INTRODUCTION TO CT HEAD FOR THE ADVANCED … CT... · 2019-03-09 · Herpes Encephalitis • HSV...
Transcript of INTRODUCTION TO CT HEAD FOR THE ADVANCED … CT... · 2019-03-09 · Herpes Encephalitis • HSV...
INTRODUCTION TO CT HEAD
FOR THE ADVANCED
PRACTICE PROVIDER
Ervin Lowther, MDMedical Director of Neuroradiology
Prisma Health - Upstate
Obligatory Picture #1
Obligatory Picture #2
Can’t miss 4 H’s on a head CT
• ?
• ?
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• ?
Name 3 CT Signs of Early Infarction
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4 Types Intracranial Hemorrhage
Outline
• CT concepts
– Density
• Concepts in brain imaging
– Gray-white differentiation
– Types of cerebral edema
– Sulci
CT
FDA Website, 6/28/13
Sir Walter Hounsfield
1972
CT Attenuation
– Density of tissue Gray scale
• air black
• fat darker gray
• CSF gray
• brain lighter gray
• acute blood, contrast white
• bone very white
CT HU In The Brain
• HU of grey matter (GM) and (WM)
– GM ~ 40
– WM ~ 30
• HU of hemorrhage
– Hyperacute ~ Hct
– Acute ~60-80
– Subacute ~ 40
– Chronic ~ 0-20
Relevant CT Anatomy
Important CT concepts in
Brain Imaging
• Attenuation
• Gray-white differentiation• Types of cerebral edema
– Determine stroke versus stroke mimic
• Sulci
Grey-White Differentiation
Types of Cerebral Edema
Cytotoxic• Brain cells die
• Influx of water into GM
• Lose GM-WM
differentiation
Vasogenic• Something irritates the
brain
• Influx of water in WM
• Accentuates GM-WM
differentiation
GM is the key!
Types of Cerebral Edema
Cytotoxic Vasogenic
WM Edema
Edema
WM
GM WM
WM
Edema
WM
Causes of Cerebral Edema
Cytotoxic
• Anything that causes the
cells to die
• Infarcts/Ischemia
• Necrotizing infection
Vasogenic
• Anything that disrupts the
blood brain barrier
• Neoplasm
• Infection
• Tumefactive demyelination
Stroke
• Death of brain cells due to lack of oxygen– Caused by blockage of blood flow or rupture of a blood
vessel
• Stroke is a clinical diagnosis
• We see infarcts on imaging
CT Signs of Infarction
• 3 early signs of infarction
– Loss of grey-white matter differentiation
• Loss of insular ribbon
– Sulcal effacement
– Hyperdense vessel sign
Baseline CT < 3 hrs
Case
Day 3 CT s/p t-PA
Case
Identify Vascular Territory
• Must identify vascular distribution
– Middle cerebral artery (MCA)
– Posterior cerebral artery (PCA)
– Anterior cerebral artery (ACA)
– Basilar artery (BA)
– Cerebellar arteries
• Superior cerebellar artery (SCA)
• Anterior inferior cerebellar artery (AICA)
• Posterior inferior cerebellar artery (PICA)
Vascular Territories
http://rad.desk.nl/en/p484b8328cb6b2
Bilateral ACA Infarcts And Cerebral
Edema
Day 3 CT s/p TPA
MCA infarct with hemorrhage
diffuse anoxic injury
How ‘bout this one?
Can’t Miss 4 H’s
• Hemorrhage
• Hydrocephalus
• Herpes
• Herniation
Intracranial Hemorrhage
• Intraparenchymal
• Subarachnoid
• Subdural
• Epidural
• Intraventricular
Hypertensive Hemorrhage
• Most common sites– Basal ganglia
• Most common site
– Thalamus
– Brainstem (pons)
– Cerebellum
HTN Bleed
Subarachnoid Hemorrhage
• Within the subarachnoid spaces
– Cisterns
– Fissures
– Sulci
• Most common cause of SAH?
– Trauma
Acute SAH
Subdural Hemorrhage
• Between the dura and arachnoid
• Crescentic
• Can cross suture lines– Cannot cross the midline
• Superior sagittal sinus
• Not necessarily associated with a frx– But you’d better still look
Subdural Hemorrhage
What about this one?
Epidural Hemorrhage
• Between the skull and dura
• Lenticular
• Does not cross the sutures– Dura is tightly adherent at sutures
• Highly associated with a fracture
HEMORRHAGE
IPH SAH SDH EDH
Gratuitous Picture
Which One of the 4 H’s?
Hydrocephalus
• Enlargement of the ventricles due to
alteration of CSF flow
• Communicating or non-communicating
(obstructive)
• Look for enlargement of the temporal horns
and rounding of the third ventricle!
Hydrocephalus on MRI
Gratuitous Picture
Infarct or One of the 4 H’s?
Vascular Territories
http://rad.desk.nl/en/p484b8328cb6b2
Infarct or One of the 4 H’s?
Infarct or One of the 4 H’s?
Herpes encephalitis
Herpes Encephalitis
• HSV causes necrotizing encephalitis
– Usu HSV-1
• Limbic system
– Temporal lobes, insula, hippocampus,
subfrontal area, cingulate gyrus
• Can be symmetric or asymmetric
• Can be hemorrhagic
– Necrotizing hemorrhagic encephalitis
Herniation
• Many different types but most commonly
– Uncal
– Subfalcine
– Tonsillar
– Transtentorial
1. Inferior displacement of
sylvian fissure
2. Subfalcine herniation
3. Entrapment of lateral ventricle
4. Compression of ACA
5. Midbrain contusion
6. Duret (midbrain) hemorrhage
7. Descending transtentorial
herniation
8. Compression of PCA
9. Widening of ipsilateral CPA
10. Descending tonsillar
herniation
CEREBRAL HERNIATIONS
Uncal Herniation Subfalcine Herniation
Wrap It Up!
HEMORRHAGE
IPH SAH SDH EDH
Can’t Miss 4 H’s
• Hemorrhage
• Hydrocephalus
• Herpes
• Herniation
Name 3 CT Signs of Early Infarction
• Loss of gray-white differentiation
• Sulcal effacement
• Hyperdense vessel sign
Take Home Points
• Stroke remains a clinical diagnosis
• Best initial test = noncontrast head CT
• GM is the key to differentiating types of edema
Take Home Points
• Look at insular ribbon for early MCA
infarcts
• Look at temporal horns for early hydro
• Check the interpeduncular fossa for SAH