When damage occurs to the wall of a normal blood vessel and bleeds into body tissues, clotting blood generally causes the hemorrhage to stop. Leaked blood disperses and is slowly re-absorbed. However if damage occurs to the inner layer of the vessel whilst the soft, thin outer coating is unbroken, the pressure of blood into the area may cause the thin tissue layer to blow up like a balloon and form a cavity. Pressure does not allow the space to collapse, blood swirls around keeping it open and, indeed, increasing its size. This is known as a pseudo-aneurysm.
The Chest X-ray in this image is from a 40-year-old driver one month after a major accident. He complained of a swelling above the right collarbone (clavicle) and was unable to move his right arm. An X-ray study of the artery – an angiogram – showed a large pseudo-aneurysm.
In my image, I have overlaid the man’s chest X-ray with the angiogram study of the arteries of his right arm. The artery and the aneurysm are depicted in multiple layers and I have used the colour scheme to indicate the dangerous nature of this condition.