The clot is on the right side of the brain. The labeling at the top of the image indicates "R" for right. It's important to always verify the left/right labeling when interpreting images to avoid potential mistakes from flipped or differently labeled images.

1. How to Read a Head CT
Dr: Muhammad Faisal. FCPS1(R4)
1

41. Sphenoid
sinus
Medulla
oblongata
cerebellum

42. 4 Fourth ventricle
5 Middle cerebellar
peduncle
6 Sigmoid sinus
7 Petrous temporal
bone and mastoid
air cells
8 Cerebellopontine
angle
9 Pons
10 Pituitary fossa

43. 11 Cerebellar
vermis
12 Basilar artery
13 Prepontine
cistern
14 Dorsum sellae
15 Temporal horn
of lateral
ventricle

44. 16 Ambient
cistern
17
Interpeduncular
cistern
18 Cerebral
peduncle
19 Sylvian
fissure

45. 20 Supra
vermian
cistern
21 Frontal
horn of
lateral
ventricle
21a Third
ventricle

46. 22 Head of
caudate
nucleus
23 Insular
cortex
24 External
capsule
25 Lentiform
nucleus
26 Thalamus

47. 27 Interhemispheric
fissure
28 Anterior limb of
internal capsule
29 Genu of internal
capsule
30 Posterior limb of
internal capsule
31 Trigone of lateral
ventricle and calcified
choroid plexus
32 Occipital horn of
lateral ventricle

51. CSF Production
• Produced in choroid plexus in the lateral
ventricles  Foramen of Monroe  IIIrd
Ventricle  Acqueduct of Sylvius  IVth
Ventricle  Lushka/Magendie
• 0.5-1 cc/min
• Adult CSF volume is approx. 150 cc’s.
• Adult CSF production is approx. 500-700
cc’s per day.
51

53. 53
2nd Key Level Sagittal View
2nd Key Level
Circummesencephalic
Cistern

54. Cisterns at Cerebral Peduncles Level
54

55. Right and left sylvian fissures (black arrows)
meeting at the suprasellar cistern.

57. A = Left
frontal horn
B = Left
sylvian fissure
C = Third
ventricle
D = Ambient
cistern

61. Head CT
“Blood Can Be Very Bad”
61

62. Blood Can Be Very Bad
• Blood
• Cisterns
• Brain
• Ventricles
• Bone
62

63. Blood Can Be Very Bad
• Blood
• Cisterns
• Brain
• Ventricles
• Bone
63

64. Blood Can Be Very Bad
• Blood
• Cisterns
• Brain
• Ventricles
• Bone
64

65. Blood Can Be Very Bad
• Blood
• Cisterns
• Brain
• Ventricles
• Bone
65

66. Blood Can Be Very Bad
• Blood
• Cisterns
• Brain
• Ventricles
• Bone
66

67. B is for Blood
• Blood becomes hypodense
at approximately 2 weeks.
67
•Blood becomes
isodense at
approximately 1 week.
• Acute blood is bright white
on CT (once it clots).

68. B is for Blood
• Blood becomes
hypodense at
approximately 2 weeks.
68
• Blood becomes
isodense at
approximately 1 week.
• Acute blood is bright white
on CT (once it clots).

69. B is for Blood
• Blood becomes
hypodense at
approximately 2 weeks.
69
• Blood becomes
isodense at
approximately 1 week.
• Acute blood is bright white
on CT (once it clots).

70. THE 5Ss OF ANY HAEMATOMA!
• Clots are defined by:
• Size
• Symptoms and signs
• Shifts
• Side
• site

72. Cerebral
contusions in
both frontal
lobes
(arrows). The
adjacent low
density
represents
local
oedema

73. Cerebral contusion
Characteristics
● Commonest form of traumatic intra-axial injury.
● Contusions occur at the inferior and polar surfaces
of the frontal and
temporal lobes.
● Injuries may be coup or contra-coup.
● Cerebral contusions are also produced secondary
to depressed skull fractures and are associated with
other intracranial injuries.

74. Clinical features
● Usually associated with a
brief loss of consciousness.
● Beware of the elderly
patients, alcoholics and patients
taking anticoagulants as they
are at increased risk of
haemorrhage.

76. Radiological features
● Non-contrast computed tomography (CT)
useful in the early posttraumatic period.
● Contusions are seen as multiple focal
areas of low or mixed attenuation
intermixed with tiny areas of increased
density representing petechial
haemorrhage.
● Magnetic resonance imaging (MRI) is the
best modality for demonstration of
oedema and contusion distribution.

77. Management
● Secure airway whilst the cervical spine is protected.
Supplemental oxygen.
Assess and stabilise breathing and circulation.
● If Glasgow coma scale (GCS) 8 discuss with
anaesthetist as a definitive (secured) airway is
required.
● Early discussion with radiologist and neurosurgeon.
● Titrate opioid analgesia.Cleanse and close scalp
injuries.Discuss with a neurosurgeon
regarding intravenous (i.v.) antibiotics, steroid and
mannitol use.

79. Lentiform-
shaped high
density left
extradural
haematoma
(arrows).
Note the
contra-coup
right temporal
contusions
(arrowheads).

