RADIOLOGY: AORTA: Case# 30: PSEUDOCOARCTATION. 40 year old male with a mediastinal mass on chest radiograph. There is marked tortuosity of the aortic arch with kinking of the mid-portion of the arch. These findings are best appreciated on the reconstructed coronal image. Pre- and poststenotic dilatation of the arch is present. Pseudocoarctation represents kinking of the aortic arch rather a true coarctation. The ascending aorta is usually normal in position and caliber. The aortic arch, however, is higher than normal. As the arch descends, it courses anteriorly then curves posteriorly toward its normal course producing the characteristic kink in the aorta. The left subclavian artery may arise more distally than usual.