[Late phase contrast enhanced-CT analysis of thrombosed type aortic dissection].

Seven patients with thrombosed type aortic dissection who underwent both early- and late-phase contrast enhanced (CE)-CT scans were analyzed. The image acquisition of early-phase CE-CT began 30 seconds after the intravenous administration of contrast material at an injection rate of 1.5 ml per second. Late-phase CE-CT began 6 minutes after contrast material injection. The thrombosed false lumens were not enhanced on early-phase CE-CTs in any of the cases. In five of seven cases, on the other hand, false lumens of the descending aorta were enhanced on late-phase images. Late enhancement in the false lumen was roughly divided into two patterns; (1) a crescentic enhancement of the sub-adventitial region (3 cases), and (2) a vague enhancement around the ulcerlike projection (2 cases). The mechanism of late enhancement in the false lumen was not fully elucidated. Although the clinical significance of late enhancement has not yet been established, it will be useful to demonstrate an unstable status of the thrombosed false lumens before organization.