Signet Ring Sign: A CT Hallmark of Bronchiectasis

The signet ring sign on CT—a dilated bronchus adjacent to its pulmonary artery—indicates bronchiectasis. Recognizing this classic sign helps avoid missed diagnosis.

• The signet ring sign is formed by a dilated, thick-walled bronchus (the "ring") and its adjacent pulmonary artery branch (the "stone").
• It is best appreciated on thin-section CT and is a highly specific sign for bronchiectasis.
• This teaching point from LearningRadiology reinforces pattern recognition for chest imaging.

Automated summary

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