http://www.appliedradiology.com RSS Feed on Applied Radiologyhttp://www.appliedradiology.com//Issues/2002/12/Supplements/Magnetic-resonance-imaging-bioeffects-and-safety--A-review.aspxMagnetic resonance (MR) imaging has advanced at an astonishing speed since its inception in the early 1970s. Although the overwhelming majority of examinations are safe and uneventful, injuries and rare fatalities continue to occur. It is important to recognize and understand that there are three distinct fields inherent in MR imaging to be evaluated for bioeffects and potential safety issues: the static magnetic field, the radiofrequency electromagnetic field, and the time-varying gradient magnetic field. The static magnetic field has no known upper limit for safe exposure, although increasing use of high-field imaging spotlights the need for continued research. The radiofrequency electromagnetic field is limited by induced currents in electrically conductive material and can lead to burns. The time-varying gradient magnetic field can cause nerve and muscle tissue stimulation by induction of electric fields. Effective screening includes both written questionnaires and verbal interviews. Intensive screening of biomedical implants and devices as well as for foreign metallic objects is a critical part of MR imaging safety.Tuesday, 04 Mar 2003 15:40:28 GMT