I've had two. One was about ten years ago when I was suffering some severe dizzy spells and double vision. The results were inconclusive. On the one hand, I did have a lesion on my temporal lobe, which could mean MS. However, it was an old lesion and it wouldn't account for my symptoms. In time, the symptoms went away and I haven't had a problem since. You have to have at least two attacks in order to be diagnosed with MS, so I never have been. My wife has MS, btw. She was diagnosed about a year before my attack (it's not contagious). She's on medication (has to give herself an injection daily) and is largely symptom free.
The second MRI I had was about three years ago. I was hit in the head by an automatic garage door (fortunately, it was opening rather than closing). They didn't find any internal bleeding, but apparently I have a deviated septum AND a bone spur in my sinus cavity.
Anyways, I've never found MRIs to be too horrible. I just close my eyes and wait.