To my knowledge, all they've ever done for MRIs in my case has been brain and neck, no lower. I had a positive lumbar puncture (o-bands). My symptoms for the most part were very non-specific, except for having L'Hermittes Sign and girdle-band sensation - those 2 symptoms sealed the deal, so to speak, on it being MS.

I've since had Optic Neuritis, but considering my neuro guesses I had MS at least 5 years prior to being diagnosed in 2008, I have done pretty well as far as avoiding massive progression. Though, there is most definitely progression (some symptoms now never resolve and are permanently there - mild, moderate, or severe, depending on the day).

Long story short, hearing "you have no lesions on your spine, therefore it's not MS" is maddening. I'd get a second (or even third) opinion.