The Somatom Plus for Aortic Dissection: A 4-Year Review

Abstract

The first reports of the use of computed tomography (CT) for the diagnosis of aortic dissection were announced in the early 1980s. A milestone paper at that time was by Thorsen et al. (1983) who reported excellent results using a technique which evaluated the aorta during a bolus enhanced sequence of images obtained at three separate anatomical levels. However, data acquisition times were then in the region of 5 s and were limited by an inherent 5 s interscan delay in order to allow tube cooling. Various artefacts were reported and became recognised as potential pitfalls. The value of close scrutiny of unenhanced images was emphasised: around 50% of acute dissections can be predicted before enhancement because of high attenuation material within the false lumen (Heiberg et al. 1985). This knowledge can assist the choice of anatomical sites for subsequent enhancement. There followed occasional reports of very thin dissection flaps being obscured by a combination of the dense contrast medium and their extreme mobility during the 5 s data acquisition. CT for the detection of dissection then started to be applied in non-specialist centres, which often had to struggle with less than ideal equipment. The inevitable (although occasional) misleading resuls led to some anxiety on the part of clinicians. Some centres still insist on a second test before definitive surgery. The second test has historically been aortography, on the grounds that the aortic valve, the coronary arteries and the longitudinal extent of the dissection can be readily evaluated. Much depends on the working practice of the surgeons at individual centres.