Head CT Basics : Trauma

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Head CT Basics Trauma

• Micelle Haydel, MD
• LSU-New Orleans

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First, a little test
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Head CT Interpretationthe basics
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A Little History...

• In the early 1970s, Hounsfield developed a way of
  computerizing Xrays to select certain densities
  for viewing.
• Plain films black, white or a few shades of
  grey
• CT thousands of shades of grey based on the
  density of the tissue (Hounsfield Units)

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What We Need to Know

• Air is very black (less than -300 HU)
• Water/CSF is black (near 0 HU)
• Bone is very dense/white (500-3000 HU)
• Blood is white (60-80 HU)
• Brain is gray 35-50 HU

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Before we look at abnormal, A little normal
geography

• Use the Cisterns Ventricles as landmarks

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4th Ventricle
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Suprasellar Cistern
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Sella turcica Suprasellar
Suprasellar Cistern
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3rd Ventricle Quadrigeminal Cistern
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Temporal Horn of Lateral Ventricle
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3rd Ventricle Quadrigeminal Cistern
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Lateral Ventricles
Frontal Occipital
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Lateral Ventricles
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Review
Temp Horn
Suprasellar
3rd
Quad
4th
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Normal Head
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ABNORMAL CTs
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• On each brain slice look for
• Symmetry, symmetry, symmetry
• sulci
• cisterns and ventricles
• grey-white differentiation

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• Identify What Doesnt Belong
• Hyperdensities (whiter)
• extra-axial hematomas (SDH, EDH)
• ICB or contusion
• SAH in sulci, cisterns or ventricles
• Hypodensities (darker)
• pneumocephaly (air is darker than CSF)
• infarction

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• Identify What Doesnt Belong
• Localized or diffuse edema
• effacement of sulci or cisterns
• distortion of gray-white matter interface
• enlarged ventricles, temporal horn
• Fractures
• soft tissue swelling
• fluid (blood) in sinuses or mastoid air cells
• in children, look for widened sutures
• Always look at bone windows

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Blood Acute blood is white (60-80 HU) on CT, due
to the density of hemoglobin. As hgb breaks
down, the HU decrease (i.e. subacute and isodense
hematomas)
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Dura tightly adhered to skull, but loosely to
brain.
Dura mater
Pia mater
Arachnoid
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• Epidural Hematoma
• Lens shaped (dura tightly adhered to skull
• Can cross midline
• Frequently assoc. with fracture

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Small Epidural Hematoma
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Very Small Epidural Hematoma
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Epidural with fracture
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Very Small Epidural Hematoma with fracture
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Epidural with Pneumocephaly
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Subdural Hematoma Follows the contour of the
brain doesnt cross the midline
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Small SDH tracking down midline
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Small Subdural Hematoma
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Very Small Subdural Hematoma
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Large Subdural Hematoma with shift
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Isodense Subdural Hematoma
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Hygroma with shift s/p SDH
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Acute on Chronic Subdural Hematoma
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Intraparenchymal Bleed
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Intraparenchymal Bleed Skull Fracture
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Intraparenchymal Bleed Contusions
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Contusion
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Pneumocephaly and contusion
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Subarachnoid hemorrhage- Blood in the 4th
Ventricle
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Subarachnoid blood in the suprasellar cistern
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Subarachnoid blood tracking along the sulci
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Intra-Ventricular Blood throughout
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Temporal Horn enlargement
Subdural hematoma
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Epidural
Enlarged Temporal Horn
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Diffuse Edema, SAH tracking across tentorium
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Subfalcean herniation (midline shift) due to SDH
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Uncal herniation (EDH subfalcean herniation)
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Diffuse Edema s/p SAH
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Soft-tissue swelling
Fracture
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.the results
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Epidural Hematoma
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Skull Fracture SAH
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Cerebral Contusion
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SAH
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Subdural Hematoma Subfalcean Herniation
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Epidural Hematoma
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Diffuse Edema
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Isodense Subdural
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Subdural Hematoma
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