Hi POTS, my wife was tested for CCSVI at Stanford and the Hubbard Foundation in San Diego. Those facilities both use a functional 3T MRI/MRV/MRA to image the anatomy of your vessels (with particular focus on internal jugulars and azygos), but also test the flow of blood through those vessels as well. Stanford, and others, also perform an ultrasound of the neck area, not transcranial. There are some facilities that use only MRI or only ultrasound. I am not aware of any that use CT, but I haven’t looked everywhere.