Knuckle sign (pulmonary embolism)

Knuckle sign refers to the abrupt tapering or cutoff of a pulmonary artery secondary to embolus. It is better visualised on CT pulmonary angiography scan than chest x-ray. This is an important ancillary finding in pulmonary embolism (PE), and often associated with the Fleischner sign of dilated central pulmonary arteries. 

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Article Information

rID: 41201
System: Chest
Section: Signs
Synonyms or Alternate Spellings:
  • Knuckle sign: pulmonary embolism
  • Knuckle sign in pulmonary embolism

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