Good questions! Mri tube diameter varies, I think that the largest is 26 inches. Both ends are open and on some tubes the ends are "flared" to give better visability. The bigger you are, the tighter the fit. The body part of interest needs to be in the center of the tube. So if you are tall and it's your knee, your head will be outside. Most places have mirrored glassses so you can see out. Provided that it's not your head or neck that's getting scanned. Some places have music available. Metal in the body, as long as it's in bone or teeth is OK. Stuff like metal fragments in the eye are a BIG no-no. The magnent is strong enough to remove them. The other biggies are, heart pacemaker, brain clips and inner ear prothesis. Coins left in the pocket can heat up and leave a red mark. Watches, cell phones, pagers etc don't do very well either. A word about "open" MRI. An open MRI is 2 slabs with the patient in between them. If you can turn your head, you can see out. Great! but if it's a head or neck MRI you get to look straight up at the slab in front of you. So "open" can be a little missleading, also quality of the scan is normally not as good as with the tube. The newest open MRI allows you to sit or stand and see out, even watch tv or a movie(provided you stay still) There are a LOT of claustraphobic people and we can give them some oral valium for relaxation as long as they bring a driver. The valium works for people that are just nervous as well. I should mention that in order to shield the magnent there are no windows, and that patient can hear and talk to the Tech during the exam. Any time any one has a CT scan, MRI or injection in x-ray it's a good idea to call and ask questions. Most MD's do a poor job explaining the procedure. They may have ordered 100's of the test, but they may never have actually seen one. I'm at work, so I'm being brief.

Dave