along the guide wire.Catheter is pushed up to the aortic arch, swinged to lie against the opening of the common carotid ( or Catheter is pushed up to the aortic arch, swinged to lie against the opening of the common carotid ( or

brachiocephalic artery) & pushed up the common carotid then the internal carotid artery.brachiocephalic artery) & pushed up the common carotid then the internal carotid artery.TTest injections are done frequently to guide the way up the arterial tree.est injections are done frequently to guide the way up the arterial tree.Contrast medium is injected (6ml. hand injection).Contrast medium is injected (6ml. hand injection).

Images:Images: Views: 1- Town’s view.Views: 1- Town’s view. 2- Lateral view.2- Lateral view. 3- anterior oblique view.3- anterior oblique view. Image acquisition:Image acquisition: 2 images at 2 sec. run time.2 images at 2 sec. run time. 1 image at 6 sec. run time.1 image at 6 sec. run time. for each view.for each view.

Radiological anatomy:Radiological anatomy:

Vertebral angiography:Vertebral angiography:

It studies the posterior circulation (the vertebro-basilar system).It studies the posterior circulation (the vertebro-basilar system).

Technique:Technique:

The same as carotid angiography, but catheter is passed through the The same as carotid angiography, but catheter is passed through the subclavian artery into the vertebral artery.subclavian artery into the vertebral artery.

Images are taken in Town’s view.Images are taken in Town’s view.

Lateral view.Lateral view.

Dural sinus Dural sinus venography:venography:

It demonstrates the patency of dural sinuses.It demonstrates the patency of dural sinuses.

It is not a separate examination, it is actually the venous It is not a separate examination, it is actually the venous phase of arteriography.phase of arteriography.

CT angiographyCT angiography

With the introduction of spiral CT ( and With the introduction of spiral CT ( and more so with the multislice CT) more so with the multislice CT) selective reconstruction of cerebral selective reconstruction of cerebral blood vessels became possible.blood vessels became possible.

Images are acquired at slice collimation of Images are acquired at slice collimation of 2 mm., table speed of 3 mm., 2 mm., table speed of 3 mm., reconstruction interval of 1 sec. & reconstruction interval of 1 sec. & gantry rotation of .75 sec. injecting gantry rotation of .75 sec. injecting 120 ml of contrast at a rate of 120 ml of contrast at a rate of 3ml/sec.3ml/sec.

Blood vessels can be displayed either as Blood vessels can be displayed either as 2D or 3D images.2D or 3D images.

MR angiographyMR angiography

The basic idea behind it is simply that if we magnetize a specific slice The basic idea behind it is simply that if we magnetize a specific slice including blood vessels within this slice & the blood cells inside the vessel, including blood vessels within this slice & the blood cells inside the vessel, by time we record signals from this slice magnetized blood cells would have by time we record signals from this slice magnetized blood cells would have been moved along the vessel so we receive signals from the been moved along the vessel so we receive signals from the new cells new cells

TIME-OF-FLIGHT MRATIME-OF-FLIGHT MRA

Another way of MRA acquisition is to receive signals from a slice Another way of MRA acquisition is to receive signals from a slice then neutralize movement of blood in vessels.then neutralize movement of blood in vessels.

PHASE CONTRAST MRAPHASE CONTRAST MRA

Also gadolinium can be injected to have Also gadolinium can be injected to have CONTRAST ENHANCED MRACONTRAST ENHANCED MRA

These changes in signals are These changes in signals are recorded, processed, reconstructed recorded, processed, reconstructed & displayed as 2D or 3D images.& displayed as 2D or 3D images.

SO……WHICH IS BETTER; COVENTIONAL, SO……WHICH IS BETTER; COVENTIONAL, CTCT OR OR MRIMRI ANGIOGRAPHY ????? ANGIOGRAPHY ?????

Conventional angiography is the basic study of blood vessels offering an Conventional angiography is the basic study of blood vessels offering an excellent visualization of blood vessels & their pathology, however it is excellent visualization of blood vessels & their pathology, however it is an invasive examination with more hazards relative to CT &MR an invasive examination with more hazards relative to CT &MR angiography.angiography.

