This document discusses the radiological anatomy of the brain as seen on CT scans. It begins by outlining the systematic approach used to interpret CT scans, including assessing symmetry, midline structures, cross-sectional anatomy, and skull and soft tissues. It then describes key anatomical structures visible on CT such as the cranial fossae, meninges, fissures, ventricles, grey and white matter. The document also discusses how CT is used to identify ischemic strokes at different stages, from immediate changes like hyperdense vessels, to acute swelling, subacute resolving swelling, and chronic infarction. It notes CT perfusion can identify the infarct core and penumbra using parameters like CBV, CBF, MTT and

1. RADIOLOGICALANATOMY OF
BRAIN IN CT SCAN
Akshai George Paul

2. Systemic Approach to head CT
 Symmetry
 Midline
 Cross-sectional anatomy
o Brain tissue
o CSF space
o Skull and soft tissues
 Subdural space
 Bone windows

3. Cranial Fossae

4. Meninges

6. Fissures

7. Ventricles

8. Brain Parenchyma

9. Grey matter structures

11. White matter structures

12. Normal CT of Brain
• Sulci are symmetrical on both
sides
• Midline is straight
• Grey-white distinction is clear
• Ventricles are normal sized
• Skull is intact with no scalp
edema.

13. Above the level of Foramen Magnum

14. At the level of FourthVentricle

15. Above the level of fourth ventricle

16. At the level of theThirdVentricle

18. Above theVentricular level

19. Above the ventricular level

21. Physiological Calcification

22. VASCULAR
TERRITORIES

27. CT IN ISCHEMIC STROKE

28. Ischemic stroke can be further classified on the basis of the time from the onset of
symptoms as
■ hyperacute
■ acute
■ subacute
■ chronic

29. the goals of CT in an acute setting are:
1. exclude ICH
2. look for early features of ischemia
3. exclude other IC pathologies that may mimic the stroke

30. Immediate change
• The earliest CT sign visible is the
hyperdense segment of a vessel,
representing the intravascular thrombus
or emboli.
• Its most often observed in the MCA:
MCA Dot sign/ hyperdense MCA sign

31. Acute stroke
• Loss of grey-white matter
differentiation .
• Cortical hypodensity with associated
parenchymal swelling with resultant
gyral effacement
• Insular ribbon sign
• There will be significant mass effects
also due to the swelling

32. Subacute stroke
• The swelling starts to subside and small
amounts of cortical petechial
hemorrhages may appear.
• This is known as CT fogging
phenomenon.
• Can be misleading as the affected
cortex may appear normal.

33. Chronic infarct
• Here the residual swelling passes and
gliosis sets in.
• Finally it appears as a region of low
density with negative mass effect.
• Sometimes, cortical mineralisation can
be seen as hyperdense areas.

34. CT perfusion
■ Allows to identify both the core of infarct and the penumbra.
■ The following parameters are used for its identification:
 Cerebral blood volume(CBV)
 Cerebral blood flow(CBF)
 Mean transit time(MTT)
 Time to peak (TTP)