Review to CNS radiology including Special Senses

Bisher Al-HalabiCollected from different resources

and handouts

Outline

• Theory and introduction• Spine and content• Brain stem radiology• Cortex and skull - Blood supply• SOL DDx and examples• SS• Questions…

1) Theory and introduction

• Need to know what to use, when• Need to know advantage over disadvantage• Need to know what appears how• Need to know conditions• I will present FEW cases only• Theory and understanding more important

1) Plain X-ray

• Superficial clear bones• Lowest radiation (compared to CT)• Has limited function except for clear

superficial skull fractures• Used in spinal skeleton injury• Multiple would construct a CT

2) CT • CT is ideal to demonstrate the fractures and deep

bones/ small bones that will not appear on plain x-ray

• Constructed from different angular x-rays• Used to see tissue relation to bone (anatomy )• Used in SAH, ICH, etc• Used over MRI as faster to appoint• In SC fracture and relation of fragments to the

cord.• High amount of radiation X pregnant

When??- Brain infarction, hemorrhage (intracranial, subdural,extradural)

- SAH, brain trauma, tumor

- Spine fracture (stable vs unstable)

- Lumbar disc, bone tumor

- Contrast can be used to check on cervical & dorsal disc as well as spinal canal pathology (CT Myelogram)

1-First About CT language -Increased whiteness on a CT scan is referred to as -hyperdense or high

attenuation.Causes of hyperdensities include: Calcification Acute hemorrhage Ossification Contrast

2-Increased darkness on a CT scan is referred to as hypodense or low attenuation.Causes of hypodensities include: Air FatNote that air appears darker than fat on a CT scan.

2--CT Without Contrast When to Order

This is usually the first test performed in an emergency setting. It is excellent at identifying blood.

--AdvantagesIf patient is stable, there are relatively no contraindications for ordering this test. It is a fast exam that can be completed in seconds.

-DisadvantagesDue to bony artifact, it is difficult to visualize abnormalities in the posterior fossa and brain stem.

3-CT with ContrastIf no abnormality is seen without a contrast, then a scan with contrast could

be ordered to see if there is identifi able pathology. Contrast will help identifytumor, abscess, arteriovenous (AV) malformation, and aneurysm.

-AdvantagesIf a lesion enhances with contrast, then the blood-brain barrier is compromised.This can be seen in tumors, abscesses, and arteriovenous malformation.

-DisadvantagesContrast will obscure an acute bleed. Thus, in an emergency setting, it is importantto obtain a CT without contrast fi rst

Contrast

• Anaphylaxis• Renal faluire

3)MRI• Resonance built on magnetic basesMultiplanar Imaging , Various Sequences, No Radiation.• T1-

• white matter to white, • gray matter to gray, • cerebrospinal fluid (CSF) dark.

• The contrast of white matter, gray matter and cerebrospinal fluid is reversed using T2 or T*2 imaging,

Indication• Investigation of choice of almost all

neuropathology, • great details in brain & spine.• Brain tumors, MS• Congenital, inflammatory• pathology, cranial nerves • MRA for Vascular abnormality.• Differentiate between extradural, intradural,• extramedullary and intramedullary pathology.

•T1 for highly detailed anatomy•T2 for abnormal

tissue

Sagital

2) Spine and content

• We will do SOL later

T1 T2 Contrast

Tuberculous spondylodiscitis at the level L2/L3Tuberculous spondylodiscitis at the level L2/L3

3) BS

• Check for cavernous sinus disease• Myelination disorders• Tumors

4) Stroke & BS

• Just a reminder• The circle of Willis comprises the following arteries:• Anterior cerebral artery (left and right)• Anterior communicating artery• Internal carotid artery (left and right)• Posterior cerebral artery (left and right)• Posterior communicating artery (left and right)• The basilar artery and middle cerebral arteries, though

they supply the brain, are not considered part of the circle.

Some theory again

The modality of choice is computed tomography(CT scan) of the brain. This has a high sensitivity and will correctly identify over 95% of cases—especially on the first day after the onset of bleeding.Magnetic resonance imaging (MRI) may be more sensitive than CT after several days

Large Arteries:- Within the known territory of a major vessel, middle, posterior, anterior and may include small arteries.

• Small Arteries:- ( Lacunar infarcts) Basal ganglia and internal capsule, Thalamus, Pons, Deep white matter

CT Findings• Area of decreased density involving the white and

gray matters (vs tumor)• As early as 6 hours but usually after 24 hrs• Mass effect that decreases with time. Effacement of

sulci.• Brain edema may cause Brain herniation.• The density of the lesion gets lower over 4 weeks

until similar to CSF with volume loss.

MRI• Low on T1 and high signal on T2

• Less sensitive in detecting hemorrhage in infarction

• Typical parenchymal enhancement with contrast after a week

--T1 images show fat as a white or bright signal, whereas water (or cerebrospinal fluid [CSF]) is dark.