MRA is a non-invasive examination & offers good visualization of MRA is a non-invasive examination & offers good visualization of vessels, but it is time consuming, unsuitable for claustrophobic patients vessels, but it is time consuming, unsuitable for claustrophobic patients & turbulence in blood flow may affect signals.& turbulence in blood flow may affect signals.

CT angiography is easier than conventional & MRA, needs less time, CT angiography is easier than conventional & MRA, needs less time, suitable for claustrophobic patients & can produce 2D & 3D images (like suitable for claustrophobic patients & can produce 2D & 3D images (like MRA), however it doesn’t give the best resolution especially with the MRA), however it doesn’t give the best resolution especially with the artifacts of calcium plaques which may be present at stenotic parts of artifacts of calcium plaques which may be present at stenotic parts of vessels.vessels.

ULTRASOUNDULTRASOUND

☼ ☼ Ultrasound waves are mechanical waves below the range audible by man.Ultrasound waves are mechanical waves below the range audible by man.

☼ ☼ These waves are generated by a piezo-electric material, reflect upon media These waves are generated by a piezo-electric material, reflect upon media interfaces & received by the piezo-electric material.interfaces & received by the piezo-electric material.

☼ ☼ Normally ultrasound waves are reflected by bone, so this modality cannot be Normally ultrasound waves are reflected by bone, so this modality cannot be used for normal adult skull, however it is used for infants through patent used for normal adult skull, however it is used for infants through patent fontanelles.fontanelles.

☼ ☼ Indications include: Congenital anomalies, hydrocephalus, intracranial Indications include: Congenital anomalies, hydrocephalus, intracranial haemorrhage & intracranial cysts.haemorrhage & intracranial cysts.

☻ ☻ Images are acquired in Images are acquired in sagittal & coronal planes sagittal & coronal planes through the anterior fontanelle through the anterior fontanelle & in axial plane through the & in axial plane through the antero-lateral fontanelle.antero-lateral fontanelle.

☻ ☻ A 5-7.5 MHz transducer is A 5-7.5 MHz transducer is used.used.

☻ ☻ US offers a non-invasive, US offers a non-invasive, cheap & portable method of cheap & portable method of brain imagingbrain imaging

DOPPLERDOPPLER

Using the same principle of ultrasound, doppler detects & displays blood Using the same principle of ultrasound, doppler detects & displays blood flow through the carotid vessels.flow through the carotid vessels.

Recording waves from the common, external & internal carotid arteries is Recording waves from the common, external & internal carotid arteries is performed with detection of stenosis & plaques.performed with detection of stenosis & plaques.

This is especially important for cases of stoke & TIA.This is especially important for cases of stoke & TIA. CUS is a 2-step, or "duplex," procedure. CUS is a 2-step, or "duplex," procedure.

The 2 steps are as The 2 steps are as follows:follows:

1-Imaging:1-Imaging:

-Imaging is accomplished with the brightness -Imaging is accomplished with the brightness mode (B-mode) technique. mode (B-mode) technique.

-The image usually is done in gray-scale, which -The image usually is done in gray-scale, which is a brightness scale. is a brightness scale.

-Sometimes, color flow information is -Sometimes, color flow information is superimposed on the gray-scale image. By superimposed on the gray-scale image. By convention, the color of the pulsating artery is convention, the color of the pulsating artery is red. This is called color Doppler imaging. red. This is called color Doppler imaging.

2-Spectral analysis:2-Spectral analysis:

-This allows measurement of blood flow -This allows measurement of blood flow velocity. velocity.

-A probing cursor is placed in the artery (on the -A probing cursor is placed in the artery (on the screen) and a signal intended to represent screen) and a signal intended to represent

blood flow velocity is generated. blood flow velocity is generated. -The signal is both visual and auditory. -The signal is both visual and auditory. -The signal has peaks and ebbs, which -The signal has peaks and ebbs, which

correspond to systolic and diastolic blood flow. correspond to systolic and diastolic blood flow. The peaks and ebbs create the "spectrum." The peaks and ebbs create the "spectrum."

