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Empty delta sign

NeuroCT / MRI (contrast)

On contrast-enhanced imaging the superior sagittal sinus shows an enhancing triangular wall with a non-enhancing filling defect at its centre.

What it means

Dural venous sinus thrombosis, most often of the superior sagittal sinus.

Mechanism

Enhancing dura and collateral flow surround a central non-enhancing thrombus, producing an empty triangle on axial images.

Associated conditions

  • Cerebral venous sinus thrombosis
  • Hypercoagulable states
  • Pregnancy and puerperium
  • Dehydration or infection

Pearls

  • It is best appreciated on contrast-enhanced CT or MR venography.
  • A dense clot may also be seen as a hyperdense sinus on unenhanced CT (the cord sign).

References

  • Radiopaedia: Empty delta sign

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.