They require dedicated cooling systems to counteract the heat induced by the large and changing currents. labeled zones—with progressive restriction of entry and increased supervision for higher zones—is a mandatory and key aspect in avoidance of MR imaging–related accidents. When an electric current is applied to this wire, a magnetic field is produced. There is only one correct answer for each question on the "MRI Safety Quiz". 0000069194 00000 n %PDF-1.4 %���� 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. 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. Delaying a nonemergent MR imaging examination in this case would bypass any potential safety issues and could eliminate imaging artifacts. 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�� The four zones are defined as follows: Zone I.—Access in this zone is unrestricted and includes all areas that are freely accessible to the general public; this is the area through which patients and others access the controlled MR imaging environment. The electric fields increase approximately linearly with the main magnetic field strength. At our institution, we are more conservative and require all level 1 personnel in zone IV to be under the direct observation of level 2 personnel. ■ List the different MR imaging safety zones and describe their restrictions. are typically obtained. However, the transmit radiofrequency coils, which, as discussed previously, can deposit very high power, can induce huge currents through the receive coil because both operate at the same resonant frequency. trailer However, the massive release of energy from a quench is unstable, and such pipes have failed. Standard testing methods for MR imaging equipment and device compatibility are provided by ASTM International, formerly the American Society for Testing and Materials, under Committee F04 on Medical and Surgical Materials and Devices. ACR Magnetic Resonance Safe Practice Guidelines: A. MR imaging safety risks are unique and require a thorough knowledge of MR imaging hardware, electromagnetic principles, and contrast agents to recognize potential sources of injury. After completing this journal-based SA-CME activity, participants will be able to: ■ Describe the major components of an MR imaging system as they relate to MR imaging safety guidelines. U.S. MR imaging centers are subject to quality and safety standards through two major mechanisms: requirements set by the U.S. FDA, which govern patient exposure limits and contrast agent regulation, and agency accreditations from the American College of Radiology (ACR) and the Joint Commission, which are now required for Medicare reimbursement. Shutting a magnet down safely requires a similar degree of technical effort. ACR guidance document on MR safe practices: 2013, Standards and publications, Standardized MR terminology and reporting of implants and devices as recommended by the American College of Radiology Subcommittee on MR Safety, MR labeling information for implants and devices: explanation of terminology, Web site, Reference manual for magnetic resonance safety, implants, and devices: 2015 edition, MR imaging of patients with intracranial aneurysm clips, MR imaging in patients with intracranial aneurysm clips, Safety of magnetic resonance imaging in patients with cardiovascular devices: an American Heart Association scientific statement from the Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology, and the Council on Cardiovascular Radiology and Intervention— endorsed by the American College of Cardiology Foundation, the North American Society for Cardiac Imaging, and the Society for Cardiovascular Magnetic Resonance, Metallic ballistic fragments: MR imaging safety and artifacts, MRI issues for ballistic objects: information obtained at 1.5-, 3-, and 7-Tesla, Projectile cylinder accidents resulting from the presence of ferromagnetic nitrous oxide or oxygen tanks in the MR suite, Preventable deaths and injuries during magnetic resonance imaging, Spontaneous discharge of a firearm in an MR imaging environment, Detection of implants and other objects using a ferromagnetic detection system: implications for patient screening before MRI, Local specific absorption rate in high-pass birdcage and transverse electromagnetic body coils for multiple human body models in clinical landmark positions at 3 T, A review of thermal MR injuries, Don’t get burnt by the MRI: transdermal patches can be a hazard to patients, Invisible metallic microfiber in clothing presents unrecognized MRI risk for cutaneous burn, MR imaging-related electrical thermal injury