--On a T2 image, fat is dark, and blood, edema, and CSF appear white

Distribution of the cerebral arteries

Anterior cerebral artery Middle cerebral artery

Posterior cerebral artery

Superolateral surface of the cerebral hemisphere

Medial surface of the cerebral hemisphere

Posterior cerebral artery

Anterior Cerebral artery

Deep territory of the middle cerebral artery

Superficial anterior (superior) territory of the middle cerebral artery.

Superficial posterior (inferior) territory of the middle cerebral artery

Hemorrhagic Infarcts

• Due to re perfusion• Due to major embolism and in patients on anti coagulants• Absence of blood on initial imaging• In the center or at the margin• Contraindication to anticoagulants treatment• CT- space occupying high density area• MRI – High signal on T1, Low on T2

CT BRAINA-- focally decreased density (darker than normal) due to stroke, edema, tumor,

surgery, or radiation B-- increased focal density (whiter than normal) on a noncontrasted scan in ventricles

(hemorrhage) in parenchyma (hemorrhage, calcium, or metal) in dural, subdural, or subarachnoid spaces (hemorrhage)

C- increased focal density on contrasted scan , tumor , stroke , abscess or cerebritis aneurysm or arteriovenous malformation (AVM)

D- asymmetrical gyral pattern , mass or edema (causing effacement of sulci) atrophy (seen as very prominent sulci)

E- midline shift F- ventricular size and position (look at all ventricles) G- sella for masses or erosion H- sinuses for fluid or masses I- soft tissue swelling over skull J- bone windows for possible fracture

5) SOL

• Appearance depend on content • Over all… tumors etc.. High on T2 low on T1

Cervical GangliogliomaT1 T2T1+C

Intra-operativeT1+C

Lesions of The Spinal Canal.

1.Extradura Extra-medullary

2.IntraduralExtra-medullary

3.IntraduralIntra-medullary

Disc- herniation- infection (TB) Bone tumor- Epidural

haemorrhage- Epidural abscess - Schwannoma

- Meningioma- Epindymoma- Drop metastasis

- Glioma

5) SOL of brain

Extra-Axial• Extra-Dural Haemmorage• Arachnoid cyst• Intradural Haemmorage• Intradural Abscess• Meningioma• Schwanoma• Dermoid/ epidermoid leasions

Intra-Axial• Cerebral Haematoma• Tumor (Glioma,

Metastasis, Medulloblastoma, lymphoma)

• Abscess• Tuberculoma, sarcoid.

Acute Intra-dural Hematoma

High density, crescent shaped hematoma (arrowheads) overlying the right cerebral hemisphere. Note the shift of the normally midline septum pellucidum due to the mass effect arrow.

Chronic Intra-dural Haematoma

Crescent shaped chronic subdural hematoma (arrowheads). Notice the low attenuation due to reabsorbtion of the hemorrhage over time

Extra-dural Haematoma

Biconvex extradural hematoma (arrowheads),deep to the parietal skull fracture (arrow).

Intracerebral Haemorrhage

Ring – enhancing contrast on T1 -DDX

• malignant tumors• high-grade glioma• glioblastoma multiforme• Metastasis (lung or breast)

• Nonneoplastic • intracerebral abscesses (toxoplasmosis+fungal) • demyelinating and reactive/resorptive lesions (acute

inflammatory demyelination, • resolving hematoma or infarction, radiation necrosis) • parasitic lesions (cysticercosis cyst, pork tapeworm).

6) SS – ear IMAGING - MODALITIES

• Plain X-ray has limited use due to thickness of the Petrous bones

• Computerized Tomography – CT

– Imaging modality of choice - narrow CT slices (1.0 -1.5mm) for the demonstration detailed bony anatomy

– Axial and Coronal series

• MRI is best for demonstration of soft tissue and nerves

Acoustic neuroma

2009 Phase 2 Integumentary systemENT

6) SS- eyeClassification of orbital lesions

Ocular lesion or non-ocular i.e. is it involving the globe or involving the structures outside the globe.Non -ocular lesion,

• Intraconal space, i.e. within the space bounded by the cone formed by the extraocular muscles, •Conal -In the muscles •Extraconal – Outside the muscles

Ocular lesions

• Specific pathologies :

• Rupture

• Hemorrhage– Vitreous– Retinal

• Infection:

• Retinal detachment

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Non-ocular - Intra-conal

The intraconal space is marked by arrows and is located within the muscle cone It contains the optic nerve, vessels and cranial nerves III, IV

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Extraconal space• The extraconal space is the area

outside the muscle cone. • Extraconal space pathology: • Abscess due to sinusitis • Schwannoma of the V1 and V2

branches of the trigeminal nerve • Bone lesions:

– Fibrous dysplasia of the sphenoid wing

– Metastases – Multiple myeloma

•

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Orbital trauma Indications

• CT – Is the modality of choice - Gives very good bony detail

• Plain x-ray will appear normal!!!• Evidence of fracture on clinical examination• Limitation of eye movement• Decreased visual acuity in setting of trauma• Severe pain• Difficult examination due to soft tissue swelling

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ORBITAL TUMORS

• Usually presents with exolphalmos or proptosis

• Eye displacement due to tumor location CT shows tumor and associated bone destruction if present

• MRI - gives excellent soft tissue demonstration

• Any questions???