Imaging description

In some patients, fluid in the anterior portion of the superior aortic recess of the pericardium can extend cranially and abut the aortic arch and the arch branch vessel origins. In patients being evaluated for trauma with multidetector CT, this fluid may be mistaken for periaortic hematoma (Figure 58.1). However, unlike hemorrhage, fluid in a pericardial recess will measure simple fluid attenuation and will have sharp, well-defined borders. Pericardial fluid abuts the aorta and great vessels without an intervening fat plane. Patients with acute aortic injury and hematoma will have high-attenuation fluid next to the aorta and a contour abnormality or intimal flap within the aorta itself.

Importance

Misdiagnosis of traumatic aortic injury could lead to inappropriate invasive catheter angiography or surgery.

Typical clinical scenario

Fluid in the superior aortic recess is common and may be encountered in patients with or without an associated pericardial effusion.

Differential diagnosis

In the setting of trauma, fluid in the superior pericardial recess can mimic periaortic hemorrhage; however, these entities can usually be distinguished by attenuation measurements (Figure 58.2). Fluid collections in the superior aortic recess simulating lymphadenopathy or aortic dissection have also been described.

Teaching point

Fluid in the anterior portion of the superior aortic recess abutting the aortic arch can mimic periaortic hematoma. Measurement of fluid attenuation values and close inspection of the aorta for contour abnormalities or intimal injury will help avoid misdiagnosis.