MR of right aortic arch with mirror-image branching and a left ligamentum arteriosum: an unusual cause of a vascular ring.

An unusual case is presented of a vascular ring due to a right arch with mirror-image branching and a left ligamentum arteriosum from the descending aorta to the left pulmonary artery. There have been only four previous reports of this rare arch anomaly. In addition, the patient had no underlying congenital heart lesions, which is also very unusual in patients with right aortic arch with mirror-image branching.