Posterosuperior mediastinal widening in aortic coarctation.

Lobular widening of the posterosuperior mediastinum above the level of the aortic arch was noted in 17 (35.4%) of 48 patients with coarctation of the aorta. The incidence of this finding increased with age. The lobular widening of the lung-mediastinal interface is produced by short collateral pathways consisting of anastomoses of the first and second posterior intercostal arteries and branches of the inferior thyroid arteries with the third and fourth posterior intercostal arteries. Although this soft-tissue abnormality is usually associated with inferior rib notching (Roesler sign), the plain-film finding may be seen without rib notching; also, rib notching may occur without any detectable change in the lung-mediastinal interface. In this series, lobular widening of the superior mediastinum was the fourth most common accessory sign of aortic coarctation.