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Phase 3B Radiology > Brain imaging > Flashcards

Flashcards in Brain imaging Deck (6)
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1
Q

Hypodense lesion with ring enhancement (increased radio-opacity) on contrast CT

A

Suggestive of abscess (central necrosis and peripheral inflammation - increased vascularisation = increased enhancement on contrast)

2
Q

CT head.

a) Normal calcified structures in the brain
b) Calcified structures appear what colour on CT?
c) Acute bleed appears what colour on CT?
d) How to view a skull fracture on CT head?

A

a) Pineal gland, choroid plexus (in ventricles)
b) White
c) White
d) Bone window (rather than brain window)

3
Q

Loss of grey-white matter differentiation.

a) typical of…?
b) which itself may be caused by…?

A

a) Oedema

b) Hypoxia (cardiac arrest), infarction

4
Q

Interpreting CT head

blood, bone, symmetry

A

Blood - hyperdense (WHITE) lesions; look at shape of bleed (convex, concave, death star)
- old blood is darker

Bone - skull fracture

Symmetry - tissue ischaemia, sulcal effacement, ventricular compression / midline shift (mass effect)

5
Q

Hounsfield units (HU).

a) What are they?
b) Colour on CT relative to HU value
c) Give the HU for:
- Air
- Fat
- Water
- CSF
- White matter
- Grey matter
- Fresh blood
- Old blood
- Bone/ calcification

A

a) Measure of radiodensity of matter (used in CT)
b) Very negative = black (e.g. air); very positive = white (e.g. bone)

c) Air = -1000, 
Fat = -70, 
Water = 0, 
CSF = 10, 
White matter = 30, 
Grey matter = 45, 
Fresh blood = 100, Old blood = 20, 
Bone/calcification = 1000
6
Q

What would be the typical appearance of the following on CT head:

a) Acute intracerebral haemorrhage
b) Acute extradural haemorrhage
c) Subacute subdural haemorrhage
d) Acute intracerebral infarct

A

a) Area of high density (fresh blood - white), possibly surrounded by area of lower density (oedema - grey)
b) Convex area of high density between the skull and the cortex
c) Concave area of low-medium density between the skull and the cortex
d) May have area of low density (oedema) in the territory of a major vessel