Presentation
Chest pain. CTPA negative for PE. Patient went for coronary catheter angiogram due to raised troponin. RCA stenosis treated with stenting. Incidental finding on CTPA.
Patient Data

Dense contrast from the automatic injector (from the right arm) fills the SVC and refluxes into the terminal portion of the azygos arch, distending the sinuses of a venous valve which is preventing reflux further down the azygos vein.
Case Discussion
This case nicely demonstrates the location of the valve of the azygos arch.
The valve can be seen in about 2/3rds of cases with reflux of contrast into the azygos arch 1. The most proximal valve is often found within 4 cm of the SVC and when present and seen with contrast reflux is often (82%) associated with a bulge of the valve sinus. Contrast isolated in the sinuses of this valve may be mistaken for hyperattenuating foci in the vicinity such as calcified lymph nodes, surgical clips or tracheal calcification.