Strandness's Duplex Scanning in Vascular Disorders
By R. Eugene Zierler
The supraclavicular subclavian vein can be difficult to image, but a midrange transducer with a small footprint is ideal for visualizing this important segment. This is a common location for a venous stenosis as the subclavian vein curves to join with the internal jugular vein and becomes the innominate vein (see Fig. 18.4). There is often a valve in this segment that can contribute to a stenosis if the valve leaflets become fibrotic over time.
Look at that, it's in the textbook.
This is from 2009, fourth edition, so it predates the CCSVI controversy.