The portable anteroposterior chest radiograph is the initial radiographic screening. It may reveal loss of the aortic knob contour, left-sided pleural effusions, mediastinal widening, nasogastric tube deviation, or tracheal deviation, all of which suggest injury to a great vessel. Other findings suggestive of such an injury include depression of the left mainstem bronchus, left apical capping, narrowing of the carinal angle, sternal fractures, opacification of the aortopulmonary window, and widening of the paraspinous stripe.