<unk>  is, in general, a safe technique, although injuries may occur as a result of failed safety procedures or human error. Contraindications to<unk>  include most cochlear implants and cardiac pacemakers, shrapnel, and metallic foreign bodies in the eyes.<unk>  in pregnancy appears to be safe, at least during the second and third trimesters if done without contrast agents. Since<unk>  does not use any ionizing radiation, its use is generally favored in preference to CT when either modality could yield the same information. Some patients experience claustrophobia and may require sedation or shorter<unk>  protocols. Amplitude and rapid switching of gradient coils during image acquisition may cause peripheral nerve stimulation.<unk>  uses powerful magnets and can therefore cause magnetic materials to move at great speeds, posing a projectile risk, and may cause fatal accidents. However, as millions of<unk> s are performed globally each year, fatalities are extremely rare. Overuse Medical societies issue guidelines for when physicians should use<unk>  on patients and recommend against overuse.<unk>  can detect health problems or confirm a diagnosis, but medical societies often recommend that<unk>  not be the first procedure for creating a plan to diagnose or manage a patient's complaint. A common case is to use<unk>  to seek a cause of low back pain; the American College of Physicians, for example, recommends against this procedure as unlikely to result in a positive outcome for the patient.
Magnetic resonance imaging
Magnetic field imaging
Magnetic Resonance in Medicine
Electron resonance imaging
Radiography
Autoradiograph
Functional imaging
Myelography