I think I have to get an mri for my knee..? I have questions about what an mri is?

An MRI isn't anything bad. You're just in a small tight oval space, and it's a Magnetic Resonance Imaging. It gives a more detailed photo than the X-ray does. I've had a million on my brain because of brain damage. I have epilepsy. They slid me in head first, so you might be slid in feet first. I don't know how far it can go down the body if you're laying in head first. All of mine have been done at the U.S.C. University Hospital.