NeuroRadiology Flashcards by Zoe Doak

What would indicate the need for brain imaging?

headache/ raised ICP
seizure
weakness
stroke
trauma
loss of conciousness/ neurological deficit
Post Op monitoring

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What are the advantages of CT scans?

Excellent bony details/spatial resolution
Fast
Compatible with emergency/ICU equipment

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What are the disadvantages of CT scans?

Only sensitive to blood EARLY in acute injury
Poor soft tissue detail
Grey and white matter show little difference in density
High radiation dose

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What shows up bright and what shows up dark on CT imaging?

Bright = More dense => bone, any metal implants

Dark = Less dense => air

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What are the advantages of MRI scanning?

Excellent contrast/soft tissue resolution
Excellent depiction of anatomy
Good for visualising marrow and cord pathologies
Multiplanar

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What are the disadvantages of MRI scanning?

Less bony detail/spatial resolution
Not compatible with pacemakers and many implants (due to magnet)
Not compatible with ICU/emergency equipments
Not as quick as CT
Patient cooperation required

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Why are different MRI sequences used and give some examples of commonly used sequences.

Multiple sets of MRI images are taken at the one time
(e.g. T1, T2 etc)

=> Different sequences use different combinations of technical parameters
=> Each sequence is unique and gives different information.

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What components of the brain enhance as “hyperintense” on T1-weighted MRI imaging?

3 Fs and 4Ms 
F: fat
F: slow flow (e.g. partially blocked vessel)
F: fluid (containing protein)
M: melanin
M: methaemoglobin (blood)
M: mineralisation (Ca/Mg etc)
M: Magnevist (gadolinium contrast)

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What components of the brain appear as “hypointense” on T1-weighted imaging?

Water
High Flow (e.g. arteries)

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What shows up as hyperintense on T2-weighted MRI imaging?

Water or any fluid collections
- oedema, demyelination, gliosis, some tumors

Fat (this can be suppressed by design)

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What shows up as hypointense on T2-weighted imaging?

Some blood products (subacute hematoma)
Mineral deposition
High flow (e.g. arteries)

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What are some of the basic sequences used in MRI and why are they used?

T1, T2,
FLAIR (Type of T2 where free water = suppressed e.g. ventricles)

T2* (gradient echo) = highlights blood

T1 (3D): Volumetric

Contrast enhancement = increases density of objects needing to be visualised

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Any structure within the blood-brain barrier resists contrast. TRUE/FALSE?

TRUE

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Why is gadolinium used as MRI contrast?

Patients are not allergic to it like iodine CT contrast

- Has many unpaired electrons which cause an MRI signal to be picked up

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What vascular pathologies would you expect to see on brain imaging?

Infarcts
Haemorrhage
Vascular anomalies

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Describe how a thrombus in a blood vessel of the brain will appear on CT?

Bright

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Why is MRI more sensitive to diagnosing stroke?

Grey and white matter differentiation on CT not good enough to outline small infarcts

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Why is CT completed first over MRI on presentation of stroke?

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Faster

Gives indication of infarct vs haemorrhage and whether pt should receive thrombolysis

An intreparenchymal bleed can break through to the ventricles. TRUE/FALSE?

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TRUE

What is a Susceptibility weighted imaging (SWI) MRI sequence used to look for?

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sensitive to venous blood
especially old venous blood that cannot be picked up on CT
=> looking for haemorrhage and iron storage

what usually causes a subarachnoid haemorrage?

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Usually due to aneurysm

How long after an IV injection of CT contrast does it show up in arteries?

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8-10s

In what type of imaging is CT contrast used?

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CT angiogram

Why are arteries and veins easy to distinguish in the brain?

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separated anatomically

=> distinct from each other in imaging

What imaging modality is used for aneurysm follow up?

MRI

Describe how a "cavernoma" (type of vascular anomaly) appears on imaging?

Popcorn appearance | Ca2+ present

MRI is more sensitive than CT for small aneurysms. TRUE/FALSE?

FALSE - CT more sensitive due to use of contrast, MRI angiography often doesnt use contrast

X-Rays are still routinely completed in trauma cases. TRUE/FALSE?

FALSE

What modality of imaging is sensitive for bone injury and ACUTE bleeding in trauma?

What structures in the brain are rather immobile if a bleed occurs and compresses them?

Falx Cerebri - quite stiff and wont initially move much with internal bleed

What is brain contusion, and where does it usually occur?

- Part of many traumatic brain injuries - Bruise of the brain tissue - associated with multiple microhemorrhages - usually occurs on underside of frontal lobe

Describe the difference between the appearance of an extradural and subdural haematoma on imaging

Extradural - biconvex, lemon-shaped and do not cross sutures | Subdural - concave, banana-shaped, crescentic, can cross sutures

What is the difference in location between intra and extra-axial neoplastic processes?

Extra-axial - outwith brain parencyhma | Intra-axial - within brain parenchyma

Intra-axial neoplastic processes are more likely to be benign. TRUE/FALSE?

FALSE extra-axial = more often benign nitra-axial = mostly malignant

Give examples of benign extra-axial tumours

meningioma pituitary adenoma dermoid/epidermoid acoustic schwannoma

Give examples of intra-axial tumours

Glioma Glioblastoma Metastases

What is a chiari malformation?

- Congenital problem - lowest part of the back of the brain extends into the spinal canal - Can put pressure on the brainstem, spinal cord, and obstruct the flow of fluid.

What is cortical dysplasia?

Migration of sensory and motor information to the outer cortex during development is impaired - grey and white matter seem "blurred" in the dysplastic areas

What is polymicrogyria?

- the brain develops too many folds (gyri and sulci) | - the folds are unusually small.

What is schizencephaly? How does it look on radiology and what can this cause?

- slits across grey and white matter from outer cerebral cortex - clefts in both hemispheres commonly have developmental delays, delays in speech and language skills, seizures, and problems with brain-spinal cord communication

How does demyelination usually affect the brain?

Occurs in white matter surrounding small veins | - demyelination occurs perpendicular to corpus callosum

What type of MRI imaging would you use to visualise demylination of the white matter?

T2 and FLAIR

Where in the brain does Herpes Encephalitis normally occur, and what does it cause in these areas?

- Temporal lobe and limbic system | - swollen neurones seen

What is CJD?

- spongiform encephalopathy of brain => degenerative Early Symptoms: - memory problems - behavioural changes - poor coordination - visual disturbances Later Symptoms: - dementia - involuntary movements - coma

NeuroRadiology Flashcards

(44 cards)