OVERVIEW OF TRAUMATIC INJURY OF THE THORACIC AORTA

Traumatic injury of the thoracic aorta is a major clinical concern in patients who sustain deceleration or crush injuries. Several mechanica l factors may explain the typical locations of thoracic aortic rupture (aortic isthmus, ascending aorta). Understanding these factors and th e pathophysiology involved helps the radiologist to recognize aortic t rauma at various imaging examinations. Chest radiography is the initia l screening examination, and radiographs are evaluated specifically fo r signs of mediastinal hematoma, an indication of significant thoracic trauma. The most important of these signs include loss of aortic cont our, tracheal deviation, ratio of mediastinal width to chest width, de viation of a naso-gastric tube to the right of the T-4 spinous process , and depression of the left main-stem bronchus (> 40 degrees below th e horizontal). Computed tomography (CT) is used increasingly when resu lts of chest radiography are equivocal. CT can clearly demonstrate med iastinal hematoma, but this finding is also mimicked by several entiti es, including atelectatic lung, thymus, and pericardial recesses. Aort ography is the standard for diagnosis. Traumatic aortic injury is trea ted urgently with surgical repair. The rare patient who survives aorti c injury without surgery may develop a chronic pseudoaneurysm.