Skull & Brain Imaging Techniques Plain……..M.M. before MRI for intra-occular metalic FB intra-occular metalic FB CT & MRI …standard investig. US Angiography….Limited.

Skull & BrainSkull & BrainImaging TechniquesImaging Techniques

Plain……..M.M. before MRI for Plain……..M.M. before MRI for

intra-occular metalic intra-occular metalic FBFB

CT & MRI …standard investig.CT & MRI …standard investig.

USUS

Angiography….Limited to Angiography….Limited to stenosis. stenosis.

aneurysm & aneurysm & AVMAVM

Imaging TechniquesImaging Techniques

Plain ….Plain …. Normal….inner & outer tables (compact)Normal….inner & outer tables (compact) Diploic space ( spongy bone )Diploic space ( spongy bone ) Sutures remain visible even Sutures remain visible even after fusion. after fusion. Metopic suture. InconstantMetopic suture. Inconstant

Lytic & sclerotic lesions in the Lytic & sclerotic lesions in the skullskull

Lytic lesionsLytic lesions Metast. & M.M.Metast. & M.M. Geographic skull in histiocytosis X.Geographic skull in histiocytosis X.

Sclrotic lesionsSclrotic lesions

Localized sclerosis… metastasesLocalized sclerosis… metastases

CT BrainCT Brain

Normal CT Normal CT Abnormal CT cardinal signsAbnormal CT cardinal signs

-abnormal tissue density-abnormal tissue density

high density…recent hge, calcified high density…recent hge, calcified and contrast enhancementand contrast enhancement

low density….neoplasm, infarct, low density….neoplasm, infarct, oedema oedema

Abnormal CT…cont.Abnormal CT…cont.

Mass effect ..compressed or displacedMass effect ..compressed or displaced lateral ventricleslateral ventricles Midline shiftMidline shift

Dilatation of ventricular systemDilatation of ventricular system -CT with contrast; CT angio-CT with contrast; CT angio

MRI of brainMRI of brain

Multiplanar capability….extent of Multiplanar capability….extent of tumor.tumor.

esp. for post. Fossa & craniovertebral esp. for post. Fossa & craniovertebral junction.junction.

Disadvantage; inability to show Disadvantage; inability to show calcification and bone details calcification and bone details

long scan timelong scan time

difficulty in monitoring critical patientsdifficulty in monitoring critical patients

MRI BrainMRI Brain

ContrastContrast

GadoliniumGadolinium

MRA severe stenosis & aneurysmMRA severe stenosis & aneurysm

MRV venous sinusesMRV venous sinuses

MRI BrainMRI Brain

It is more often possible to make a It is more often possible to make a specific diagnosis with MRI than CT.specific diagnosis with MRI than CT.

Demyelinating plaques of MSDemyelinating plaques of MSAVM AVM

NeurosonographyNeurosonography

HydrocephalusHydrocephalusHemorrhageHemorrhageCongenital abnormalities.Congenital abnormalities.

Brain TumorsBrain Tumors GliomaGlioma

Solitary irregular massSolitary irregular mass

surrounded by edemasurrounded by edema

may compress or displace ventricle.may compress or displace ventricle.

usually hypodense usually hypodense

may be hyper or mixed.may be hyper or mixed.

may calcifymay calcify

most show partial enhancement.most show partial enhancement.

may be ring enhancement.may be ring enhancement.

Low in T1 , high in T2Low in T1 , high in T2

MetastasesMetastases

may be of high or low density.may be of high or low density.

surrounded by edemasurrounded by edema

typically multiple typically multiple

a solitary metast. could not be diff. a solitary metast. could not be diff. fromfrom

a primary neither by CT nor by MRIa primary neither by CT nor by MRI

MeningiomaMeningioma arise from meninges of the vault, falx arise from meninges of the vault, falx

& tentorium.& tentorium. commonest sites are parasagittal commonest sites are parasagittal

region over the cerebral convexities & region over the cerebral convexities & sphenoid ridge.sphenoid ridge.

