Yin-yang sign (vascular)

The yin-yang sign, also known as the Pepsi sign, is a radiological sign described in both true and false aneurysms on various imaging modalities.

Radiographic features

Ultrasound

On Doppler ultrasound, the yin-yang sign indicates bidirectional flow due to the swirling of blood within the true or false aneurysm.

CT

There is no exact correlate for the sign on CT. The patent lumen of the aneurysmal vessel demonstrate contrast enhancement, whereas any low-flow or thrombosed portions may show reduced attenuation.

History and etymology

It is named after the symbol representing the Chinese philosophers' thoughts to describe how opposing forces are interconnected and interdependent.

It has also been likened to the logo for Pepsi®, the well-known cola beverage.

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Article information

rID: 17024
System: Vascular
Section: Signs
Tag: refs
Synonyms or Alternate Spellings:
  • Pepsi sign
  • The Yin-Yang sign
  • The Yin and Yang sign
  • Ying-yang sign
  • The ying-yang sign

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Cases and figures

  • Figure 1: diagram: the yin-yang sign
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  • Case 1
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  • Case 2
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  • Case 3: on video
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  • Case 4: the yin-yang sign on CT
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  • Case 5
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  • Case 6
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  • Case 7
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  • Case 8
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  • Case 9
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  • Case 10
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