Signal flare phenomenon

The signal flare phenomenon is a useful sign to identify active bleeding in a liquefied haematoma with haematocrit effect on dynamic CT scan images.

When active arterial haemorrhage is present in a liquefied haematoma that has a haematocrit effect, a signal flare phenomenon may be seen as a linear, high attenuating focus in the dependent layer as well as very high-attenuation foci at the boundary of the two fluid-fluid levels. 

This is due to movement of very-high attenuation extravasated contrast material through the dependent cellular layer to the boundary of the cellular and liquid layers, based on differences in specific gravity.

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Article information

rID: 21491
System: Vascular
Section: Signs
Synonyms or Alternate Spellings:
  • Signal flare phenomena

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