[Computed tomographic diagnosis of dissecting aneurysm of the aorta]

Twenty-four patients with dissecting aortic aneurysms have been examined by CT and possible causes of mistaken diagnosis are discussed. Failure to diagnose a dissection by CT may be due to atypical localisation and thrombosis of the aortic dissection; dissections of small volume, particularly in the ascending aorta; failure to demonstrate an intimal flap and inadequate contrast enhancement. A false positive diagnosis may be due to fibrotic, inflammatory or neoplastic periaortic changes, aneurysm of the sinus of Valsalva, or artifacts.