[Role and limits of x-ray computed tomography and magnetic resonance imaging in acquired diseases of the aorta].

The introduction of computed tomography (CT) and the more recent magnetic resonance imaging (MRI) has radically changed the means of investigating acquired aortic disease by association the visualisation of the blood flow, previously available with angiography, with that of the aortic wall and the surrounding structures of this vessel. The popularity of CT scanning, being nearly non-invasive though dependent on ionising radiation and requiring the injection of contrast, and its diagnostic performance have raised it to the status of a primary investigation for diagnosing aortic aneurysm, especially abdominal, of aortic dissection, its acute complications and postoperative follow-up. However, CT scanning remains unsatisfactory for the examination of collateral and bypass vessels issuing from the aorta and for detailed analysis of aortic trauma and aortitis. MRI, though providing significant diagnostic advantages by the 3 dimensional visualisation of the aorta, the presence of spontaneous contrast between the lumen and vessel wall and cine MRI, is still relatively little used because of the small number of installations dealing with this indication in France. Despite the limitation, this totally non-invasive and non-irradiating investigation is progressively extending its use for the diagnosis of certain subacute or chronic aortic diseases. MRI is the best non-invasive investigation for the diagnosis of thoracic aortic aneurysms, chronic or subacute aortic dissection and for repeated postoperative follow-up after thoracic aortic surgery. Technological advances of this new imaging method and the multiplication of the number of installations suggest that the field of application of MRI for disease of the aorta will steadily increase in the future.