Need some info for MRI

I had an accident of my knee back in 1995 when i was a 7 yrs old kid. I was running on the road and suddenly i hit the rock and i fell on the road and i remember sliding for nearly 2-3 secs which made me very injured. I didnt know at that time, but when i reached home and the pain was excruciating, i decided to take a look and found out that my knee was wide open, I could see the bone of my knee and the reddish flesh inside of my knee. It was very horrible scene. My dad rushed me to the clinic and i got 7 stitches there. Now its 2009. What if I would like to have an MRI for my head or anywhere else of the body, i sometimes think that there could be very little pieces of the rocks or stones residing in my knee since that accident. Is that possible? However i dont feel any pain in that knee. Its absolutely fantastic. Can i have MRI with the feeling i mentioned above that there could be very very small pieces (as in my imagination, which sometimes ***** ALOT), and that while scanning they could move inside of me? As MRI attracts everything that has metallic properties. I guess rocks and stones have metallic properties? Please guide me? Could they move inside of me or up to the brain?

[Paxiled]

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