81. Extradural haematoma
Characteristics EPIDURAL
● The majority of these are arterial (middle meningeal
artery) with a small proportion being of venous origin.
● Commonly unilateral and associated with a fracture in
adults. Skull fractures are often absent in children due to
skull elasticity.
● Haematoma forms between the inner table of skull and
the dura.
● May have associated injuries, such as a subdural
haematoma (SDH) or contusions.
● Arterial bleeding usually develops and presents rapidly
within 1 hour of injury whereas venous haematomas may
present after several days.

82. Clinical features
● Classically present following a head injury
with initial loss of consciousness
followed by a lucid interval, prior to a second
decrease in the level of
consciousness.
● Beware as only about 30% of patients present
in this way.
● The symptomatology depends on how quickly
the haematoma expands.
Progressive sleepiness, headache, nausea and
vomiting are suspicious

83. Radiological features
● CT signs include a biconvex hyperdense
elliptical collection with a sharply defined edge.
Mixed density suggests active bleeding.
● The haematoma does not cross suture lines.
● May separate the venous sinuses/falx from the
skull; this is the only type of haemorrhage to do
this.
● Mass effect depends on the size of the
haemorrhage and associated oedema.
● Venous bleeding is more variable in shape.
● Associated fracture line may be seen.

84. Management
● Airways, breathing,
circulation (ABCs).
● Definitive treatment involves
surgical evacuation; therefore
early discussion
with a neurosurgeon is
important.

85. 85

87. Multiple areas
of linear high
density are
seen within the
right cerebral
sulci
(arrows); these
represent
areas of acute
subarachnoid
haemorrhage

88. Subarachnoid Hemorrhage
88

89. Subarachnoid haemorrhage
Characteristics
● Spontaneous subarachnoid haemorrhage
(SAH) usually occurs secondary to a ruptured
aneurysm or arteriovenous malformation.
● Acquired aneurysms are commonest in the
circle ofWillis; at bifurcations with turbulent
flow.
● Commonest before 50 years of age, but may
occur at any age.
● Free blood causes irritation of the meninges.

90. Clinical features
● Acute severe headache often described as the worst
ever, although a mild headache does not exclude a
SAH.
● Vomiting, pallor and profuse sweating may occur.
● Neck stiffness and focal neurological signs seizures.
● coma.
● Complications include hydrocephalus (acute
obstructive and delayed communicating), cerebral
vasospasm leading to infarction and transtentorial
herniation secondary to raised ICP.
● Mimics many other conditions including
encephalitis, meningitis, acute
glaucoma and migraine amongst others

91. Radiological features
● Non-contrast CT is sensitive within 4–5
hours of onset.
● Look for acute haemorrhage (increased
density) in the cortical sulci, basal
cisterns, Sylvian fissures, superior
cerebellar cisterns and in the ventricles.
● MRI is relatively insensitive within the
first 48 hours but is useful after this
time and in recurrent bleeds to pick up
subtle haemosiderin deposition

92. Complications: The H.I.G.H
of SAH
HIGH stands for
Hydrocephalus,
Infarction,
Giant aneurysms
and Haematoma.

93. Management
● ABCs. Beware as patients may rapidly progress to
coma and require intubation.
● Supplemental oxygen, i.v. access and cardiac
monitoring are essential.
● Consider other causes for a decreased level of
consciousness.
● Check routine bloods and refer suspicious patients
for further investigation,
e.g. lumbar puncture or CT scan.
● A normal CT does not exclude a SAH.This group of
patients require a lumbar puncture.

95. (a) Acute SDH;
(b) Subacute SDH
(c) Chronic SDH

96. Subdural Hematoma
• Typically falx or sickle-
shaped.
• Crosses sutures, but does
not cross midline.
• Acute subdural is a marker
for severe head injury.
(Mortality approaches
80%)
• Chronic subdural usually
slow venous bleed and
well tolerated.
96

97. Subdural haematoma
Characteristics
● SDH commonly occurs in the elderly and in children
.
● Occur in the subdural space, i.e. the potential space
between pia arachnoid membrane and dura.
● Caused by traumatic tearing of bridging veins in the
subdural space.
● Often secondary to deceleration injuries, or direct
trauma in which there is movement of the brain in
relation to the skull. Beware forceful coughing/
sneezing or vomiting in the elderly.
● No consistent relationship to skull fractures.

98. Clinical features
● Often insidious due to the slow
build up of pressure.The resultant
mass effect over time can lead to
significant ischaemic damage.
● Clinical presentation depends on
the amount of trauma sustained and
the
speed of haematoma accumulation.

99. Radiological features
● CT shows a crescentic fluid collection between
the brain and inner skull.
Concave inner margin with minimal brain
substance displacement.
● Crosses suture lines but not dural reflections.
● In the acute phase the fluid collections appear
to be of high density; subacute phase (2–4
weeks post-injury) the collection is isodense to
brain
and in the chronic phase (4 weeks post-injury)
the collection is of low density.

100. Management
● ABCs.
● Discuss with neurosurgeon. Even small
haematomas may be suitable for
evacuation.
● Conservative management in patients
with haematomas only a few millimetres
thick may be appropriate after considered
discussion and further careful observation.

101. Intraventricular/
Intraparenchymal Hemorrhage

102. Schematic illustration showing the difference
between acute epidural haematoma (A) and acute
subdural haematoma (B). Can you confidently
distinguish the AEDH from the ASDH?

106. A and B. On which side of the brain is this clot? It is so easy to
inadvertently flip the CT films or the convention adopted may
be different from what you are used to; so ALWAYS CHECK
THE LABELLING OFLEFT AND RIGHT! See