Thoracic aortic dissections: magnetic resonance imaging.

Abstract

Six patients with documented dissections of the thoracic aorta (2 Type A, 4 Type B) were examined by magnetic resonance (MR) imaging using a 0.6-Tesla superconductive magnet. Cardiac gating was applied in 5 cases. Correlation was made with CT [computed tomography] and angiography. MR imaging demonstrated the dissection in all 6 cases and accurately differentiated Type A from Type B dissections. Coronal and sagittal MR sections were advantageous in establishing the relationship of the 3 arch vessels to the dissection. In addition, cardiac-gated MR was useful in demonstrating mural thrombus and in distinguishing the true from the false lumen based on differences in signal intensity resulting from different flow rates. In 5 cases, the information obtained by MR was equal to or surpassed that obtained by CT. In the 1 case of a completely thrombosed dissection, the CR scan was more helpful. MR should become an important imaging modality in the evaluation of arotic dissections.