Coarctation of the aorta is often identified as an incidental finding following chest radiography. Radiographers who are familiar with the plain film appearances of coarctation of the aorta have the potential to raise this frequently missed finding with the referring practitioner/radiologist.

Rib notching on palin film chest is considered pathognomonic of coarctation of the aorta. Coarctation is the most common cause of rib notching but not the only cause.

http://en.wikipedia.org/wiki/Coarctation_of_the_aorta

"Coarctation of the aorta, or aortic coarctation, is a congenital condition whereby the aorta narrows in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts" Schematic drawing of alternative locations of a coarctation of the aorta, relative to the ductus arteriosus. A: Ductal coarctation, B: Preductal coarctation, C: Postductal coarctation. 1: Ascending Aorta, 2: Pulmonary Artery, 3: Ductus arteriosus, 4: Descending Aorta, 5: Brachiocephalic Artery, 6: Common Carotid Artery, 7: Subclavian Artrey http://en.wikipedia.org/wiki/Coarctation_of_the_aorta

	This patient has presented with RML consolidation. Corctation of the aorta was an incidental finding. Three important findings are Inferior rib notching figure 3 sign of the aorta prominance of the ascending aorta
	Inferior rib notching (white arow) figure 3 sign of the aorta (black arrow) prominance of the ascending aorta
	rib notching

	This patient presented with symptoms of a chest infection. As is often the case, the coarctation of the aorta was an incidental finding. Findings Inferior rib notching figure 3 sign RML consolidation
	Findings Inferior rib notching (small white arrows) figure 3 sign (hollow white arrow) RML consolidation (black arrow) The figure 3 sign is of the type caused by prominance of the left subclavian artery

It has been suggested that the figure 3 sign could be caused by

1. a dilated Left Subclavian Artery
2. a dilated aortic knob,
3. or the “tuck” of coarct itself, and poststenotic dilatation

www.learningradiology.com
These are referred to as a single sign but are infact 3 different entities.