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Cleft sign

contributed by Dr Frank Gaillard on May 2, 2008

System: Central Nervous System
Section: Signs

The cleft sign can be used to distinguish an extra axial lesion from an intra axial lesion and is typically used in the description of a meningioma.

Classically, the cleft was regarded as representing a thin rim of CSF between tumour and brain parencyma. However, it often is of high signal on FLAIR imaging and most likely represents a non-CSF tumour-brain interface.

Nevertheless, it remains a good sign that a mass is extraaxial and is typically made up of:

  • high T2 signal : (?) CSF (?) other
  • vessels - pial or as in case 1, larger vessels.
  • hypointense dura (on both T1 and T2 on the surface of the mass. (if extra dural)