CT characteristics of aortic atherosclerotic aneurysm versus aortic dissection.

In an attempt to better define criteria for the diagnosis of atherosclerotic aneurysm (AA) and aortic dissection (AD) using CT the scans of 60 documented aortic lesions were reviewed. Hyperdensity of the aortic wall at multiple levels was found to be specific for AD. Central displacement of atheromatous calcification and deformity of the residual aortic lumen were more common in AD than in AA. Peripheral location of aortic wall calcification and a round aortic lumen in cross section were more common in AA than in AD. Central calcification in AA appeared to be associated with a serious short-term prognosis in several cases. A thickened aortic wall of low density was more common in AA than in acute AD, but this relationship was not significant when acute and chronic ADs were considered as a single group. Wall thickness correlated with cross-sectional size of the aortic lesion in AA but not in AD. The mean maximum wall thickness exceeded 1 cm for both AA and AD and was not significantly different between the two; contrary statements have been made in the angiographic literature.