complicated by acute carpal tunnel and compartment syndrome: case report, Tattoo-induced skin burn during MR imaging, First-degree burns on MRI due to nonferrous tattoos, Magnetic resonance imaging and permanent cosmetics (tattoos): survey of complications and adverse events, Unusual burns of the lower extremities caused by a closed conducting loop in a patient at MR imaging, Thermal injuries associated with MRI, Safety of magnetic resonance imaging in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices, Cardiac MRI of patients with implanted electrical cardiac devices, Canadian Heart Rhythm Society and Canadian Association of Radiologists consensus statement on magnetic resonance imaging with cardiac implantable electronic devices, Sensorineural hearing loss after magnetic resonance imaging, Determination of gradient magnetic field-induced acoustic noise associated with the use of echo planar and three-dimensional, fast spin echo techniques, Potential hearing loss resulting from MR imaging, Acoustic noise reduction in MRI using Silent Scan: an initial experience, Safe use of contrast media: what the radiologist needs to know, ACR Committee on Drugs and Contrast Media, ACR Manual on Contrast Media: Version 9, Scleromyxoedema-like cutaneous diseases in renal-dialysis patients, Nephrogenic systemic fibrosis, Nephrogenic systemic fibrosis: risk factors and incidence estimation. 11, Archives of Plastic Surgery, Vol. 0000135724 00000 n Figure 2b. 0000007735 00000 n Other emergency equipment within the MR imaging room, such as fire extinguishers, also needs to be MR safe or MR conditional. Level 1 and level 2 personnel should be clearly informed that if they have any device implanted, undergo surgery from which ferromagnetic material remains in their body, or experience a metal injury, they must update their screening form immediately. Skin contact against radiofrequency transmit and receive coils and cables can result in direct burns. Resuscitation equipment, including the crash cart, should be verified and labeled as MR safe or MR conditional and sited in close proximity, either within zone II or zone III (5). 826 0 obj <> endobj After completing both the "safety questionnaire" and the "MRI Safety quiz", save the document. 900 0 obj <>stream Zone II may be used to greet patients, obtain patient histories, discuss medical insurance questions, and screen patients for MR imaging safety issues. This guide was intended for a broad audience, including MR physicists, supervisors, and hospital safety officers, and thus provides additional detail beyond what is expected for the typical practicing radiologist. Although patients and MR imaging personnel are the focus of many safety policies, greater hazards may be associated with individuals who are not patients and who do not regularly work in the MR imaging environment, as they may be more likely to unknowingly bring ferromagnetic materials into the MR imaging environment or accidentally bypass screening checkpoints (5). However, other devices require more caution. 16, No. 0000193990 00000 n Other devices have specific components that make them MR conditional or MR unsafe. Gadolinium: a specific trigger for the development of nephrogenic fibrosing dermopathy and nephrogenic systemic fibrosis? The 5-G line is marked in yellow for each magnet. During the examination, the patient moved his leg for comfort and inadvertently pinned the radiofrequency coil cable between his bare calf and the magnet bore. Modern clinical MR imaging field strengths range from 1.0 to 3.0 T, with field strengths for research systems of up to 9.4 T. These fields are approximately 10,000–100,000 times the magnitude of the earth’s surface magnetic field and more than 100 times stronger than the field at the surface of a refrigerator magnet. Don't believe it? Once the main magnetic field is established, it is left on and can remain stable at several hundred amperes for years, as long as the liquid helium level in the cryostat is sufficient to maintain the coil in a superconducting state. 0000002774 00000 n The American College of Radiology has defined four safety zones within MRI facilities. 0000004678 00000 n The use of gadolinium-based contrast agents (GBCAs) in MR imaging is well established. 