Magnetic Resonance Imaging and Asymptomatic Aortic Dissection
Aortic dissection is a well-known complication of Marfan syndrome. Aortic dissection in patients with Marfan syndrome is associated with aortic root dilatation. As imaging techniques have improved, it has become clear that some patients with Marfan syndrome, in the absence of symptoms, may have evidence of a prior aortic dissection. A 47-year-old white man with documented Marfan syndrome and no prior symptomatology referable to aortic dissection had elective high-resolution MRI of the aorta for an unrelated research project. Importantly, he had no known risk factors for atherosclerotic disease. The MR images showed that his aortic root was not dilated, with a diameter of 36 mm (Figure 1A⇓). His ascending aorta was not dilated, with normal wall thickness and no evidence of an intimal flap (Figure 1B⇓). However, a small defect was evident in the wall of the descending thoracic aorta that was more readily appreciated on magnified views of the region (Figure 2⇓). Proton density–weighted (Figure 2A⇓) and T2-weighted (Figure 2B⇓) images clearly showed a very small but distinct defect within the aortic wall, consistent with a false lumen. Review of the complete series of MR images confirmed a small, limited type B dissection, beginning just beyond the origin of the left subclavian artery and extending distally into the descending thoracic aorta for ≈5 cm. No communicating channels were identified between the 2 lumens.
With improvements in vascular imaging techniques that permit high-resolution noninvasive analysis of the arterial wall, we may find more asymptomatic, previously undetected aortic dissections in patients with Marfan syndrome. Generally, it has been assumed that this occurs in association with aortic root dilatation; in this case, however, the dimensions of the aortic root were within normal limits. The natural history of this phenomenon in patients with Marfan disease is unclear.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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