Lecture Objectives..Lecture Objectives..

Students at the end of the lecture will be able to:

• Identify the different radiological modalities used for evaluation of CNS

• Identify the indication and contraindication for each modality

• Identify the radiological anatomy of brain and its vasculatures in different modalities.

The Radiological Investigation Used For The Radiological Investigation Used For Evaluation of The Brain and SkullEvaluation of The Brain and Skull

• 1.Plain x-ray Skull1.Plain x-ray Skull• 2.CT Scan2.CT Scan• 3.MRI3.MRI• 4.MRA , MRV & CTA4.MRA , MRV & CTA• 5.Catheter angiogram5.Catheter angiogram• 6.Duplex U/S of carotid arteries6.Duplex U/S of carotid arteries• 7.Ultrasound for neonatal brain7.Ultrasound for neonatal brain

The Radiological Investigation Used For The Radiological Investigation Used For Evaluation of The Brain and SkullEvaluation of The Brain and Skull

The newer imaging modalities have had a The newer imaging modalities have had a great impact on the diagnosis of diseases of great impact on the diagnosis of diseases of the central nervous system.the central nervous system.

CT and MRI have become the standard CT and MRI have become the standard investigations for disorders of the brain.investigations for disorders of the brain.

Plain films are still the initial investigation for Plain films are still the initial investigation for disorders of the bones of the skull – disorders of the bones of the skull – particularly fractures, but otherwise have particularly fractures, but otherwise have limited uses.limited uses.

Plain x-ray skull

Indications: Indications:

• traumatrauma• congenitalcongenital• calcification: normal or abnormal (vascular calcification: normal or abnormal (vascular

,neoplasm),neoplasm)• metastasis: lytic /scleroticmetastasis: lytic /sclerotic• multiple myelomamultiple myeloma• metabolic disordersmetabolic disorders• •

Plain x-ray skull

SELLA SELLA TURCICATURCICA

GROOVE GROOVE FOR MCAFOR MCA

EXT.AUD EXT.AUD MEATUSMEATUS ORBITAL ORBITAL

GROOVEGROOVE

Coronal Coronal suturesutureFrontal sinus

orbit

Ethmoid sinuses

Mastoid air cellsMastoid air cellsmandiblemandible

LL

Petrous bonePetrous bone

SKULL PA VIEW

Plain x-ray skull

TOWENS VIEW (AP)TOWENS VIEW (AP)

F.MAGNUMF.MAGNUMIAMsIAMs

LAMBDOID LAMBDOID SUTURESUTURE

Dorsum sellaeDorsum sellae

Ant. arch C1Ant. arch C1

Carotid canalCarotid canal

Occipital condyleOccipital condyle

OdontoidOdontoid

MandibleMandible

Foramen ovaleForamen ovale

Foramen Foramen spinosumspinosum

submentovertical VIEW submentovertical VIEW

CT SCAN ..CT SCAN ..

CT SCAN..CT SCAN..

• Using ionizing radiationUsing ionizing radiation

• Spiral CT can perform a head scan in 15 Spiral CT can perform a head scan in 15 minutes pre minutes pre

• &post contrast scans.&post contrast scans. • The scan itself can take as little as 10 The scan itself can take as little as 10

seconds.seconds.

• Patient preparation: nilPatient preparation: nil

• Type of the contrast medium: iodinated Type of the contrast medium: iodinated contrastcontrast

• (non ionic L.O.C.M)(non ionic L.O.C.M)

CT SCAN..CT SCAN..

Indications: Indications: • TraumaTrauma• detection of blooddetection of blood• strokesstrokes• tumourstumours• infection infection • Vascular disordersVascular disorders

Contraindications Contraindications DisadvantagesDisadvantages

CT SCAN..CT SCAN..

• The axial plane is the routine The axial plane is the routine projection but it is sometimes projection but it is sometimes possible to obtain direct coronal possible to obtain direct coronal scans.scans.

• The window settings are selected The window settings are selected for the brain, but may be altered for the brain, but may be altered to show the bones. to show the bones.

CT SCAN..CT SCAN..

• CSF is seen as water density (black) within CSF is seen as water density (black) within ventricular system and subarachnoid space.ventricular system and subarachnoid space.

• Grey matter is differentiated from white matter Grey matter is differentiated from white matter (white matter is relatively darker than grey (white matter is relatively darker than grey matter).matter).

• The falx is denser than the brain.The falx is denser than the brain.

• Large arteries and venous sinuses can be Large arteries and venous sinuses can be recognized when opacified by contrast medium.recognized when opacified by contrast medium.

• Posterior fossa may be obscured by artifacts Posterior fossa may be obscured by artifacts from overlying temporal and occipital bone.from overlying temporal and occipital bone.

NORMAL CT BRAIN

CT SCAN..CT SCAN..

A. OrbitB. Sphenoid SinusC. Temporal LobeD.Externa Auditory CanalE. Mastoid Air CellsF. Cerebellar Hemisphere

CT SCAN..CT SCAN..

A. Frontal LobeB. Frontal Bone (Superior Surface of Orbital Part)C. Dorsum SellaeD. Basilar ArteryE. Temporal LobeF. Mastoid Air CellsG. Cerebellar Hemisphere

CT SCAN..CT SCAN..

A. Anterior Horn of the Lateral VentricleB. Caudate NucleusC. Anterior Limb of the Internal CapsuleD. Putamen and Globus PallidusE. Posterior Limb of the Internal CapsuleF. Third VentricleG. Quadrigeminal Plate CisternH. Cerebellar VermisI. Occipital Lobe

CT SCAN..CT SCAN..

