Transcript CT Brain IN EMERGENCY BOQAI

‫بسم هللا الرحمن الرحيم‬
BRAIN CT
IN EMERGENCY
Lecture Objectives:
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Normal anatomy of brain CT
Trumatic brain injury
Subarachnoid hemorrhage
Intraparenchymal hemorrhage
Stroke
Brain edema
Cerebral herniation
NON- ENHANCED CT STUDY
CONTRAST ENHANCED CT STUDY
A. Orbit
B. Sphenoid Sinus
C. Temporal Lobe
D.Externa Auditory Canal
E. Mastoid Air Cells
F. Cerebellar Hemisphere
A. Anterior Horn of the Lateral
Ventricle
B. Caudate Nucleus
C. Anterior Limb of the Internal
Capsule
D. Putamen and Globus Pallidus
E. Posterior Limb of the Internal
Capsule
F. Third Ventricle
G. Quadrigeminal Plate Cistern
H. Cerebellar Vermis
I. Occipital Lobe
A. Falx Cerebri
B. Frontal Lobe
C. Body of the Lateral Ventricle
D. Splenium of the Corpus Callosum
E. Parietal Lobe
F. Occipital Lobe
G. Superior Sagittal Sinus
A. Falx Cerebri
B. Sulcus
C. Gyrus
D. Superior Sagittal Sinus
CT SCAN..
Bone window
fracture
BRAIN MRI STUDY
T1WI
FLAIR
T2WI
CT SCAN..
Contrast enhanced CT:
IV injection of contrast medium
is often given because the
abnormality not seen in pre
contrast scans may be
rendered visible following
contrast enhancement
(consequence of breakdown of
blood brain barrier allowing
contrast to enter the lesion
particularly in neoplasm,
infection, inflammation and
certain stage of ischemia).
Also it is helpful in
demonstrating blood vessels
MCA
ACA
Basilar
artery
Straight sinus
Superior
sagittal sinus
Contrast enhanced CT
CT SCAN..
Computer reconstructions
can in selected circumstances
be made from the axial
sections
which
then
provide images in coronal
or sagittal planes.
Sagittal reconstruction
Coronal reconstruction
CT SCAN..
CTA
CT angiography is helpful in
diagnosis of vascular
diseases and abnormalities
such as stenosis, occlusion
or vascular malformation
Occlusion of left middle cerebral artery
Computed Tomographic Cerebral
Venography (CTV)
CTV
Can be reliably assess intracranial venous
system
Comparable to MR angiographic
techniques
Rapid and readily available
Avoids many patient contraindications
that may prevent MR evaluation
Using iodinated contrast material, requires
complex post processing to remove
bony structures from reconstructed
images
CT SCAN..
CT PERFUSION
cerebral blood volume
cerebral blood flow
CT SCAN..
CT PERFUSION
In acute stroke, very early cranial CT may be normal. Perfusion
CT shows great promise in refining the selection of patients
suitable for thrombolysis, as it can accurately determine infarct
core from potentially salvageable ischaemic penumbra.
Some cerebral tumours are associated with angiogenesis
and a breakdown of the blood-brain barrier. Angiogenesis
can be detected as an increase in flow and volume
parameters, and blood-brain barrier breakdown can be
quantified as contrast accumulates in the interstitial space.
Such aggressive features can distinguish malignant from
benign tumours when standard imaging may not.
Traumatic brain injury:
• Primary:
• Extraaxial hemorrhage:
- Epidural hematoma
- Subdural hematoma
- Subarachnoid hemorrhage
• Intraaxial lesions:
- Diffuse axonal injury
- Cortical contusion
- Deep gray matter injury
- Brainstem injury
- IVH
• Secondary:
- Brain herniation
- Traumatic ischemia
- Diffuse cerebral edema
- Hypoxic brain injury
Epidural hematoma
• 90% is arterial (middle meningeal
artery)
• Temporoparietal
• Biconvex, lenticular
• Does not cross suture lines, crosses
dural reflections
• Commonly associated with skull
fractures
CT SCAN..
Bone window
Brain window
fracture
Acute extradural hemorrhage
The window settings are selected for
the brain, but may be altered to shows
the bones.
Subdural hematoma
• Tear of cortical bridging veins
• Cresentric along the brain surface
• Crosses suture lines, does not
cross dural reflections
• Common in infants (child abuse)
and in the elderly
Subarachnoid hemorrhage
• Hyperdense CSF in the basal cisterns,
sylvian fissure and subarachnoid
space
• Aneurysm rupture is the most common
cause in non trauma patient
• Patients present with the worst
headache of their life
Subarachnoid hemorrhage
Subarachnoid hemorrhage
• The pattern of hemorrhage may give a
clue to the location of the ruptured
aneurysm:
• A-com aneurysm ⇒ interhemispheric fissure
• P-com aneurysm ⇒ ipsilateral basal cisterns
• MCA trifurcation ⇒ sylvian fissure
• Basilar tip ⇒ interpeduncular cistern,
intraventricular
• PICA ⇒ posterior fossa cisterns, intraventricular
Pseudo-subarachnoid
hemorrhage
• Symmetric increased density in the
basal cisterns with no sulcal density
• 30-40 HU
• Assoaciated with generalized brain
edema
• History of recent cardiopulmonary
resuscitation
Diffuse axonal injury
• Axonal disruption from shearing forces of
acceleration/deceleration
• Patients are unconscious with severe
head injury
• Common locations:
- Lobar gray/white matter junction
- Corpus callosum
- Dorsolateral brain stem
Diffuse axonal injury
• Initial CT is often normal. Petechial
hemorrhage develops later.