Vessel identification:Vessel identification:

Identify common carotid artery: -Pulsatile walls -Smaller caliber than jugular vein -Systolic peak and diastolic endpoints in between that of external and internal carotid arteries on spectral analysis.

Distinguishing internal and external carotid arteries:

-ECA has smaller caliber. -ICA is often posterolateral to ECA. -ECA may have superior thyroid artery branch coming off. -ECA has virtually no diastolic flow

on spectral analysis (i.e., high resistance vessel). -ECA shows positive "temporal tap" (i.e., undulations in waveform with tapping of temporal artery).

Identifying vertebral artery: -With probe parallel to carotid, angle probe laterally and inferiorly. -Look for vertebral body processes that appear as hypoechoic transverse bars. -Vertebral artery runs perpendicular to vertebral processes.

SSINGLE INGLE PPHOTON HOTON EEMISSION MISSION CCOMPUTED OMPUTED TTOMOGRAPHYOMOGRAPHY

(SPECT)(SPECT)

This is a form of radio-isotope scanning where a radio-This is a form of radio-isotope scanning where a radio-pharmaceutical is injected to flow with the cerebral blood flow, pharmaceutical is injected to flow with the cerebral blood flow, emitting gamma rays that are detected with a gamma camera emitting gamma rays that are detected with a gamma camera & passed to a computer to process information & display it as & passed to a computer to process information & display it as a coloured map.a coloured map.

This technique can be used to study:This technique can be used to study:

-Cerebral blood flow.-Cerebral blood flow.

-Uptake by tumours.-Uptake by tumours.

Examples of radiopharmaceuticals Examples of radiopharmaceuticals include:include:

133133Xe, Xe, 123123I isopropyle iodo-amphetamine I isopropyle iodo-amphetamine (IMP) & (IMP) & 99m99mTc ethyl cycteinate Tc ethyl cycteinate

PPOSITRON OSITRON

EEMISSION MISSION

TTOMOGRAPHYOMOGRAPHY (PET)(PET)

This is imaging through the injection of radiopharmaceuticals This is imaging through the injection of radiopharmaceuticals that emit …….that emit …….

positronspositrons

WHAT ARE POSITRONSWHAT ARE POSITRONS

Positrons are positively charged Positrons are positively charged electrons, these combine with an electrons, these combine with an adjacent electron in adjacent electron in anninhilation reaction leading to anninhilation reaction leading to the emission of 2 high energy the emission of 2 high energy gamma rays in opposite gamma rays in opposite directions that are detected, their directions that are detected, their position is calculated & a amp of position is calculated & a amp of the radiopharmaceutical the radiopharmaceutical distribution is put into a map.distribution is put into a map.

PET imaging was based initially on the PET imaging was based initially on the use labeled O2. This preference for the use labeled O2. This preference for the O2 was mainly due to the fact that the O2 was mainly due to the fact that the main applications were related to the main applications were related to the brain regional oxygen metabolism and brain regional oxygen metabolism and blood volume. Mid 70's the blood volume. Mid 70's the cyclotroncyclotron enters the clinical world by making enters the clinical world by making available new isotopes such as 11C, available new isotopes such as 11C, 13N, 18F.13N, 18F.

PET acceptance was boosted by the PET acceptance was boosted by the development of 18F labeled 2-development of 18F labeled 2-fluorodeoxy-D-glucose (shortly called fluorodeoxy-D-glucose (shortly called FDGFDG ) with an optimal half-life of ) with an optimal half-life of almost 2 hours and its ideal property almost 2 hours and its ideal property of giving precise values of energy of giving precise values of energy metabolism not only for the brain or metabolism not only for the brain or heart but also for other organs. heart but also for other organs.

The glucose is an important energetic The glucose is an important energetic substrate with a simple chemical substrate with a simple chemical formula which is amply metabolized by formula which is amply metabolized by the the neoplasticneoplastic cells. cells.

