"Pseudocoarctation" of the aorta: pitfall on cine MR imaging.

The diagnosis of coarctation of the aorta on cine magnetic resonance imaging is based upon observation of localized narrowing in the region of the aortic isthmus with jet-like signal void areas extending distally. We observed similar findings in 8 of 20 (40%) normal volunteers examined in the sagittal oblique view. These artifactual findings relate primarily to out-of-plane motion of the thoracic aorta during a portion of the cardiac cycle, leading to partial volume averaging with pulmonary air. Awareness of this pitfall will prevent misdiagnosis of aortic coarctation in normal subjects and allow for more accurate assessment of severity of true coarctation.