A 29-year-old postpartum woman presents with severe headache and seizures. Contrast-enhanced CT head demonstrates a triangular filling defect within the enhanced superior sagittal sinus. What is this sign called?
- A Dense triangle sign
- B Spot sign
- C Delta sign (empty delta sign) ✓
- D Target sign
Correct answer: C. Delta sign (empty delta sign)
Explanation
The empty delta sign is pathognomonic of superior sagittal sinus thrombosis on contrast-enhanced CT: dural collateral channels enhance around the non-enhancing thrombus, leaving an unfilled triangular center. The dense triangle sign is the unenhanced counterpart, seen when the thrombosed sinus itself appears hyperdense before contrast. The spot sign refers to active extravasation within an intracerebral hematoma, and the target sign describes toxoplasmic lesions, both unrelated entities.
Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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