Fig. 11
From: Blood finds a way: pictorial review of thoracic collateral vessels
Blockage of the SVC below the azygos vein. a Schematic image of a SVC obstruction at the level of the azygos vein and pathway for collateral flow. b Coronal CT image shows occlusion of the SVC below the level of the azygos vein (white arrow). c Axial CT image demonstrates retrograde contrast flow through the azygos vein (gray arrow) from the upper SVC (white arrow). d Axial CT image showing diaphragmatic collaterals (curved arrow) draining to the IVC (arrowhead) bypassing the inferior SVC blockage below the level of the azygos vein