Neuroradiology Flashcards
How soon after an ischaemic stroke are signs of an acute stroke visible on non contrast CT brain?
6 hours
What are the signs of an acute ischaemic stroke on CTB? (3)
loss of grey/white differentiation (hypodense area, but not as hypodense as water) sulcal effacement (due to swelling of cerebral parenchyma) Linear hyperdensity (may be an affected artery thromboembolism)
What is the most sensitive imaging test for cerebral infarction?
DWI (diffusion weighted imaging) MRI- diffusion restriction within infarcted tissue
Should you do an LP in someone with sudden onset severe headache?
No- headache could be due to raised ICP and LP might then cause them to cone
What does a subarachnoid haemorrhage look like on CT?
Hyperdense blood (white)- may be in a star pattern (suprasellar cisterns) and in sulci
May be widening of ventricles (hydrocephalus)
What is the most sensitive test for a cerebral aneurism?
Cerebral CT angiogram and subsequent digital subtraction angiogram
What are the complications of SAH? (3)
vasospasm–> infarction, hydrocephalus, intracerebral haemmhorage
Wjhat is post ictal hemiparesis also known as?
Todd’s paresis
What does an old infarct (>4 weeks) look like on non contrast CT?
Hypodense (black) with no mass effect, oedema, fresh haemmhorage
What is the most common mechanism for ischaemic stroke?
Emboli from carotids/ heart
What does an intracerebral haemorrhage look like on CT?
Hyperdesne lesion within the brain parechyma
What are the 3 most common sites of intracerebral haemorrhage caused by hypertension?
basal ganglia, brain stem, cerebellum
What investigations are used for MS (2 most important)?
LP–> CSF looking for oligoclonal bands (paraprotein from myelin breakdown)
MRI–> demyelinating plaques: multiple hyperintense lesions on T2 and FLARE (CSF supressed). Plaques often abut the ventricles.
What t=do MS plaques look like on TI with IV contrast
Ring enhancement- active plaque with breakdown of BBB. No ring enhancement= old plaque or other lesion.
Subacute onset (over a few days) of UMN weakness and signs of a unilateral upper limb accompanied by no LL signs- ddx?
- neoplasm (primary of mets)
- deymyelinating disease
- cerebrovascular disease (less likely given time course)
What is vasogenic cerebral oedema?
What causes vasogenic oedema?
What is the appearance of vasogenic oedema on CT/MRI?
Vasogenic cerebral oedema refers to a type of cerebral oedema in which the blood brain barrier (BBB) is disrupted (c.f. cytotoxic cerebral oedema where BBB is intact). It is an extracellular oedema which mainly affects the white matter, through leakage of fluid out of capillaries.
It is most frequently seen around brain tumours (both primary and secondary) and cerebral abscesses, although some vasogenic oedema may be seen around maturing cerebral contusion and cerebral haemorrhage.
Oedema extends in a ‘finger like’ fashion into the cortex, and is hyperintense on FLAIR MRI
What is cytotoxic cerebral oedema?
What causes cytotoxic oedema?
What is the appearance of cytotoxic oedema on CT/MRI?
Cytotoxic cerebral oedema refers to a type of cerebral oedema, most commonly seen in cerebral ischaemia, in which extracellular water passes into cells, resulting in their swelling- intracerebral oedema. (BBB intact)
Low diffusion on MRI DWI
What does IV contrast enhancement of a brain lesion indicate?
What are 3 possible lesions?
Breakdown of BBB
Tumour, infection, demyelination.
What are the 4 most common sources of mets to the brain?
lung, breast colon, melanoma
What 2 things could hyperdensity on CT brain represent?
Blood or calcium
Which kidn of brain tumour is calcification most commonly seen in?
meningioma