• Susceptibility-sensitive, gradient-echo
MR sequences are most sensitive for
detecting hemorrhagic shear injuries.
Diffuse axonal injury
Cortical contusions
• Focal hemorrhage/edema secondary to
brain impacting on bone or dura
• Located 180 degrees from the site of direct
impact (contrecoup)
• Characteristic locations:
- Anterior temporal
- Inferior frontal
- Parasagittal hemisphere
- Splenium of the corpus callosum
- Brainstem
Intra ventricular hemorrhage
Intraparenchymal hemorrhage
• Causes:
- Hypertension
- Amyloid angiopathy
- Vascular malformations
- Coagulopathy
- Trauma
- Drug induced
- Tumor hemorrhage
Stroke
• Types:
- Ischemic stroke
- Hemorrhagic stroke
- Venous occlusion
Ischemic stroke
• Nonenhanced CT is the initial investigation
of choice
• Exclude hemorrhage and underlying mass
or AVM
Imaging findings:
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Normal in early stroke
Hyperdense clot in the affected artery
Insular ribbon sign
Sulcal effacement
Cytotoxic edema develops by 6 hours
Ischemic stroke
• Acute infarction cannot be excluded
on the basis of a negative CT.
• Diffusion weighted MRI is most
sensitive for detecting acute infarction
• Hemorrhagic transformation can
develop in the subacute stage
(gradient echo MRI)
Insular Ribbon Sign
1st Day
2nd Day
Old CT
Recent CT
PICA Infarction
Dense basilar artery (arrow). Compare this to
the normal internal carotid artery (arrowhead).
Cerebral Venous Thrombosis
• Can involve the: dural sinuses,
cortical veins or deep cerebral
veins
Venous occlusion
Spectrum of CT findings
• 10-30% of cases of CVT are negative on either unenhanced or
contrast-enhanced CT
• Highly suspicious cases should be furtherly evaluated with CT
venography or MRI
• Unenhanced CT:
Direct signs of CVT “dense clot sign”
seen only on 30% of cases.
Diffuse brain edema 20-50%
• Unenhanced CT:
Venous infarction:
• Not conforming to a major arterial vascular territory,
• Involving subcortical region
• solitary or multiple isolated lesions
• Hemorrhagic or non hemorrhagic.
• Unenhanced CT:
Bilateral infarction at thalami,
basal ganglia and internal
capsules suggesting deep
venous thrombosis
• Contrast-Enenhanced CT:
Direct evidence of CVT “Empty Delta Sign”
Indirect evidence of CVT may be seen as
contrast enhancement of the adjacent dura
or vascular engorgement
CT Venography:
Allow direct visualization of
thrombus as filling defect
1st day
2nd day
Diagnostic Pitfalls
Pseudodelta sign
Normal variant of dense sinus
Unenhanced CT scans show subdural hemorrhage along falx and tentorium
cerebelli, simulating sagittal and transverse sinus thrombosis.
Brain edema
• Cytotoxic:
- Due to cellular swelling
- In the setting of cerebral ischemia
- Involves both gray and white matter
• Vasogenic:
- Disruption of BBB and leakage of fluid
outside capillaries
- Associated with tumors and abscesses
- Involves only the white matter
Brain edema
Cytotoxic
Vasogenic
Diffuse brain edema
• Causes include: ischemia and severe
head injury
• High morbidity and mortality
• Effacement of the cortical sulci and
basal cisterns
• Loss of gray/white matter interface
• White cerebellum sign
Cerebral herniation
• Mechanical displacement of the brain
secondary to mass effect
• Causes neurologic dysfunction and
vascular compromise
• Types:
- Subfalcine
- Transtentorial (descending, ascending)
- Tonsillar
Cerebral herniation
• Subfalcine herniation:
- The cingulate gyrus slips under the falx
cerebri
- Compression of the ipsilateral ventricle
and enlargement of the contralateral
ventricle
- ACA ischemia
Cerebral herniation
• Descending transtentorial herniation (uncal):
- The medial temporal lobe displaces through the
tentorial notch
- Presents clinically with deteriorating level of
consciousness, ipsilateral 3rd nerve palsy and
contralateral motor deficit
- Effacement of the ipsilateral suprasellar cistern
and enlargement of the ipsilateral CPA cistern
- The midbrain impacts the contralateral tentorium
(Kernohan’s phenomenon, Duret hemorrhage)
- PCA ischemia
Cerebral herniation