Dynamic CT and MRT were performed in 21 patients who had undergone prosthetic replacement of the aorta because of dissection of the thoracic aorta. There is no difference between MRI and dynamic CT in the demonstration of a persistent intimal flap, the formation of a thrombus and the assessment of the aortic diameter in patients who underwent surgery for thoraco-abdominal aortic dissection. MRI, however, is superior in the identification of the true and false lumen and the demonstration of the distal anastomotic site. The major advantages of MRI are that there is no need for intravenous contrast agents, that it is highly sensitive to flow phenomena, and that it can demonstrate the aortic arch and the ascending aorta on sagittal oblique sections. The major disadvantages of MRI are the limited access to the patient during the procedure, and the inability to examine patients fitted with pacemakers or who are on assisted ventilation. Today, MRI is considered the method of first choice for the postoperative follow-up of patients who underwent surgery for aortic dissection.

Para-aortic pseudoaneurysms after prosthetic replacement of an aortic valve was diagnosed by magnetic resonance imaging (MRI) in two patients and confirmed at surgery. The abscesses had not been visualized in either case by computed tomography and echocardiography, but in one it had been demonstrated by angiography. MRI can thus precisely define site and extent of a para-aortic pseudoaneurysm after aortic valve replacement without any interference by artefact, noninvasively and without use of contrast media.

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