Swirl sign (intracranial hemorrhage)

The swirl sign refers to the non-contrast CT appearance of acute extravasation of blood into a hematoma, for example an extradural hematoma or subdural hematoma. It represents unclotted fresh blood which is of lower attenuation than the clotted blood which surrounds it 1.

It is the corollary of the spot sign on CTA which represents the same phenomenon, but in that case caused by contrast extravasation 2.

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Article information

rID: 6594
Section: Signs
Synonyms or Alternate Spellings:
  • Swirl appearance in intracranial haemorrhage

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Cases and figures

  • Case 1: extradural hematoma
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  • Case 2: extradural hematoma
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  • Case 3: subdural hematoma
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