Basic CT brain From Neurologist point of view

1. Basic 101 on CT
Neuroimaging
(from neurology point of view)
Dr Ahmad Shahir Mawardi
Neurology Department
Hospital Kuala Lumpur
25th May 2016

2. Content
• Basics of CT Neuroimaging
• Neuro anatomy on CT
• Common neurological conditions

3. Expectation(s)
• Able to
– do on-call confidently
– intreprete important CT findings

4. What not to expect(s)
• interprets CT scan like a 'pro'
• pass medical examination with flying colours

5. The Eyes Don't See
What the Mind Don't
Know

6. CT scan Intrepretation (Abnormal)
1. Lesion(s) (hyperdense/Hypodense)
2. Location
3. Age of lesion (acute/subcute/chronic)
4. + Cause, + complications
e.g
• Acute infact at the left internal capsule
• Acute communicating hydrocephalus

7. Pitfalls
• Pt name (make sure you have the right
pt!)
• Age
• Date
• CT (brain)
• Plane/View
• Plain vs contrast
• Findings

8. Part I
Basic of CT Neuroimaging

9. Basics of CT Neuroimaging
• Orientation
• Region/Planes
• Windows
• Density
• Slice thickness
• Contrast enhancement

10. Basics of CT Neuroimaging: Orientation

11. Basics of CT Neuroimaging: Orientation

12. Basics of CT Neuroimaging:
SYMMETRY
MIRROR IMAGE
CT brain – 2 identical half

13. Basics of CT Neuroimaging: Planes

14. Basics of CT Neuroimaging: Planes
A
S
C

15. Basics of CT Neuroimaging: Window

16. Basics of CT Neuroimaging: Density
• Hypodense
• Hyperdense
• Isodense

18. Basics of CT Neuroimaging: Density

19. HYPERDENSITIES
Most common:
•Blood
•Calcification
•Exception to
the rule:
– Pineal gland
– Choroid plexus
Left temporal
epidural haematoma

20. HYPODENSITY
Most common:
•Infarction
•Fluid
– edema, infection,
tumour
•Hydrocephalus
•Air

21. Basics of CT Neuroimaging: Density
The Density of Blood Changes with Time!

22. Basics of CT Neuroimaging: slice thickness
• Scanogram
– Plane used for
scanning
– Anatomic extent of
series of scans
• Slice thickness may vary
(5-10 mm)

23. CT brain: Contract vs non-contrast
• Contrast:
– Vascular lesion
– Tumor
– Sites of infection
• CTA (stenosis)
• CTV (CVT)
• Leptomenigeal
enhancement
(meningitis)
• Ring enhancing lesion

24. Ring enhancing lesion
• Tumour
– Primary (GBM, lymphoma)
– Metastasis
• Infections:
– Abscess
– HIV associated:
toxoplasma, crytococcus
– TB/ tuberculoma
– Neurocysticercosis
• Resolving hematoma (10-21
days)
• Radiation necrosis
• Postoperative change
• Aneurysm
• Multiple sclerosis/ADEM (MRI)

25. Ring enhancing
lesion

26. Part II
NeuroAnatomy

28. Identification of structures

29. Lateral View of Brain

30. Ventricular System

31. Cross-sectional Anatomy
• Grey/White interface, Subcortical white matter

32. Cross-sectional Anatomy
• Paired of crescent-shape = Twin bananas

33. Cross-sectional Anatomy

34. Basal ganglia

35. Cross-sectional Anatomy
• Third ventricle, Basal ganglia, Superior cerebellar cistern

36. Physiologic Calcification

37. Brain Anatomy

38. Cross-sectional Anatomy
• Third ventricle, Smiley face

39. Cross-sectional Anatomy
• Midbrain, Interpeduncular cistern

40. Cross-sectional Anatomy
• Star shape ~ Circle of Willis,
• Fourth ventricle, Temporal horn ~ slit

41. Cross-sectional Anatomy
• Base of skull, Midline bony prominence,
• Prepontine cistern, Pretrous bone, Frontal sinus

42. Cross-sectional Anatomy
• Orbits, Ethmoid air cell

43. Part III
Common neuropathological findings

44. Common neuropathological findings
• Stroke
• Haemorrhage
• Hydrocephalus
• Leptomeningeal enhancement
• CNS infections

45. Ischemic stroke
• Location:
– Cortical infarction
– Lacunar infarction
– Watershed / Borderzone infarction
• Timing:
– Hyperacute changes
– Early changes
– Established changes
• Complications:
– Haemorrhagic transformation
– Cerebral oedema

