Q. What is Aortic Enlargement ?

Ascending Aorta: The ascending aorta, along with the SVC forms a portion of the right cardiac border on the PA view. After the age of about 40 years, the ascending aorta may project to the right beyond the SVC. It is often difficult to differentiate age related elongation of the ascending limb from dilatation. On the lateral view, an enlarged ascending limb may encroach on the retrosternal clear space.

Arch: The arch crosses from right to left in front of the trachea and then arches over and behind the left main bronchus, where it lies just to the left of the midline. On the PA view, the aortic knuckle is formed by the distal part of the arch. Again, above the age of 40, the knuckle may be displaced upwards and leftwards.