Island sign

Last revised by Joshua Yap on 9 Sep 2022

The island sign is a radiological sign seen on non-contrast CT of the brain. It is used as a marker to predict haematoma expansion and prognosis in patients with intracerebral haemorrhage 1. It is posited that the small islands of haematomas represent multiple sources of haemorrhage from injury to adjacent arterioles. 

The island sign is defined as either 2:

  • ≥3 small discrete haematomas that are not connected to the primary haematoma; or
  • ≥4 small haematomas that may branch off from the primary haematoma and resemble "bubbles" or "sprouts" rather than a lobulated appearance

In predicting haematoma expansion, one single-centre retrospective study demonstrated that the island sign had a specificity of 98%, sensitivity of 45%, positive predictive value of 93%, and a negative predictive value of 78% 1. Furthermore, the same study demonstrated that the presence of the island sign was an independent predictor of poor outcomes in patients with intracerebral haemorrhage 1.

See also

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