these images of the azygous are an emphatic illustration of the difficulties of interpretation and the wide variation in rates of incidence of azygous disease stated by different operators.
Some of these images look like they were taken in a shallowe obliquity of the azygous vein. While imaging of the Ascending portion of the azygous vein is not dependend upon the view, images of the arch are very sensitive to the angle taken. The views of this vein seem to foreshorten the azygous vein. that means that we are looking right down the barrel of the vein. everything is telescoped on to itself and nothing can be clearly seen because everything is superimposed.. The anterior and the posterior portions of the arch are superimposed. These are the areas of the vein where truncular malformations are going to be situated. thus, this view is unreliable.
my research has shown that the best views for the arch are 70 and 90 degrees. but sometimes more than these two views are required
Other difficulties of looking at these images are the fact that the lung tissue and bronchial tubes are moving during these images. Subtraction is the technique wherein everything on the screen before injection of the xray dye is rendered gray, leaving only the xray dye to be seen. Subtraction angiography requires that there be no movement between the picture subtracted and the picture with the xray dye. if there is, everything gets distorted. Webs, septae and abnormal valves may be hidden from view or false webs septae and abnormal valves may be created. There is lots of "misregistration" present on your images.
Finally, we only see the part of the vein closest to the superior vena cava. Why? does this mean that there is an obstruction at that point, i.e. a candywrapper stenosis? or does it mean something else.
I have found in many situations that how the azygous vein looks depends to a very great deal on whether the images were created in deep inspiration or end expiration. One view may look completely obstructed and the other might look totally normal. This is one of the reasons that i think that IVUS is really essential. It differentiates phasic narrowing from a stenosis extremely well.
there are other challenges in looking at the azygous that i would need to write for lot longer to explain. Then what would i write later on
Thus imaging the azygous is highly dependent upon the operator.
i do not think i can interpret your images with any reliability. Unlike nunzio's which is very clear.