I'll just add that I had dye injected before surgery, but it had nothing to do with the tumor site since I was having a complete mastectomy. The surgeon who was to perform a lympho-venous bypass wanted to trace and identify lymph channels before he removed all the nodes. I had two complete levels of lymph nodes removed since that is Standard of Care for IBC. I have been really pissed about that lymph node dissection since no cancer was found in any of them, but it left me with lymphedema in my right arm. Of course, they have no way of knowing where cancer cells are lurking until they perform the surgical tissue pathology, so better safe than sorry.
They are not worth it because a cancer diagnosis can't be made from a thermal image. There would need to be followup tests, probably including a 3-d mammogram with tomo.
Oh Nancy they kept trying real hard to find some bad news for you. The only time I was asked to "sign" off on something I did not want, was when I stopped doing dental xrays...