FOCAL OBLITERATION OF THE DESCENDING AORTIC INTERFACE ON NORMAL FRONTAL CHEST RADIOGRAPHS - CORRELATION WITH CT FINDINGS

PURPOSE: To assess the frequency, location, correlation with age, and cause of partial obliteration of the descending aortic interface on no rmal frontal chest radiographs. MATERIALS AND METHODS: Concurrent ches t radiographs and computed tomographic (CT) scans of 1,500 patients in whom CT findings excluded a diagnosis of paraaortic pathologic proces ses were reviewed retrospectively. RESULTS: Aortic interface obliterat ion was identified on 134 images (8.9%), which included 43 (2.9%) in t he suprahilar and upper hilar portion, 56 (3.7%) in the lower hilar po rtion, and 46 (3.1%) in the cardiac portion of the interface. The caus es were direct contact with or proximity to the aortic margin by pulmo nary arteries at the suprahilar and upper hilar portion, superior segm ent vessels at the lower hilar portion, and various structures, includ ing left inferior pulmonary vein, mediastinal fat, and left ventricle at the cardiac portion. CONCLUSION: Partial aortic interface obliterat ion can be seen on normal frontal chest radiographs because of obstruc tion by small adjacent structures.