Magnetic Resonance Phase Velocity Mapping in Dissecting Aortic Aneurysm
Demonstration of a Proximal Intimal Tear
A 57-year-old man with a history of a dissecting aortic aneurysm 4 months previously was referred for magnetic resonance imaging. Transthoracic echocardiography, transesophageal echocardiography, and ultrafast computed tomography had demonstrated the dissection extending from the ascending aorta to the renal arteries. The point of entry was thought to be just above the aortic valve, but it had not been satisfactorily demonstrated by any of these imaging modalities. Magnetic resonance imaging was requested before surgical repair in an attempt to identify the proximal tear.
Gradient echo imaging (echo time, 14 ms) in the coronal plane clearly demonstrated the intimal flap arising just above the aortic valve, but it was not possible to identify the entry site (Fig 1⇓). A series of transverse gradient echo cines were acquired to identify any small area of signal loss at the intimal flap. At a level at which there appeared to be some turbulent flow, an oblique coronal gradient-echo cine was acquired across the intimal flap and through the area of signal loss. The systolic frames of this cine demonstrated an area of signal loss in the false lumen that was suggestive of a jet but could have represented turbulent flow within the false lumen (Fig 2⇓). Phase velocity mapping performed in the same plane (echo time, 3.6 ms) clearly showed a jet from the true lumen to the false lumen through an intimal tear measuring approximately 12 mm at a level 3 cm above the aortic valve (Fig 3⇓).
Reprint requests to Dr Sandy Forbat, Magnetic Resonance Unit, Royal Brompton Hospital, Sydney St, London SW3 6NP, England.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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