2. BRAIN CT SCAN
PART I
REVIEW FOR ANATOMY AND
Common acute conditions
for clinician
3. SCHEME OF THE LECTURE
BASIC PRINCIPLES OF CT SCAN
NORMAL ANATOMY AS SEEN ON
CRANIUM CT SCANS
ILLUSTRATIONS
4. Basics :
• X-RAYS ARE ABSORBED DIFFERENTLY BY DIFFERENT
TISSUES
• Always describe CT findings as densities-
isodense/hypodense/hyperdense.
• Higher density = the appearance IS WHITER
• Lower density = the appearance IS DARKER
• Brain is the reference density
• Anything of the density as brain= isodense
• Higher density than brain= hyperdense ( BONE is
example)
• Anything darker than brain= hypodense( ie. CSF and air )
5. HOUNSFIELD UNITS
H.U ? !
Represent the density of tissue
Calculated automatically by Ct scan machine
processor by Place the marker on area of
interest
27. I schaemic Stroke
1 st 6 Hours :
60% Normal
Vogue subtle Hypodensity .
Sulcal effacment
Loss of Grey/White matter Distinction ...
12-24 More prominant low attenuated
area .
28. Ischaemic Stroke
After 24 hours
Well demarcated low attenuation .
3-5 days
Mass effect which may gone by 2-4 weeks .
LongTerm
Encephalomalcia
33. Sub Dural and Epidural Hematoma
Usually traumatic >>>
Subdural
Venous bleed
due to stretching and tearing of bridging
cortica
34. Epidural
Arterial bleed
The source of bleeding is usually a torn
meningeal artery (most commonly, the
middle meningeal artery)
meningeal artery.
Skull Fracture .
>95% are supratentorial
temporoparietal: 60%