Examples of Examples of PET images:PET images:

☻☻EpilepsyEpilepsy

Pinpointing epileptic fociPinpointing epileptic foci Most of the patients with epilepsy suffer from Most of the patients with epilepsy suffer from focal (partial) epilepsy that cannot be controlled focal (partial) epilepsy that cannot be controlled with medication. These patients may be good with medication. These patients may be good candidates for resection of the affected area of candidates for resection of the affected area of the brain; however, it is very difficult to the brain; however, it is very difficult to accurately identify the epilepsy focus. Inserting accurately identify the epilepsy focus. Inserting depth electrode implants is one method of depth electrode implants is one method of locating the foci, but it is expensive, highly locating the foci, but it is expensive, highly invasive, and associated with high rates of invasive, and associated with high rates of mortality, morbidity and infection. mortality, morbidity and infection. PET is a non-invasive and cost-effective aid in PET is a non-invasive and cost-effective aid in predicting the prognosis and in surgical predicting the prognosis and in surgical planning for resection procedures. By revealing planning for resection procedures. By revealing areas of increased and decreased glucose areas of increased and decreased glucose utilization, PET helps surgeons pinpoint the utilization, PET helps surgeons pinpoint the surgical site.surgical site.

Focal area of diminished FDG uptake in Rt. Frontal cortexFocal area of diminished FDG uptake in Rt. Frontal cortex

☺☺AlzheimerAlzheimerPET is being used to diagnose a wide PET is being used to diagnose a wide

variety of dementias by showing a variety of dementias by showing a distinct pattern of decreased glucose distinct pattern of decreased glucose consumption in the temporal/ parietal consumption in the temporal/ parietal regions of the brain, PET provides regions of the brain, PET provides early detection of the disease and early detection of the disease and helps eliminating both the uncertainty helps eliminating both the uncertainty associated with indefinite diagnosis associated with indefinite diagnosis and the need for multiple expensive and the need for multiple expensive tests. tests.

Marked reduction of FDG uptake in Rt. frontal, parietal & temporal regionsMarked reduction of FDG uptake in Rt. frontal, parietal & temporal regions

Other modalitiesOther modalities

Plain X-ray:Plain X-ray: ◘ ◘ Plain X-ray skull is usually a routine Plain X-ray skull is usually a routine

investigation to be done in any investigation to be done in any suspected pathology to the head, suspected pathology to the head, however it doesn’t give direct however it doesn’t give direct information as regards brain information as regards brain pathology.pathology.

◘ ◘ It can just demonstrate the effect of It can just demonstrate the effect of brain pathology on skull bones as brain pathology on skull bones as widened sella turcica in pituitary widened sella turcica in pituitary adenomas.adenomas.

◘ ◘ It is replaced by the more informative It is replaced by the more informative CT.CT.

Cisternography:Cisternography: It is the delineation of cisterns using contrast medium.It is the delineation of cisterns using contrast medium.

It can be done with -conventional X-ray.It can be done with -conventional X-ray.

-CT.-CT.

CT cisternography is done only to detect CSF leak:CT cisternography is done only to detect CSF leak:

.a lumber puncture is done to inject the contrast into lumber cistern, then the patient .a lumber puncture is done to inject the contrast into lumber cistern, then the patient lies prone on the couch & coronal cuts are taken.lies prone on the couch & coronal cuts are taken.

.bilateral jugular pressure may help to show site of leak..bilateral jugular pressure may help to show site of leak.

Ventriculography:Ventriculography:

This is delineation of ventricles.This is delineation of ventricles.

It can be done using contrast medium or air.It can be done using contrast medium or air.

Air Air meatography:meatography:

Done to detect suspected tumours of the 8Done to detect suspected tumours of the 8 thth cranial nerve. cranial nerve.

The patient lies in lateral decubitus with the affected side The patient lies in lateral decubitus with the affected side up, 2-3 ml. of air is injected into the subarachnoid up, 2-3 ml. of air is injected into the subarachnoid space through lumber puncture.space through lumber puncture.

Thin axial cuts are taken in region of internal auditory Thin axial cuts are taken in region of internal auditory meatus, if tumour is present air will not pass to the meatus, if tumour is present air will not pass to the meatusmeatus

Thermography:Thermography: It is the detection of cerebral blood flow through It is the detection of cerebral blood flow through

measurement of transmitted heat to foreheadmeasurement of transmitted heat to forehead..

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