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Flashcards in Neuroradiology Deck (29)
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1
Q

CT is good at viewing what?

A

bony details, spatial resolution

poor soft tissue detail and contrast resolution

2
Q

is CT sensitive to a bleed?

A

only if very recent bleed

cannot view old blood

3
Q

what shows as bright white on CT?

A
dense materials (bone etc)
less dense (e.g air) shows as black
4
Q

how do grey/white matter appear on CT?

A

difficult to differentiate as similar density
- must view image within specific range of densities to see any difference
white matter generally darker (only on T2???)

5
Q

benefits of MRI?

A

good contrast/soft tissue resolution
good anatomy depiction
marrow and cord pathology
multiplanar capacity

6
Q

drawbacks of MRI?

A

less bony detail
less spatial resolution
not compatible with pacemakers and other implants (magnetic force)
not compatible with most ICU/emergency equipment
not as quick as CT, needs patient cooperation

7
Q

how does MRI work?

A

different sequences using a combination of technical parameters
each sequence is unique and gives different information
overall MRI assessment involves correlation of all sequences

8
Q

basic sequences in MRI?

A
T1
T2
FLAIR
T2 (gradient echo)
T1 (3D) volumetric
contrast enhancement
9
Q

what shows as bright white in T1?

A

fat and 4 Ms

  • fat (if not purposely suppressed)
  • methemoglobin (subacute hematoma)
  • mineral deposition
  • melanin (melanoma)
  • mush (highly proteinaceous fluid)
  • contrast material (gadolinium)
10
Q

what shows as dark on T2?

A

some blood products (subacute hematoma)
mineral deposition
paucity of water or mobile protons
high flow (arterial flow voids)

11
Q

bright on T2?

A

more water/less tissue (e.g fluid collections, oedema, demyelination, some tumours etc)
fat

12
Q

dark on T1?

A

water
paucity of mobile protons (air, cortical bone)
high flow (arterial “flow voids”)

13
Q

best imaging for a stroke?

A

CT (generally)

14
Q

what may be seen on CT in acute stroke?

A

thrombosed vessel (dense area/line)
lack of grey/white matter differentiation
darker blob where fluid is accumulating after some time

15
Q

stroke/infarct after some time has passed?

A

more fluid accumulates and density gets lower in area of brain causing it to become darker

16
Q

how does infarct appear?

A

white on CT

17
Q

imaging for haemorrhage?

A

CT is best but only sensitive in the initial stages
will not pick up any bleed after around 48 hours?
then an MRI will be used

18
Q

how can intracranial arteries (potential aneurysms etc) be viewed?

A

inject contrast and then CT

19
Q

SWI?

A

most sensitive MRI sequence for blood

susceptibility weighted imaging

20
Q

clotting of dural venous sinuses?

A

back pressure of blood causes increased intracranial pressure
can lead to vessel rupture etc intracranially

21
Q

cavernoma?

A

type of vascular malformation which can cause bleeding (usually not a massive bleed, can just bleed from time to time)
causes popcorn head appearance on imaging

22
Q

hallmark of trauma imaging in the head?

A

CT

23
Q

principle of trauma imaging?

A

skull is closed cavity with no extra space so if haematoma or swelling occurs, herniation/shifts of brain tissue will occur

24
Q

extradural vs subdural haematoma?

A
extradural = convex shape
subdural = concave shape
25
Q

most common extra-axial brain tumour?

A

meningioma (benign)

most extra-axial tumours are benign

26
Q

chiari malformation?

A

where the lower part of the brain extends into the spinal canal

27
Q

commonest inflammatory condition in the brain?

A

demyelination (MS)
affects white matter
scattered lesions?

28
Q

commonest cause of infection in the brain?

A

herpes encephalitis

29
Q

CJD?

A

Creutzfeldt–Jakob disease

degenerative brain disease which can be transmitted through exposure to affected brain or nervous tissue