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Ivy sign

NeuroMRI (FLAIR / post-contrast)

Leptomeningeal high signal on FLAIR (or enhancement) coating the cortical sulci, likened to ivy creeping over stones.

What it means

Slow leptomeningeal collateral flow, characteristic of moyamoya disease.

Mechanism

Sluggish flow in engorged pial collaterals over the cortical surface produces the sulcal FLAIR hyperintensity and enhancement.

Associated conditions

  • Moyamoya disease
  • Moyamoya syndrome
  • Chronic large-artery steno-occlusion
  • Ischaemic borderzone states

Pearls

  • The ivy sign reflects impaired cerebrovascular reserve in moyamoya.
  • Look also for basal ganglia collateral vessels (the puff-of-smoke appearance) on angiography.

References

  • Radiopaedia: Ivy sign (moyamoya)

For educational use only. This dictionary is a study aid and reference, not a diagnostic tool, and must not be used to guide clinical decisions or patient care. Imaging appearances vary; always correlate with the full clinical picture and confirm with a qualified radiologist.