POSTAORTIC LEFT INNOMINATE VEIN - RADIOLOGICAL ASSESSMENT AND PATHOGENESIS

Postaortic left innominate vein (PALIV) is a rare venous anomaly and t he findings on plain chest radiographs have not been well described. P lain chest radiographs, CT and MR of nine adults known to have PALIV w ere reviewed. They all showed a high aortic arch, including four with a right-sided aortic arch and one with a double aortic arch, in poster o-anterior radiographs, and seven showed curved shadows in the left up per mediastinum. On all lateral chest radiographs (n = 5), the superio r retrosternal region was opacified by the high aortic arch. CT or MR images confirmed the aortic arch and/or innominate artery to be in tha t part of the retrosternal space, normally occupied by the left innomi nate vein, in all cases. Association of a curved shadow in the superio r mediastinum with a high aortic arch on plain chest radiographs is th erefore suggestive of, though not diagnostic for, PALIV. This entity w as well documented by CT or MR and the radiological findings were cons idered to imply that developmentally PALIV is secondary to a high posi tion of the aortic arch.