I was told that MRI scans are non invasive, and regardless of sr106s post I still believe that. I had one for a slipped disc causing severe scyatica, and the results of the scan are superb allowing the surgeon to make minimum cuts to accurately home in on the trouble spot. I had mine 9yrs ago and have not had a spot of bother since. HOWEVER, don't be like me and be the big brave boy, if offered, take vallium. I refused (lying still in a pipe for 50mins? no probs.) and I was verging on panic most off the time because you feel trapped! Even now, if my wife pulls the bedclothes tightly over my arms I can feel the panic rising. Please tke me seriously, as I had no idea it would cause me any trouble. Best of luck.