Focal obliteration of the descending aortic interface on normal frontal chest radiographs: correlation with CT findings.

Abstract

To assess the frequency, location, correlation with age, and cause of partial obliteration of the descending aortic interface on normal frontal chest radiographs. Concurrent chest radiographs and computed tomographic (CT) scans of 1,500 patients in whom CT findings excluded a diagnosis of paraaortic pathologic processes were reviewed retrospectively. Aortic interface obliteration was identified on 134 images (8.9%), which included 43 (2.9%) in the suprahilar and upper hilar portion, 56 (3.7%) in the lower hilar portion, and 46 (3.1%) in the cardiac portion of the interface. The causes were direct contact with or proximity to the aortic margin by pulmonary arteries at the suprahilar and upper hilar portion, superior segment vessels at the lower hilar portion, and various structures, including left inferior pulmonary vein, mediastinal fat, and left ventricle at the cardiac portion. Partial aortic interface obliteration can be seen on normal frontal chest radiographs because of obstruction by small adjacent structures.