Imaging description

Blunt traumatic aortic injury is often, but not always, associated with mediastinal widening and aortic contour abnormalities on chest radiography (Cases 40 and 41) Most, but not all, patients with blunt thoracic aortic injury (BTAI) and an aortic pseudoaneurysm will have periaortic hematoma on the abdominal CT (Figures 42.1 and 42.2). In one retrospective study, 11/14 CTs of the abdomen in patients with known BTAI demonstrated periaortic hematoma in the retrocrural region [1]. In another study, 14/20 patients with confirmed BTAI had periaortic hematoma [2]. Overall, the sensitivity for the detection of BTAI in these studies was 70% and 88% [1, 2].

Importance

The importance of periaortic hematoma is that it is a marker of potential aortic injury. Patients with a blunt trauma mechanism that is compatible with traumatic aortic injury should undergo CT angiography (CTA) of the thoracic aorta to exclude BTAI.

Typical clinical scenario

Blunt thoracic aortic injury is a highly lethal injury. Up to 80% of patients with BTAI die at the scene. It is diagnosed in less than 0.5–2% of non-lethal motor vehicle collisions. Based on the historic work of Parmley, we know that unrecognized and untreated aortic injury has a high mortality, with a 1% mortality rate per hour for the first 48 hours after admission [3]. Fortunately, CTA of the chest, and whole body CT are now commonly performed to evaluate patients at risk of BTAI and survival is greatly improved [4]. Signs of chest injury (e.g., thoracic cage fractures, pneumothorax, pulmonary contusions, or diaphragmatic injury) are present in most patients with BTAI who undergo chest radiography as the initial evaluation following major trauma. However, these signs can be subtle, or even absent, particularly in young patients who have a more pliable chest wall [5]. A