December 6, 2008

Traumatic Aortic Injury (TAI)

Fig.1: Portable chest radiograph shows widening of the superior mediastinum (two-sided arrow), deviation of the NG tube (arrowheads) and trachea to the right.
Fig.2: Axial CT with IV contrast shows a large periaortic hematoma (stars) displacing the NG tube (arrowhead) to the right.
Fig.3: Axial CT at the level below the arch demonstrates a pseudoaneurysm (red arrow) anterior to the true lumen (red arrowhead). Hematoma (stars) and NG tube (yellow arrowhead)

Radiographic Findings

  • Widening of superior mediastinum (subjective 'eyeball' estimation)
  • Blurring of aortic contour
  • Deviation of nasogastric tube to the right
  • Normal - not common but x-ray can be normal if there is no or minimal periaortic hematoma (Normal chest radiograph does not exclude TAI in a trauma patient with suspicious mechanism)

CT Findings
  • Direct signs: Pseudoaneurysm, intimal flap, irregularity of aortic wall, pseudocoarctation, thrombus with in the wall
  • Indirect sign: Periaortic hematoma (not isolated anterior mediastinal hematoma)
Do We Need Aortography?
  • Studies of MDCT (16- and 64-MDCT) showed accuracy of near 100% using surgery or follow-up CT as standard references
  • When a direct sign is present, TAI can be diagnosed confidently without aortography
  • Aortography can be reserved for equivocal cases, evaluation of aortic branch vessels and endovascular therapy
Reference:
1. Kaewlai, et al. MDCT of blunt thoracic trauma. Radiographics 2008 (October)
2. Steenburg, et al. Acute traumatic thoracic aortic injuries: experience with 64-MDCT. AJR 2008 (November)

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