Safety Alert for Magnetic Resonance Imaging System

Safety alert

395

2002-02-15

Brazil

ANVISA

http://www.anvisa.gov.br/sistec/alerta/consultaralerta.asp

The clinical scientific literature and the databases of technovigilance contain numerous reports of injuries in magnetic resonance centers (mri) and some reports of deaths. ecri states that most of the incidents are caused by interactions of the electromagnetic fields of magnetic resonance systems and other equipment in or brought into the mr environment, and that these incidents can be attributed to one of the following phenomena: forces static magnetic field, radio frequency heating, image artifacts and malfunctions. because of the existence of a static magnetic field of the mr system, iron and other magnetic materials are subject to two different forces: torque and translational force. ecri suggests that for magnetic and magnetic iron implants, torque can lead to compression or torsion of the tissues underlying the implant, which may cause rupture of the blood vessels and may cause changes in the orientation of the magnetic particles implanted in the patient. translational forces can cause magnetic or other ferromagnetic objects that are not fixed, to launch and literally fly through the air; this phenomenon is called a projectile effect. even appliances that may look safe, have become projectiles in the rm environment (eg some pillows and sandbags, which contain magnetic iron components). another potential consequence of a projectile incident is that it can cause superconductive system drop. ecri says that the radio frequency electromagnetic field of the rm system can induce currents in present, electrically conductive materials within the nucleus, bore¿ of the mr system. the induced current in counterpart can cause heating of the conductor, which can lead to burn of the patient if the conductor is in contact with the body. patients may serve as a whole or part of conductive circle, and have received burns where their toes or hands touched the thigh on the same side or on the bridge where their thighs were touched or crossed their arms. also, rare reports suggest that patients with tattoos have suffered mild localized heating burns, since tattoos may contain iron oxide or other magnetic iron substances, which are conductive. other problems that have been reported are image artifacts that may result in field disturbance, by signals sent by conductive materials in the mr environment, and by radio frequency disturbance. because they affect image quality, image artifacts can also affect the diagnostic value. finally, the static magnetic field of the rm system and its radio frequency and its magnetic gradient fields can seriously affect the operation, reliability, and accuracy of medical products that were not designed or designed appropriately for the mr environment. monitor alarm should alert rm personnel to magnetic disturbances.

ECRI recommends the following to ensure the safe use of the equipment in the RM environment: (1) designate a safety officer to ensure that the procedures are effective and consistent for the safety of the RM environment. (2) Establish and periodically review procedures and MRI routines and evaluate the level of compliance by your staff. (3) Identify areas of the RM room and adjacent areas on other floors where the magnetic force exerts an influence greater than 5G. Set this area as the RM environment and restrict access to this area. (4) Give formal training on safety considerations in the RM environment for all RM personnel and for all other personnel who may enter the RM environment. (5) Carefully inspect all persons entering the RM environment for presence of magnetic or conductive objects, inside, on or in conjunction with their bodies. (6) Check patients' medical records carefully about implants or other suspicious foreign objects. (7) If possible, only allow access to the MR environment, to patients wearing hospital gowns without traces of metallic gum. (8) Do not allow any equipment or product containing magnetic components (especially ferromagnetic) above critical level 5G unless they are labeled, safe or compatible with the RM environment. In addition, make sure that you are following the manufacturer's instructions regarding the compatibility of the products with the safety in the RM environment. (9) Keep the list of safe and compatible equipment and products in a conspicuous location, including restrictions on use. (10) Do not change safe or compatible equipment. (11) Be extremely careful if you must use equipment with ferromagnetic components in the RM environment; To prevent these equipment from moving too close to the RM system, the equipment must be properly labeled and must be at a safe distance from the RM system secured / retained by non-magnetic means. (12) If possible, use fiber optic, carbon fiber, graphite or high impedance electrodes instead of conductive or low impedance electrodes, wide-area electrocardiogram electrodes. (13) Remove all unused or unnecessary materials that are electrically conductive (eg, electrodes, sensors, cables, RF guides) from the patient and from the proximity of the cylinder. If electrically conductive conductive materials should remain in the cylinder, be sure to prevent this material from contacting the patient. (14) Give the patient a compatible, safe alarm with MRI so that it alerts the staff in case of an emergency. (15) Do not assume that objects such as sandbags or hospital pillows are safe in the RM environment without testing them. (16) At least, equips the room with safe oxygen equipment for the RM environment.