Ten abdominal aortic aneurysms were totally, or subtotally resected and twenty nine preoperative transverse ultrasonograms of them were studied in comparison with the corresponding ultrasonograms and cross sections of their surgical specimens.
Outermost dense fibrous walls of the aneurysms were demonstrated as moderately strong echo lines. The delineation rates of each part of the wall were 86% in the right-posterior part, 59% in the posterior part, and 10 to 31% in the others. Compound scannings with echo beams directed right-posteriorly were useful to delineate the right-posterior part.
Both mural thrombi and atheromas of the aneurysm were usually represented as relatively weak echo areas. In the anterior half of the aneurysm, both of them thicker than 1.4 cm, seen in five cases, were all delineated but none of those thinner than 1 cm. In the posterior half, both of them thicker than 1 cm, seen in five cases were all delineated, but not all of those thinner than 1 cm. Atheromas thicker than 1 cm, seen in three cases, were partly represented as echo free areas.
Clear delineation of the structures of the aneurysms were often interfered by the reverberation artifact, echos of the surrounding structures, and the lateral acoustic shadows.