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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.

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Presentation on theme: "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."— Presentation transcript:

1 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 to stenosis. aneurysm & AVM aneurysm & AVM

2 Imaging 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. Inconstant Metopic suture. Inconstant

3 Lytic & sclerotic lesions in the skull Lytic lesions Metast. & M.M. Metast. & M.M. Geographic skull in histiocytosis X. Geographic skull in histiocytosis X. Sclrotic lesions Localized sclerosis… metastases Localized sclerosis… metastases

4 CT Brain Normal CT Normal CT Abnormal CT cardinal signs Abnormal CT cardinal signs -abnormal tissue density high density…recent hge, calcified and contrast enhancement high density…recent hge, calcified and contrast enhancement low density….neoplasm, infarct, oedema low density….neoplasm, infarct, oedema

5 Abnormal CT…cont. Mass effect..compressed or displaced Mass effect..compressed or displaced lateral ventricles lateral ventricles Midline shift Midline shift Dilatation of ventricular system Dilatation of ventricular system -CT with contrast; CT angio -CT with contrast; CT angio

6 MRI of brain Multiplanar capability….extent of tumor. Multiplanar capability….extent of tumor. esp. for post. Fossa & craniovertebral junction. esp. for post. Fossa & craniovertebral junction. Disadvantage; inability to show calcification and bone details long scan time long scan time difficulty in monitoring critical patients difficulty in monitoring critical patients

7 MRI Brain Contrast Contrast Gadolinium Gadolinium MRA severe stenosis & aneurysm MRV venous sinuses

8 MRI Brain It is more often possible to make a specific diagnosis with MRI than CT. It is more often possible to make a specific diagnosis with MRI than CT. Demyelinating plaques of MS Demyelinating plaques of MS AVM AVM

9 Neurosonography Hydrocephalus Hydrocephalus Hemorrhage Hemorrhage Congenital abnormalities. Congenital abnormalities.

10 Brain Tumors Glioma Glioma Solitary irregular mass Solitary irregular mass surrounded by edema surrounded 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 calcify may calcify most show partial enhancement. most show partial enhancement. may be ring enhancement. may be ring enhancement. Low in T1, high in T2 Low in T1, high in T2

11 Metastases Metastases may be of high or low density. may be of high or low density. surrounded by edema surrounded by edema typically multiple typically multiple a solitary metast. could not be diff. from a solitary metast. could not be diff. from a primary neither by CT nor by MRI a primary neither by CT nor by MRI

12 Meningioma Meningioma arise from meninges of the vault, falx & tentorium. arise from meninges of the vault, falx & tentorium. commonest sites are parasagittal region over the cerebral convexities & sphenoid ridge. commonest sites are parasagittal region over the cerebral convexities & sphenoid ridge. Slightly hyperdense on native CT Slightly hyperdense on native CT marked enhancement marked enhancement Acoustic neuroma; in the CPA near IAM.

13 Pit. Tumors: Pit. Tumors: microadenoma < 10mm microadenoma < 10mm macroadenoma.> 10mm macroadenoma.> 10mm MRI

14 Cerebral infarction & hemorrhage Cerebral infarction & hemorrhage Clinically similar CT is the initial exam. Hge….high density surrounded by edema. May be SAH or intraventricular. In Infarction ….CT normal initially. MRI diffusion Weighted Images.

15 SAH usually due to rupture aneurysm. SAH usually due to rupture 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. AVM may present with Hge….CT can show the AVM esp. with contrast. But MRI is better even without contrast. But MRI is better even without contrast.

16 Abscess Abscess Low density with ring enhancement Low density with ring enhancement

17 Head Injury: Head Injury:Fractures # more translucent # may branch abruptly Suture in known anatomical positions. Depressed #....dense. EDH can result from # through MMA groove.

18 CT in head injury CT should be done when there is: -deterioration in the conscious level. -worsening of neurological deficits. Extracerebral lesions -EDH.. biconvex. Associated with # High density for 2Wks. High density for 2Wks. After 3-4Wks…..hypodense Isodense in between. -SDH…….concavoconvex

19 Fractures of the base & vault are easily seen in bone window Intracerbral lesions: -Edema- homogenous low density. -Contusions- patchy low density areas -Intracerebral hematoma Severe head injury can exist with no abnormal CT

20 20 Cerebral infarction with mass effect

21 21 Intracerebral hemorrhage (hyperdense lesion in CT scan)

22 22 Acute epidural hematoma Acute epidural hematoma (lenticular shaped clot)

23 23 Subarachnoid hemorrhage (hyperdensity in Sylvain fissures and interhemispheric fissures in CT scan)

24 Subdural hematoma (crescentic collection over the convexity of the hemisphere) 24

25 25 MCA aneurysm

26 26 Meningioma

27 Brain abscess 27

28 28 Meningioma

29 29 Pituitary adenoma

30 Multiple osteolytic lesions (multiple myeloma) 30

31 31 Multiple brain secondaries


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