Hazards and associated recommendations for Canadian MR imaging sites.

The recent national survey reported here indicates that the use of magnetic resonance (MR) imaging in Canada for medical diagnosis may rapidly become widespread. However, the technique involves a number of potential hazards to patients, operating staff and the general public. MR involves exposure to magnetic and radiofrequency fields which may have biological effects, indicating a need for guidelines on acceptable limits of exposure for both patients and operating personnel. Other hazards include effects on cardiac pacemaker function, effects on other medical equipment important for patient management, dislodgement of metallic surgical clips, induced heating of tissue or metallic implants, danger of ferromagnetic objects becoming projectiles and a risk of asphyxiation if a superconducting magnet quenches. The recommendations in the report are practical guidelines to minimize these risks and hazards.