Imaging description

The medial layer of the aorta expands in intramural hematoma (IMH) due to the accumulation of subacute blood products. The expansion can shear the wall of exiting arteries such as the intercostal and lumbar arteries.

Contrast collects between the sheared wall of the intercostal artery and the medial layer of the aorta. The contrast collection is beyond the confines of the arterial lumen but the pooled contrast is well localized (Figures 61.1 and 61. 2).

The shearing of the intercostal arteries is also called the “Chinese Ring Sword Sign”.

Importance

This entity can be confused for active extravasation.

In vascular imaging, active extravasation of contrast has important connotations. It means that there is active bleeding. The use of the present participle (bleeding) as opposed to the past tense (bled) elevates the clinical severity and urgency of the vascular process and the promptness with which corrective action is required. Both inappropriate usage and inappropriate non-usage of this term by imagers can have negative consequences.

Typical clinical scenario

Patient presents with chest or back pain with suspicion of an acute aortic syndrome.

Differential diagnosis

Active extravasation is inferred when there is contrast outside the confines of a vascular structure; the contrast outline does not conform to the shape of an arterial branch of venous tributary. Typically the contrast progressively pools in the arterial and venous phases of acquisition.

The pooled contrast can mimic false lumen of a dissection. It can also mimic a penetrating atherosclerotic ulcer.

Teaching point

Mistaking the pooled contrast from sheared vessels for active bleeding can lead to inappropriate operative intervention. IMH of the descending aorta is typically managed medically.