The thing about the biopsy is, if it's positive, you've hit the jackpot for treatment. But they can also come up with a false negative and often do. This is because the cells are random, and if the piece they take out for the biopsy doesn't happen to have a cell in it, it looks like you're negative for GCA. Hopefully, you'll get the straight goods with the MRI. You're lucky you have access to it.