A. Falx CerebriB. Frontal LobeC. Body of the Lateral VentricleD. Splenium of the Corpus CallosumE. Parietal LobeF. Occipital LobeG. Superior Sagittal Sinus

CT SCAN..CT SCAN..

A. Falx CerebriB. SulcusC. GyrusD. Superior Sagittal Sinus

CT SCAN..CT SCAN..

Contrast enhanced CT:IV injection of contrast medium is often given because the abnormality not seen in pre contrast scans may be rendered visible following contrast enhancement (consequence of breakdown of blood brain barrier allowing contrast to enter the lesion particularly in neoplasm, infection, inflammation and certain stage of ischemia).

Also it is helpful in demonstrating blood vessels

MCAACA

Basilar arteryStraight sinus

Superior sagittal sinus

Contrast enhanced CT

CT SCAN..CT SCAN..

Sagittal reconstruction Coronal reconstruction

Computer reconstructions Computer reconstructions can in selected circumstances can in selected circumstances

be made from the axial be made from the axial sections which then sections which then provide images in coronal provide images in coronal or sagittal planes.or sagittal planes.

CT SCAN..CT SCAN..

Acute extradural hemorrhage

Bone window Brain window

fracture

The window settings are selected for The window settings are selected for the brain, but may be altered to shows the brain, but may be altered to shows the bones. the bones.

CT SCAN..CT SCAN..

fractureBone window

CT SCAN..CT SCAN..

CTA

CT angiography is helpful in diagnosis of vascular diseases and abnormalities such as stenosis, occlusion or vascular malformation

Occlusion of left middle cerebral artery

MRI..MRI..

MRI..MRI..

• No ionizing radiation No ionizing radiation • Patient preparation: Nil unless fasting for Patient preparation: Nil unless fasting for

general general • anaesthesia. anaesthesia.

• Contrast medium: GadoliniumContrast medium: Gadolinium

• Indications: Indications: strokesstrokes tumourstumours infection infection Vascular disorders Vascular disorders white matter diseasewhite matter disease some cases of traumasome cases of trauma

MRI..MRI..

Contraindications Contraindications cardiac pacemakercardiac pacemaker

Other relative Other relative Contraindications Contraindications

intraocular ferrous foreign bodyintraocular ferrous foreign bodypregnancy (1pregnancy (1stst trimester) trimester) claustrophobiaclaustrophobia

MRI..MRI..

MRI is a multiplanar technique (can produce images in Sagittal, axial and coronal planes) which is useful for assessment of extent of brain tumors and for better visualization of structures of posterior fossa and cranio-cervical junction.

MRI is a multisequential technique (can create images in T1WI, T2WI, FLAIR, gradient and other sequences).

It is possible to recognize flowing blood and therefore large arteries and veins stand out clearly without the need for contrast medium injection.

MRI..MRI..

PONSPONS

CCCC

CEREBELLUM

Sphenoid sinusSphenoid sinus

PITUTARYPITUTARY

MEDULLAMEDULLA

Spinal cordSpinal cord

clivusclivus

PonsPons

MedullaMedulla

33rdrd v v

cordcord

Cerebral Cerebral pedunclepeduncle

MRI BRAIN (CORONAL T1WI)MRI BRAIN (CORONAL T1WI)

MRI..MRI..

OPTIC CHIASMOPTIC CHIASM

Temporal horn lateral Temporal horn lateral ventricleventricle

CEREBELLAR CEREBELLAR FOLIAFOLIA

Mid brain

OPTIC TRACTOPTIC TRACTMCA

CEREBRAL CEREBRAL PEDUNCLEPEDUNCLE

Aquiduct of sylviusAquiduct of sylvius

VERMISVERMIS

MRI..MRI..

GREY GREY MATTERMATTER

WHITE WHITE MATTERMATTER

MRI..MRI..

T2WI FLAIR

MRI..MRI..

The Characteristic signal intensity of brain structures in different MRI sequences:

Grey matter

White matter

CSF

T1WI grey light dark

T2WI light dark white

FLAIR light dark dark

MR Angiography..MR Angiography..

MRA

MRACan be done without injection of contrast medium using time of flight technique.

Can be used to assess intra and extra cranial arteries for any vascular abnormalities such as stenosis, occlusion or vascular malformation.

MR Venography..MR Venography..

MRV

MRV

Can be done either with or without injection of contrast medium.

Assess venous dural sinuses superficial and deep venous system.

Can confirm presence of venous thrombosis

MRI Diffusion..MRI Diffusion..

DWI ADC map

MR diffusion

Very helpful in assessment of:

•Early brain infarction.

•Brain abscess.

•Certain types of brain tumor.

ULTRASOUND NEONATAL BRAINULTRASOUND NEONATAL BRAIN....

It is a simple and easy way to scan the head of neonates and young babies.

Not using ionizing radiation

Scanning is best done through an open fontanelle.

Little discomfort to the baby.

Readily carried out even on ill babies in intensive care units.

It has proved particular useful in detecting ventricular dilatation (hydrocephalus), intracerebral hemorrhage and congenital abnormality of the brain

ULTRASOUND NEONATAL BRAINULTRASOUND NEONATAL BRAIN....

CORONAL SAGITTAL

Stephanie Ryan, “Anatomy for Diagnostic imaging”, 2nd Edition, Pages 61-66

Jamie Weir, Peter Abraham, “Imaging Atlas of Human Anatomy” 3rd Edition, Pages 34-41

Peter Armstrong, “diagnostic imaging ”, 5th Edition, Pages (396-404)