How MRI works
MRI affects the nuclei of hydrogen atoms in the body. The nuclei are made to absorb and then re-emit energy by a combination of strong magnetic fields and radio wave pulses. The emitted signals are then used to map concentrations of hydrogen in the body.
Items such as jewelry, watches, coins, keys, and credit cards must be removed before beginning an MRI. Research in the library or on the Internet why these items interfere with the procedure or pose a risk to the patient.