MRI in typical and atypical aortic dissection

To determine the value of MRI in typical and atypical aortic dissections. Methods: MRI investigations on 16 patients with aortic dissections were analysed retrospectively; for 8 patients CT investigations carried out at almost the same time were available for comparison. Results: In all cases the diagnosis of aortic dissection was possible from MRI and CT. If a dissection membrane and a double lumen were present these were detected in all patients by both methods. In three patients with atypical dissections, only an asymmetrical abnormal wall thickening as sole sign for the presence of an aortic dissection was seen. A differentiation between true and false lumen was possible in 16 of 17 MRI investigations and in 5 of 8 CT investigations on the basis of differing blood flow velocities or, respectively, the detection of a thrombus in the false lumen. The relationship of the dissection membrane to the large aortic branches as well as the determination of the branch vessel origin with regard to true or false lumen could be evaluated better with MRI than with CT. Conclusions: Thus MRI has a significant role in the diagnosis and follow-up of aortic dissections. The advantage in comparison to the alternative spiral CT technique is, in addition to the absence of radiation exposure, the better analysis of the extent of the dissection as a result of the multi-planar slice orientation (especially in the region of the aortic arch and the arch vessel origins) without the necessity to administer iodine-containing contrast media. (orig.)