MS cannot be diagnosed by MRI alone. The revised (2010) McDonald Criteria sets out the formula, if you will, for diagnosing this disease. Further, MS is a diagnosis of exclusion, meaning that its many mimics (eg Lyme disease, Lupus, Myasthenia Gravis, Sjogren's Syndrome, B12 deficiency, etc etc etc) for which there are more conclusive tests, must be ruled out.
Wiki has a good overview of the McDonald Criteria.
I'm curious as to what led to you having CT and MRI scans? Were you having neurological symptoms?
I may be wrong but from my reading of the new McDonalds criteria I'm pretty sure that for vanilla MS it can infact be diagnosed now based on the MRI finding of two of more objective lesions - one old, one new.
But to the question 'do I have MS?' Well we'd have to refer you to your neuro. My MRI report said that I satisfied the criteria for MS and my neuro confirmed this by offical diagnosis when I saw him.
I started having tremors, off and on, about a year ago. But most recently I had a sudden severe headache, a "dumb" feeling, unsteady gait and right sided tingling.