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Approach to CT Head Imaging

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Approach to CT Head Imaging

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Approach to CT Head Imaging

  1. 1. Approach to CT Head Dr Fan Zhang
  2. 2. Overview • Common indications • Basic anatomy • Emergency CT checklist • Trauma • Intracranial Haemorrhage • Stroke • Tumours • Cases
  3. 3. CT Head – Common Indications • Non-Contrast • Trauma • Stroke (± angiogram, perfusion) • Intracranial haemorrhage • Acute headache (eg. Thunderclap) • Hypoxia • Quick, easily accessible • Low dose (~2.3 mSv) • Post-Contrast Angiogram • Stroke/TIA workup (including CT perfusion) • Vascular workup (eg. Aneurysm, vascular malformation) • Post-Contrast • Neoplasms • Abscesses
  4. 4. CT Head anatomy • Grey matter • = Neurons • denser so overall higher density (37-42HU) • White matter • = Axons • have myelin (fatty), so overall lower density (20-30 HU) • Gyri & Sulci arranged in various lobes • CSF spaces – ventricles, basal cisterns • Misc – pituitary gland, pineal gland, choroid plexus • Intra-axial vs extra-axial
  5. 5. Emergency CT Checklist • Midline structures • Suprasellar region • Pineal region • Base of skull • Symmetry • Basal cisterns • Ventricles • 3rd & 4th ventricles in midline • Lateral ventricles not enlarged
  6. 6. Trauma • Blunt trauma >> penetrating trauma • Skull is much harder than brain; CSF acts as a cushion • Skull fracture – often subtle, can merge with cranial sutures • Subgaleal haematoma – indicates site of trauma • Coup / contre-coup injury pattern • Brain contusion – often inferior frontal lobe • Diffuse axonal injury
  7. 7. Intracranial blood • Patterns of intracranial bleeding: • Extra-axial • Epidural – blood between skull & dura • Subdural – blood between dura & pia mater • Blood along the falx is always SDH • Subarachnoid – blood between pia & arachnoid mater • Check the basal cisterns • Intra-axial • Intraventricular • Parenchyma – basal ganglia, lobar, grey/white matter junction • Lesional – eg. Neoplasm, haemorrhagic transformation of ischaemic infarct
  8. 8. Ischaemic Stroke • Key features: • Loss of grey/white matter differentiation • Insular ribbon sign • Dense vessel sign • Has to be appropriate & fit the clinical picture • CT angiogram – assess arteries • CT perfusion – assess salvageability
  9. 9. Tumours • Intra-axial vs Extra-axial • Primary vs Secondary • Primary • Glial series tumours / Glioblastoma • CNS lymphoma – hyperattenuating • Secondary • Metastases – multiple lesions
  10. 10. Cases…

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