Thoracic spine sign (ultrasound)

The thoracic spine sign on lung ultrasound is an indirect indicator of the presence of a pleural effusion or haemothorax. It represents the visualisation of the vertebral bodies in the thoracic cavity above the diaphragm which are usually not seen unless there is a fluid collection. 

Radiographic features

Ultrasound
Technique

A curvilinear or low-frequency probe can be used and is placed longitudinally in the lowest or dependent area of the lung where fluid tends to collect. This corresponds to the right or left upper quadrant views similar to that of a FAST scan. The diaphragm is identified, below which vertebral bodies can be seen as hyperechoic or bright white structures 1.

Normal Findings

When no pleural fluid is present, there is a sharp cut-off of the vertebral bodies at the level of the diaphragm, above which they cease to be seen due to air in the lungs impeding the transmission of ultrasound waves; hence deeper structures (namely the vertebral bodies) can not be visualised 1

Thoracic spine sign

In the presence of a pleural fluid collection, the transmission of ultrasound waves is enhanced, allowing us to visualise the presence of the vertebral bodies; which are seen as a continuous hyperechoic line extending both above and below the diaphragm 1

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Article Information

rID: 50946
System: Chest
Section: Signs
Synonyms or Alternate Spellings:

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