Case of the Day: Case 1

Case of the Day: Case 1


Image 4-108


Image 5-108



Image 4-108: Unenhanced CT demonstrating a peripheral crescentic hyperdense region at the right lateral aspect of a juxtarenal aneurysm.

Image 5-108: Contrast-enhanced CT demonstrating the difficulty in discerning acute blood within the aneurysm wall when IV contrast is present.

Differential Diagnosis:
  • Thrombosed focal dissection
  • Intramural hematoma
  • Pending aortic rupture


The “hyperattenuating crescent sign” is seen best on unenhanced CT and is due to the hyperattenuating nature of acute blood because of the higher concentration of hemoglobin relative to water content. The peripheral crescent results when an acute change allows blood to dissect into the periphery of the mural thrombus, either due to instability of the aneurysm or perhaps causing such instability. The hyperattenuating crescent sign is one of the earliest and most specific imaging findings of pending aortic rupture. Surgical consultation is indicated when this finding is present.

Hyperattenuating signs can be seen in acute arterial occlusion, acute arterial dissection, aneurysm rupture, acute venous thrombosis, etc. The thrombus will measure approximately 50-80 HU on non-contrast enhanced imaging within the first 7 days of bleeding after which the density decreases.

Further reading

Morita, Satoru et al. “Hyperattenuating Signs At Unenhanced CT Indicating Acute Vascular Disease”. RadioGraphics 30.1 (2010): 111-125.


Case courtesy of
Jason DeBerry, MD
Resident PGY-5, UVA

Reviewed by
Patrick Norton, MD
Associate Professor, Non-invasive Cardiovascular Imaging, UVA

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