Tubular artery sign | Radiology Signs

Answer:

The tubular artery sign occurs due to the presence of mediastinal air outlining the mediastinal arteries, most commonly the aortic arch and its branches, such as the left subclavian artery. This sign is seen in pneumomediastinum, a condition where air escapes into the mediastinal space from various causes including alveolar rupture, airway injury, esophageal perforation, or iatrogenic trauma. The radiolucent air sharply delineates the normally soft-tissue-masked contours of these arteries, making them appear as tubular radiolucent structures on plain chest X-ray.

Why is it called so?

It is named the tubular artery sign because mediastinal air outlines the medial side of the artery while the aerated lung marginates its lateral side, producing a tubular-shaped radiolucency corresponding to the artery’s course, creating the appearance of a “tube-like” sign within the mediastinum.

Pathophysiology

Air leaks into the mediastinum from disrupted alveoli or airways, accumulating around and outlining the normal mediastinal arteries. Normally, soft tissues and mediastinal fat obscure the arteries on radiographs, but the infiltrated air creates a sharp contrast between the air and arterial walls, making the arteries visible as tubular lucencies. This radiographic appearance reflects air tracking along anatomical spaces adjacent to these arteries.

Alternative names: None commonly reported.

Other associated named signs: Thymic sail sign, ring around the artery sign, double bronchial wall sign, continuous diaphragm sign, extrapleural sign—all genuine, established signs of pneumomediastinum showing air outlining normal mediastinal structures.

References

1. Bejvan SM, Godwin JD. Pneumomediastinum: old signs and new signs. AJR Am J Roentgenol. 1996.
2. Zylak CM et al. Pneumomediastinum revisited. Radiographics. 2000.