Slightly hyperdense on native CTSlightly hyperdense on native CT marked enhancementmarked enhancement

Acoustic neuroma;Acoustic neuroma; in the CPA near in the CPA near IAM.IAM.

Pit. Tumors:Pit. Tumors:

microadenoma < 10mmmicroadenoma < 10mm

macroadenoma.> 10mmmacroadenoma.> 10mm

MRIMRI

Cerebral infarction & hemorrhageCerebral infarction & hemorrhage

Clinically similarClinically similar

CT is the initial exam.CT is the initial exam.

Hge….high density surrounded by Hge….high density surrounded by edema.edema.

May be SAH or intraventricular.May be SAH or intraventricular.

In Infarction ….CT normal initially.In Infarction ….CT normal initially.

MRI diffusion Weighted Images.MRI diffusion Weighted Images.

SAH SAH usually due to rupture usually due to rupture aneurysm.aneurysm.

CT is the best initial exam.CT is the best initial exam.

The large aneurysms are seen by CT.The large aneurysms are seen by CT.

MRA can show smaller aneurysms.MRA can show smaller aneurysms.

Arteriography is the best.Arteriography is the best.

AVMAVM may present with Hge….CT can may present with Hge….CT can show the AVM esp. with contrast.show the AVM esp. with contrast.

But MRI is better even without But MRI is better even without contrast.contrast.

AbscessAbscess

Low density with ring enhancementLow density with ring enhancement

Head Injury:Head Injury:FracturesFractures# more translucent# more translucent# may branch abruptly# may branch abruptly

Suture in known anatomical positions.Suture in known anatomical positions.Depressed #....dense.Depressed #....dense.

EDH can result from # through MMA groove.EDH can result from # through MMA groove.

CT in head injuryCT in head injuryCT should be done when there is:CT should be done when there is:-deterioration in the conscious level.-deterioration in the conscious level.-worsening of neurological deficits.-worsening of neurological deficits.

Extracerebral lesionsExtracerebral lesions-EDH.. -EDH.. biconvex. Associated with #biconvex. Associated with # High density for 2Wks.High density for 2Wks.After 3-4Wks…..hypodenseAfter 3-4Wks…..hypodenseIsodense in between. Isodense in between.

-SDH-SDH…….concavoconvex…….concavoconvex

Fractures of the base & vault are easily Fractures of the base & vault are easily seen in bone windowseen in bone window

Intracerbral lesions:Intracerbral lesions:-Edema- -Edema- homogenous low density.homogenous low density.-Contusions- -Contusions- patchy low density areaspatchy low density areas-Intracerebral hematoma-Intracerebral hematoma

Severe head injury can exist with no Severe head injury can exist with no abnormal CTabnormal CT

2020

Cerebral infarction with mass effectCerebral infarction with mass effect

2121

Intracerebral hemorrhageIntracerebral hemorrhage (hyperdense lesion in CT scan)(hyperdense lesion in CT scan)

2222

Acute epidural hematomaAcute epidural hematoma(lenticular shaped clot)

2323

Subarachnoid hemorrhageSubarachnoid hemorrhage(hyperdensity in Sylvain fissures and (hyperdensity in Sylvain fissures and interhemispheric fissures in CT scan)interhemispheric fissures in CT scan)

Subdural hematomaSubdural hematoma((crescentic collection over the convexity of the crescentic collection over the convexity of the

hemispherehemisphere))

2424

2525

MCA aneurysm MCA aneurysm

2626

MeningiomaMeningioma

Brain abscessBrain abscess

2727

2828

MeningiomaMeningioma

2929

Pituitary adenomaPituitary adenoma

Multiple osteolytic lesionsMultiple osteolytic lesions(multiple myeloma)(multiple myeloma)

3030

3131

Multiple brain secondariesMultiple brain secondaries