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radiography > CT > Flashcards

CT Flashcards

1
Q

CIrcle of willis artery and location

  • ACA
  • MCA
  • PCA
  • ICA
  • SCA
A
  • ACA: anterior cerebral artery (pointing anteriorly from circel)
  • Acom artery (anterior communicating artery ) - located between the two ACA
  • MCA: middle cerebral artery - outer aspect of circle
  • pcom artery (posterior communicating artery) - located between MCA and PCA
  • PCA: posterior cerebral artery: posterolateral aspect of circle
  • ICA: internal carotid artery: interior aspect of circle at level of the MCA
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2
Q

Subarachnoid haemorrhage

- (symptoms?)

A
  • bleeding into the subarachnoid space

symptoms:

  • sudden severe headache (thunderclap headache)
  • photophobia
  • vomiting
  • drowsiness

can be a result of trauma but mainly vascular abnormalitiy

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3
Q

CT head pathology

A
  • is there symmetry - has midline shift occured?

-

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4
Q

Infarct (tissue death)

A
  • appears as hypodense (dark) on a ct due to the development of odema caused by breakdown of the blood brain barrier
  • not much odema is seen during the hyhperacute phase
  • A thrombolytic agent is used to break down clot (thrombus) - should be given within 4 1/2 hourse of admission
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5
Q

blood appearance on CT image

A

acute blood (1-2 days): appears as bright white - HYPERDENSE - as it contains highly dense globin

sub-actue (1-14 days): iso-dense - same colour as surroundings

chronic (>14 days): hypodense - black

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6
Q

what is the MCA sign?

A
  • a hyperdensity in the middle cerebral artery on NON-CONTRAST ct head
  • it is a visualisation of the clot/thrombus
  • earliest sign of a MCA infarction (90 minutes after)
  • the longitudinal equivalent of the MCA dot sign
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6
Q

what is the MCA sign?

A
  • a hyperdensity in the middle cerebral artery on NON-CONTRAST ct head
  • it is a visualisation of the clot/thrombus
  • earliest sign of a MCA infarction (90 minutes after)
  • the longitudinal equivalent of the MCA dot sign
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7
Q

How to describe a CT lesion

A
  • hypo/iso/hyper dense?
  • shape/size/symmetry?
  • position
  • contours - e.g. well defined, ill-defined
  • time after the episode
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8
Q

Haemorrhage

A
  • an acitve bleed
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9
Q

Haematoma

A
  • blood clot or build up of blood
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10
Q

contusion

A
  • bruising caused from brain hitting of inside of skull resulting in little bleeds at multiple sites of the brain
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11
Q

Describe an extradural haematoma vs a subdural haematoma

A

extradural: blood is above the dura. The dura links to the sutures of the skull. THe blood can only go in the space between the sutures. Bulges into the brain
subsural: blood is below the dura. The blood stretches along the line of the brain as it is not stopped by the sutures

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12
Q

Low grade tumour

A
  • small amount of associated odema
  • when given contrast, there is only minimal enhancement

e.g. low grade glioma

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13
Q

High grade tumour

A
  • big area of odema
  • large enhancement with contrast
  • often has different densities within the tumour
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14
Q

Primary or metastatic lesion?

A
  • primary lesions tend to be singular
  • metastases tend to multiple
  • metastases: odema is a lot bigger than the lesion
  • metastases have peripheral/ring enhancement
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15
Q

what does the 4th ventricle look like and its location?

A
  • looks like a mouth (sylvian fissures look like eyes) and it located posterior of the brain, in the midline (posterior of where the foramen magnum would be)
  • sits behind the pons
16
Q

What is the falx cerebri?

A
  • crescent shaped dura that separates the two hemishperes. runs down the midline of the brain
17
Q

what are the sylvian fissures?

A
  • separate the temporal lobe (below) from the frontal and pratietal lobes (above)
  • look like eyes of the face at the lateral aspects of the brain
18
Q

what does the third ventricle look like?

A
  • appears as a vertical line running up the midline of the brain - appears hypo dense as it is full of csf
19
Q

lateral ventricles

  • (what do they look like?)
  • (any areas of hyper/hypodensity?)
A
  • two lateral ventricles, left and right with anterior and posterior horns
  • areas of hyperdensity at the posterior horn
  • this hyperdensity is calcificaiton within the choroid plexus - the area where CSF is produced
20
Q

what is cerebral vasospasm?

A
  • blood vessels spasm causing vasoconstriction which can lead to tissue ischemia and necrosis
  • typically appears 4-10 days after a SAH - patients need to be monitored for up to 21 days after SAH
  • after a SAH,white blood cells enter teh subarachnoid space to try and clear the blood but they get stuck there. when they die they release endothelins which cauuse vasoconstriction and vasospasm
21
Q

what is arteriovenous malformation?

A
  • abnormal connection between arteries and veins - bbypasses teh capillary system
  • asymptomatic
  • thought to be hereditary

radiography (15 decks)

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