Obstruction of the superior vena cava due to aortic dissection: CT findings of collateral venous flow via the bronchial veins.

Obstruction of the superior vena cava caused by acute aortic dissection can lead to collateral flow in the azygos and hemiazygos system, as well as to reversal of flow in the pleurohilar and bronchial veins. In the latter case, a small right-to-left shunt has formed. We describe the findings in such a case on a contrast enhanced spiral CT.