This X-ray shows a semilunar shadow of intimal calcification in aortic knuckle (yellow arrow). The position of this calcification can be helpful in the diagnosis of:
b) Aortic aneurysm
c) Aortic dissection
d) None of the above
Answer: c) Aortic dissection
Calcification of the intima of aortic knuckle (arrow) is a common finding in the elderly. Usually it is of no significance. But a separation of the intimal calcification from the edge of the aortic knuckle shadow indicates a separation of the intima from the media as in aortic dissection. This has been called the “calcium sign” in aortic dissection. A separation of more than 1 cm is considered significant.