Neuroradiology

Question 1

CT is good at viewing what?

Answer 1

bony details, spatial resolution

poor soft tissue detail and contrast resolution

Question 2

is CT sensitive to a bleed?

Answer 2

only if very recent bleed

cannot view old blood

Question 3

what shows as bright white on CT?

Answer 3

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

Question 4

how do grey/white matter appear on CT?

Answer 4

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???)

Question 5

benefits of MRI?

Answer 5

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

Question 6

drawbacks of MRI?

Answer 6

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

Question 7

how does MRI work?

Answer 7

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

Question 8

basic sequences in MRI?

Answer 8

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

Question 9

what shows as bright white in T1?

Answer 9

fat and 4 Ms

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

Question 10

what shows as dark on T2?

Answer 10

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

Question 11

bright on T2?

Answer 11

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

Question 12

dark on T1?

Answer 12

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

Question 13

best imaging for a stroke?

Answer 13

CT (generally)

Question 14

what may be seen on CT in acute stroke?

Answer 14

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

Question 15

stroke/infarct after some time has passed?

Answer 15

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

Question 16

how does infarct appear?

Answer 16

white on CT

Question 17

imaging for haemorrhage?

Answer 17

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

Question 18

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

Answer 18

inject contrast and then CT

Question 19

SWI?

Answer 19

most sensitive MRI sequence for blood

susceptibility weighted imaging

Question 20

clotting of dural venous sinuses?

Answer 20

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

Question 21

cavernoma?

Answer 21

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

Question 22

hallmark of trauma imaging in the head?

Answer 22

CT

Question 23

principle of trauma imaging?

Answer 23

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

Question 24

extradural vs subdural haematoma?

Answer 24

extradural = convex shape
subdural = concave shape

Question 25

most common extra-axial brain tumour?

Answer 25

meningioma (benign)

most extra-axial tumours are benign

Question 26

chiari malformation?

Answer 26

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

Question 27

commonest inflammatory condition in the brain?

Answer 27

demyelination (MS)
affects white matter
scattered lesions?

Question 28

commonest cause of infection in the brain?

Answer 28

herpes encephalitis

Question 29

CJD?

Answer 29

Creutzfeldt–Jakob disease

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