Imaging description

In patients with prior cardiothoracic surgery requiring cardiopulmonary bypass, felt pledgets are used to ensure hemostasis during closure of cannula sites in the ascending aorta. On imaging, these pledgets are high attenuation and are located immediately adjacent to the aortic wall in the high ascending aorta (Figure 66.1). Sometimes on axial source images these high-attenuation foci can mimic small pseudoaneurysms. Correct diagnosis of surgical material can be made by inspection of volume-rendered images, which will often show a rectangular shape (Figures 66.1 and 66.2). Non-contrast images, if available, will also be helpful for showing pledgets as highattenuation precontrast (Figure 66.1).

Importance

Misdiagnosis of pseudoaneurysm of the ascending aorta can lead to inappropriate additional follow-up scans or, in the worst case scenario, repeat surgery.

Typical clinical scenario

Felt pledgets are used for suturing of cannula sites when cardiopulmonary bypass is used, such as for cardiac surgery or thoracic aortic repair.

Differential diagnosis

Surgical material should be distinguished from true aortic pseudoaneurysms, which can occur at cannula sites or anastomoses due to suture break down after thoracic surgery. These will be recognized by a narrow-necked connection to the aortic lumen and attenuation that is similar to blood pool on both pre- and post-contrast imaging.

Teaching point

Felt pledgets adjacent to the ascending aorta in patients with prior cardiothoracic surgery should not be mistaken for pseudoaneurysms. High attenuation on precontrast scans and characteristic shape on volume-rendered reconstructions will allow definitive diagnosis.