46. Cortical signs
• Aphasia
• Neglect (may be spatial, sensory, visual, auditory)
• Alteration of consciousness
• Visual field cut

47. Stroke: Cortical Infarction
• Follows vascular territory
– ACA
– MCA
– PCA
– Mixed
• Wedge shape
• May have complications
– Haemorrhagic
transformation
– Cerebral oedema
• Usually embolic aetiology

52. Lacunar Infarction
• Sites (BITCP)
– Basal Ganglia (Caudate, Putamen)
– Internal capsule
– Thalamus
– Pons
– Cerebellum
• 3-15 mm in diameter
• Distal distribution of penetrating arteries
– Lenticulostriate
– Thalamoperforators
– Pontine perforators
– Recurrent artery of Heubner
• Fibrinoid degeneration

53. Penetrating arteries/
perforators
Lacunar Infarction

54. Lacunar Infarction

55. Borderzone Infarction
• Cortical Borderzone
• Internal Borderzone
• Pathology / Occlusion of
proximal vessels – ICA

56. Hyperacute changes
• Dense MCA sign
• Dot sign
• Loss of gray-white
differentiation
• Loss of sulcation
• NORMAL
• As early as 2-6 hours
from onset

57. 6 hours 24 hours 40 hours

59. ASPECTS score

60. What ASPECTS tell us
• Functional Outcome
• Risk of bleeding

61. Intracerebral
Haemorhage
• Typical hypertensive sites:
– Lenticulostriate vessels
• Basal Ganglia (Caudate, Putamen)
• Internal capsule
• Thalamus (a/w intravent. Ext)
• Pons
• Cerebellum
– Complications:
• Mass effect
• Obstructive hydrocephalus

62. Intracerebral
Haemorrhage
• Atypical sites!!!:
– Cerebral Amyloid Angiopathy
• 15% of ICH in pts > 60 yrs old
– AVMs
• Intracerebral haemorrhage or SAH
• Ix: CTA

63. Venous Infarction
• Thrombosis of cerebral veins
– Evidence of thrombosis – Dense cord sign,
Delta / Empty delta sign
– Complications of CVT – SAH, Atypical infarcts.
Haemorrhage

64. Haemorrhage

67. Epidural Haematoma
• Biconvex
• restricted by dural tethering at
the cranial sutures
Subdural Haematoma
• Crescent-shaped
• They do not cross the midline
because of the meningeal
reflections

68. Subarachnoid haemorrhage

69. Subarachnoid haemorrhage

70. Hydrocephalus
Ventriculomegaly a/w raised ICP
•Communicating/Non-obstructive:
– Impaired reabsorption of CSF fulid in the absence of any CSF flow
obstruction
•Non-Communicating/Obstructive:
– CSF-flow obstruction
• Foramen of Monro
• Aqueduct of Sylvius
• Fourth Ventricle obstruction

71. Hydrocephalus
• Acute
- “Ballooned” ventricles with
periventricular low density “
halo”
- 3rd
ventricle - rounded
• Chronic
– “Ballooned” ventricles
without periventricular halo
- 3rd
ventricle – normal app
• Obstructive:
– Basal cisterns, sulci compressed /
obliterated

72. Hydrocephalus Hydrocephalus ex-vacuo

73. Tuberculous Meningitis
1.Meningeal enhancement:
2. Infarction (20.5 – 30.8%):
- thalamus, basal ganglia, internal capsule
3. Hydrocephalus
4. Tuberculomas
-Infrequently seen except in miliary TB
5. Vascular changes
-uniform narrowing of large segments
-small segmental narrowing
-irregular beaded appearance
-complete occlusion.
Postgrad Med J 1999;75:133 140 doi:10.1136/pgmj.75.881.133

74. TB Meningitis: Tuberculomas
Contrast-enhanced CT
•showing multiple
tuberculomas in a patient
with tuberculous meningitis
Postgrad Med J 1999;75:133 140 doi:10.1136/pgmj.75.881.133

75. Meningioma

76. Right Temporal Glioblastoma

77. High grade glioma –
usually Glioblastoma

78. Brain Abscess

79. Herpes Encephalitis
• Predilection for limbic system:
– Temporal lobes
– Insular cortex
– sub frontal area
– cingulate gyri.
• Initially unilateral --> "sequential
bilaterality" is highly suggestive of
HSE1.

80. Toxoplasmosis Primary CNS Lymphoma

81. Thank You

82. Hydrocephalous

83. Subarachnoid hemorrhage