<]/Prev 475122/XRefStm 2576>> The main magnetic field of an MR imaging unit places unique constraints on how emergencies are handled inside an MR imaging suite, in particular within zone IV. U.S. Food and Drug Administration (FDA) guidelines refer to a magnetic field of 5 G (0.0005 T) as the upper limit where the field strength is of no potential concern for the general public, including persons with implanted electronic devices (4). However, the pediatric patient is more vulnerable to anxiety, and younger patients may not have sufficient language skills to follow commands to minimize image motion artifacts; these issues pose additional technical and safety concerns. The largest gradients occur well away from the isocenter and in some cases may be near the ends of the magnet bore. Nephrogenic systemic fibrosis: suspected causative role of gadodiamide used for contrast-enhanced magnetic resonance imaging, Gadolinium-enhanced MR imaging and nephrogenic systemic fibrosis: retrospective study of a renal replacement therapy cohort, A case of delayed onset nephrogenic systemic fibrosis after gadolinium based contrast injection, Nephrogenic systemic fibrosis: a report of 29 cases, Risk of nephrogenic systemic fibrosis: evaluation of gadolinium chelate contrast agents at four American universities, Dermal inorganic gadolinium concentrations: evidence for in vivo transmetallation and long-term persistence in nephrogenic systemic fibrosis. The American College of Radiology has defined four safety zones within MRI facilities. Patients at the highest risk for a reaction to GBCAs are those with a history of reactions to the same agent and those who have experienced multiple other allergic reactions. It is in Zone II that the answers to MR screening questions, patient histories, etc. 0000003968 00000 n Specific examples of the latter include physicians, nurses, and nonimaging technologists who enter the MR imaging suite in urgent situations; security and cleaning personnel who are responding to emergencies or are unaware of MR imaging safety hazards; and patients’ family members and friends. Any metallic or (active) electronic medical device has the potential to cause harm within an MR imaging environment. Although most fragments do not pose any translational or rotational hazard, proximity to nearby vital structures may preclude imaging (15–17). After completing both the "safety questionnaire" and the "MRI Safety quiz", save the document. For example, Publication F2182 details the method for measuring radiofrequency-induced heating of devices. 46, No. The MR imaging magnet is essentially a large coil of wire wound around the axis of the bore. Each of the components of the MR imaging unit can be a factor in injuries to patients and personnel. No adverse outcomes to fetuses have been reported after a review of studies in pregnant patients who received GBCAs, although the sample sizes of these studies were small (60). When a magnetic object is placed in the field of an MR imaging unit, it is subject to translational force and/or torque. However, the FDA also places specific limits on certain patient exposures within the MR imaging environment, including maximum field strength, noise, and radiofrequency power deposition in the patient’s body. Also recommended is that caution be used in administering GBCAs to neonates and infants because of their potentially low glomerular filtration rates and renal immaturity. In 2013, the ACR Blue Ribbon Panel on MR Safety issued an updated guidance document on MR imaging safe practices (5). For imaging purposes, the magnetic field strength must be uniform across the imaging field of view (typically 30–60 cm); hence, the most common systems are cylindric. At our institution, we incorporate the Choyke questionnaire, which enables screening for all of the risk factors listed above (except age >60 years), as well as for a history of proteinuria and a history of gout (51,52). 5� i�h[Km�b D taU�B[�������-kA��h�Ƀ\�����#����$�p�D#�1���@K@�k���"�q9��S���Rv���gÙ���㒮�O��F����i�,3;'C�tVU���UjM���;���h�Zl:}���T�JV�rU�U�z���( �V�����qrRJ�](tT��8��oA������ ��8��ho�� • Zone III – This is any area (beyond the MRI scanner room) where there is a potential magnetic field danger to persons, or any area from which there is access to the MRI scanner room. The strong main magnetic field of MR imaging units and the fact that the magnetic field is always on creates important safety issues in and near the MR imaging environment. Since the static magnetic field extends in three dimensions, some zones may extend into other areas or floors of 0000017811 00000 n Gradient or radiofrequency coils provide the source of the fluctuating magnetic fields, but the current can be produced within any conducting material, either internal or external to the body. Each MR imaging site must also have a diagnostic medical physicist or MR imaging scientist to evaluate the performance of the MR imaging unit and receiver coils and to document that each unit meets the requirements for imaging performance set by the Joint Commission, the ACR, or other regulatory body. Most MR imaging units can provide an estimate of SAR by using the total radiofrequency power that is transmitted per unit time with the patient’s weight and data on the transmit coil coverage to compute the global average SAR. 0000201699 00000 n Here we review key aspects of MR imaging contrast agent safety and give examples from our practice. The FDA sets a maximum of 140 dB for an MR imaging system and a maximum of 99 dB for a patient with hearing protection (35). Screening is a time-consuming process, and thus it is prudent to have everyone who enters zones III and IV on a regular basis trained to be level 1 or level 2 personnel as is appropriate to their roles. Skin contact against radiofrequency transmit and receive coils and cables can result in direct burns. Level 2 personnel should include all radiologists who enter into zones III and IV on a regular basis, including radiology residents and fellows. If you mark more than one box it will be deemed an incorrect answer. Access is progressive—for example, a person with zone III access automatically has access to zones I and II. In one case, a gun that was unintentionally brought into the imaging suite was pulled into the bore, discharging a round despite having its safety engaged (20). Temporary hearing loss has been documented in patients who underwent routine MR imaging examinations without protective devices (37). Other emergency equipment within the MR imaging room, such as fire extinguishers, also needs to be MR safe or MR conditional. The MRI Safety Guideline is intended to assist The Royal Australian and New Zealand College of Radiologists® (RANZCR) its staff, Fellows, members and other individuals involved in the Magnetic Resonance imaging team (radiographers, technologists and scientists) in addressing MRI safety issues and requirements. Also, many cases require the use of sedation or general anesthesia to ensure that images of diagnostic quality are obtained. To alleviate patient anxiety, family members may be allowed to accompany patients during examinations, but they must undergo the same complete MR imaging safety screening process. Publicly accessible zone I is freely accessible to the screening profile do for adults this! 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