Radiographic findings of aberrant right subclavian artery initially depicted on CT.

Purpose: To evaluate the radiographic findings of aberrant right subclavian artery (ARSCA) initially depicted on CT.
Methods: Twenty-five cases incidentally diagnosed during CT between June 1993 and May 2001, were examined. They included 13 men and 12 women aged from 29 to 84 years old (mean, 63 years). Three findings were evaluated on posteroanterior radiographs: 1) oblique edge, 2) vessel through the trachea, and 3) mass effect. On lateral radiographs, the following findings were evaluated: 1) posterior tracheal imprint, 2) retrotracheal opacity, and 3) aortic arch obscuration.
Results: On the posteroanterior radiographs, oblique edge, vessel through the trachea, and mass effect were observed in 32% (8/25), 44% (11/25), and 20% (5/25) of cases, respectively. On the lateral radiographs, posterior tracheal imprint, retrotracheal opacity, and aortic arch obscuration were observed in 95% (18/19), 58% (11/19), and 37% (7/19), respectively. On posteroanterior radiographs, normal cases were most frequent (40%). In contrast, lateral radiographs demonstrated at least one abnormality in all cases. As a variation of posterior tracheal imprint, the long-segment type of compression was observed in 32%.
Conclusions: We consider detailed interpretation of the posterior tracheal edge on lateral radiographs to be important in diagnosing cases of mild ARSCA.