Presentation by Mr Arshad 27 July 2011>
CT Scan speaks the language of DENSITY
the brighter or whiter - more dense
why gray matter is more dense compared with the white matter
- gray matter composed of cell bodies, more dense because of the vascularity (blood supply)
- white matter composed of neurones, less dense, looks grey
3 normal calcification in the CT brain
1. bilateral choroid plexus
2. pineal region
they made a pyramid
sometimes the calcification can be seen in area of basal ganglia or thalamus
Mass effect & Midline shift
If there is tumour or lesion compressing the brain, there'll be mass effect
- sulci effaced
- sylvian fissure effaced etc
how to know the midline shift
- measure from septum pellucidum
A scan can have mass effect without midline shift
but cannot have midline shift without mass effect
CT brain with contrast
how to know?
the contrast will be in the veins, arteries and slyvian fissure
Extradural Haemorrhage
Why EDH has lens shape (convex)
- because there is no subdural space for the blood to go, so it expands
- stripping of dura
- associated with fracture
Why EDH not hyperdense
1. patient is anaemic
2. fresh blood, blood still not coagulate
3. patient has coagulopathy, blood didn't clot
Subdural Haemorrhage
Why concave shape
- blood collected along the space
Acute SDH
- within 2 weeks of haemorrhage
- blood still clot
Subacute SDH
- after 2 weeks of haemorrhage
- blood started to liqufied
Subdural haemorrhage usually causing midline shift and produce oedema
Chronic SDH
Vascular layer of the brain situated within subarachnoid space (between pia and arachnoid)
Haemorrhage due to aneurysm usually in basal cistern (weak blood vessel)
Subarachnoid haemorrhage
-usually traumatic
-at sulci
blood in CSF
-can be also in the ventricle
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