Fig. 10

Blockage of the SVC at the level of the azygos vein. a Schematic image of a SVC obstruction at the level of the azygos vein and pathway for collateral flow. b Axial CT image in a patient with a right hilar mass at the level of the SVC/azygous junction, causing the azygos vein (gray arrow) to become dilated. c Coronal CT image in the same patient demonstrating a prominent azygos vein (gray arrow) shunting blood inferiorly toward the IVC. d Blood from the azygos system in this patient is eventually shunted through collateral vessels (dashed arrow) into the IVC (arrowhead) bypassing the SVC blockage at the level of the azygos