Folks, that M in MRI stands for "magnetic". The machine uses a *very* strong magnet! From the website:
A supposedly ambulatory patient told a technologist that she was feeling rather tired and weak. She asked if she could sit down while the tech was entering data into the computer. So the tech let her sit in one of the console chairs. Since the woman was rather tired, the technologist pushed the patient into the room on the chair. Since this was an actively shielded magnet, she thought it would be OK. The patient got off the chair, sat on the table and gave the chair a little push with her feet. The chair rolled away and just kept right on rolling on a curved path to the magnet bore and flew right in. Fortunately, no one was hurt but it took almost a full day to ramp the magnet down, pull the chair out, ramp back up and check out the system.
More Flying Objects found in MRI Machine