Nontraumatic Disorders in Mediastinum and Thoracic Aorta: Chest RadiographicFindings

ABSTRACT

BACKGROUND: Rupture of thoracic aortic aneurysm and dissection into the chest space results in the death of the patient from uncontrolled hemorrhage. The purpose of our study is to evaluate chest radiographic findings that may assist in the rapid detection of nontraumatic disorder in mediastinum and thoracic aorta. MATERIAL AND METHOD: Thirteen consecutive chest radiographs obtained at emergency room of patients with hemorrhage from ruptured thoracic aortic aneurysms or aortic dissections were randomized with radiographs of 8 subjects with nonruptured thoracic aortic aneurysms, 11 subjects with nonruptured aortic dissections, and 20 control subjects. Diagnoses were confirmed by computed tomography(CT) and transesophageal echocardiography(TEE). A retrospective study was performed by assessment of 14 parameters on each of these 52 radiographs to screen the mediastinum and thoracic aortic disorder. RESULTS: Significant difference between patients with mediastinum and thoracic aortic disorder(aneurysm and dissection) and normal subjects occurred in mediastinal/chest ratio>0.25, aortic knob width>4cm, tracheal shift to right loss of paratracheal stripe & azygos vein, and left pleural & extrapleural fluid of chest radiographs(p<0.05). The most useful predictors of mediastinum and thoracic disorder were aortic knob widening above 4cm and combining signs of mediastinum/chest ratio above 0.25 and abnormal aortic arch. These plain radiographic signs had a sensitivity of 9.1~96.9% and a specificity of 40~100% for mediastinum and thoracic aortic disorder. CONCLUSION: The chest radiograph obtained at emergency room remains the best available screening test for mediastinum and thoracic aortic disorder and can be used effectively, though not perfectively, to eliminate unnecessary CT or TEE.