Not an expert by any means. I have heard that 90% if the liesions show up on the brain. I believe they can show up anywhere on spine though, just not as common.
I had mri of all three parts of the spine just a few weeks ago. They did find an active liesion on my spine, the middle of the spine, I don't know what the medical term for that part of the spine is.
Let us know what you find out.