CT head - an approach (summary)

Dr Jeremy Jones and Dr Derek Smith et al.

CT head is a non-contrast CT and is performed for a variety of reasons. There are a number of ways to read and look at these scans, and these pages should give some help for what to look for.

There is a lot to take in, with scans including thousands of slices. In all cases, there are a few important things to review.

Reference article

This is a summary article; we do not have a more in-depth reference article.

Summary

  • be systematic
    • do the same thing every time you look at a CT
    • recognise normal
      • wide range depending on age of patient
  • initial review
    • who, what, why, where and when
      • what type of scan has been performed?
  • standard approach
    • symmetry
    • ventricles
    • parenchymal changes
    • grey-white differentiation
    • extra-axial spaces
    • bony defect
Standard approach

Start midline and assess symmetry - then work outwards.

  • symmetry
    • relatively easy to compare side-to-side
    • asymmetry is usually pathological
      • not all pathology gives rise to asymmetry
  • ventricles
    • ventricular enlargement may occur with ageing
    • hydrocephalus is enlargement secondary to increased pressure
      • often caused by obstruction downstream
  • parenchymal changes
    • change in density
      • hyperdense (bright): calcification or blood
      • hypodense (dark): ischaemia
    • masses
  • grey-white differentiation
    • the cortex and white-matter should be different shades
      • cortex appears brighter than white matter
      • if this is blurred, it is suggestive of ischaemia
  • extra-axial spaces
    • the brain should extend all the way to the bone
    • the spaces between the brain and skull is the extra-axial space
      • hyperdensity may represent acute blood
      • hypodensity may represent chronic blood or fluid
  • bony defect
    • abnormal bone texture
    • fractures
    • use bone algorithm to see fine detail
Medical student radiology curriculum
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Article information

rID: 32574
Section: Approach
Synonyms or Alternate Spellings:

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Cases and figures

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    Case 2: normal CT head
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    Case 3: acute subdural haemorrhage with significant mass effect
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    Case 4: chronic subdural haemorrhage with midline shift
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    Case 5: widespread subarachnoid blood
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    Case 6: acute ischaemic stroke
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    Case 7: encephalomalacia (chronic change following ischaemia)
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    Case 8: right temporal bone fracture in traumatic head injury
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