Magnetic resonance imaging of aneurysms and chronic dissections of the thoracic aorta.

Magnetic resonance imaging (MRI) was performed in 30 patients having an aneurysm or chronic dissection of the thoracic aorta. Using a magnetic field of 0.5 Tesla, multislice image acquisition was obtained by the ECG gated spin-echo imaging technique with dual-echoes. These results were retrospectively compared with those obtained in the same patients by angiography and computerized tomography (CT). In 10 cases of aneurysm, MRI measured their diameters and residual lumina and assessed the extension of the aneurysm with the same precision as CT scan and angiography. In 17 other cases, the diagnosis of chronic dissection was made by documenting an intimal flap and double channel filling of the aorta, and MRI compared favorably with CT scan. In three dissections in which the false lumen was thrombosed, MRI was unable to distinguish between dissection and partially thrombosed aneurysm. We believe MRI constitutes a useful noninvasive method for the study of aneurysms and chronic dissections of the thoracic aorta.