Island sign

Last revised by Joshua Yap on 09 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 hematoma expansion and prognosis in patients with intracerebral hemorrhage 1. It is posited that the small islands of hematomas represent multiple sources of hemorrhage from injury to adjacent arterioles. 

The island sign is defined as either 2:

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

In predicting hematoma expansion, one single-center 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 hemorrhage 1.

See also

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