Were you ever in a car accident, have a sports injury, hit your head during a fall, been in any sport fights, or taken any blows to the face or head? These clots can occur with any head trauma. JMO
Have you had Lyme disease? Infections like that can cause these too. I see you wrote LymeNurse, your career, or do you carry that germ?
I wish you all the best with your procedure in May. I would see another doctor before the procedure, just for a second opinion. If not, make sure the treating doctor sees the MRV and report. He may not test up that high with the dye.
Did they do your Ultrasound next to your ear and head? They checked my cerebrals and sinuses with another US attachment.