You have to be your own advocate!
I've just found this site and I wanted to comment on MRI's, and CT scans. I could go into everything that happened to me, but it's such a long story that I'll just say that at the end of last year I had an L4-L5/L5-S1 lumbar fusion with screws and rods. I had had an MRI taken due to sciatica pain about 3 months before surgery, and it did show an 8mm disc herniation, but what it didn't show was that there was scar tissue wrapped around the nerve root and the neurosurgeon had to carefully remove it during surgery. The tests beforehand didn't show that. If they had just treated me with meds and epidurals and PT, it would have damaged the nerve more than it did, and neuropathy (the famous word they use after something has squeezed the life out of the nerve) begins. There's no cure for neuropathy.
What I'm trying to suggest is that no test will show that and it's so common after previous back surgery. Since I had had two lamenectomies, one in '03 and the other in '04, and the nerve root had been impinged with disc material (herniation with nerve involvement) that I was told that it wasn't uncommon for the scar tissue to form after years. So I guess what I'm saying is that if there is pain then there is a reason and you have to be very proactive in your treatment! Thanks.