0000004792 00000 n Gradient coils are fixed in place relative to the main magnetic field coils and are typically installed within the magnet bore. Deaths can occur owing to respiratory failure and limited mobility (41–43). Although no adverse effects to the fetus or neonate have been established, intravenously administered GBCAs are known to enter fetal circulation and to persist within the amniotic fluid. All MR imaging facilities should have a documented plan to handle emergencies within zone IV, including cardiac arrest or code, magnet quench, and fires. It is especially critical that all potential emergency responders are aware of the hazards associated with zone IV, as it is easy to forget to properly screen for potential ferromagnetic projectiles during an emergency response. startxref 0000228857 00000 n Unlike the main magnetic field, gradient coils are subject to rapidly changing currents, which are necessary to provide encoding within the time constraints of pulse sequences. Connect with us . It would be ideal for an emergency plan to require that one of the MR imaging personnel remains at the entrance to zone IV specifically to ensure that first responders enter the area only if necessary and that they do so safely. Minimizing these risks, however, also requires application of this knowledge in a practical and effective manner. This article provides an overview of MR imaging safety that is geared toward the practicing radiologist. 0000009926 00000 n In our practice, Zone I includes the entrance to the registration area of outpatient MRI facilities. The door itself, which is designed for radiofrequency shielding and is typically heavy, can also become a hazard if it swings open or shut from the sudden pressure gradient across its frame. If the patient’s eGFR is 30–45 mL/min/1.73 m2 and has decreased by 10 mL/min/1.73 m2 or is 15–29 mL/min/1.73 m2 and remains stable, we administer a Group III GBCA. 33, No. MRI SAFETY ACR White Paper on Safety (Published in June 2002, updated in 2004, 07,10,12, 2013) ... MRI safety Zones III and IV Non MRI personnel wishing to enter these zones must be screened and accompanied by a level two MR person All patients must wear a gown device and object screening Objects are to be identified as: MR safe MR conditional MR unsafe. After training and safety screening are performed, level 1 personnel can have unrestricted access to zones III and IV on an annual basis. The majority of MR imaging–related burns occurred during routine examinations that involved typical pulse sequences. ACR Safe Practice Guidelines B. Static Magnetic Field Issues: Site Access Restriction MR personnel and non-MR personnel There are two levels of MR personnel Level 1: Those who have passed minimal safety educational efforts to ensure their own safety as they work within Zone III. The ACR Manual on MR Safety addresses numerous MR safety-related topics such as: Patients with NSF have acute and/or severe chronic kidney insufficiency (estimated glomerular filtration rate [eGFR], <30 mL/min/1.73 m2), and, with few exceptions, are known to have received a GBCA (44,45). John Posh R.T.(R)(MR), Metrasens’ Director of Education, MRI Safety Officer. Reports of NSF in the pediatric patient population are rare (57). Large transmit coils (eg, the body coil built into the bore) are capable of transmitting tens of kilowatts of radiofrequency power in short bursts. 0000017811 00000 n 0000135076 00000 n What are the ACR Safety Zones? The sudden large volume of helium gas can act as an asphyxiant, and the fog created from the low-temperature gas can eliminate visibility. 4, Anaesthesia and Intensive Care, Vol. 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. Once the current eGFR is established as described, if the eGFR is 30 mL/min/1.73 m2 or greater and has not decreased by 10 mL/min/1.73 m2 within the past 6 months or from baseline, we administer a GBCA from either Group II (gadobenate dimeglumine, gadoteridol, or gadobutrol at our institution) or Group III (gadofosveset or gadoxetate disodium). For subsequent GBCA administration for MR imaging, we recommend waiting at least 10 hours for patients with a stable eGFR of 60 mL/min/1.73 m2 or greater, at least 48 hours for patients with a stable eGFR of 30–59 mL/min/1.73 m2, and at least 96 hours for patients with a stable eGFR of 15–29 mL/min/1.73 m2. Magnetic resonance (MR) imaging can provide critical diagnostic and anatomic information while avoiding the use of ionizing radiation, but it has a unique set of safety risks associated with its reliance on large static and changing magnetic fields, high-powered radiofrequency coil systems, and exogenous contrast agents. Wires and leads—for example, electrocardiography cables or jewelry (eg, piercings)—can form an inductive circuit if they are accidentally coiled. Any metallic or (active) electronic medical device has the potential to cause harm within an MR imaging environment. Therefore, the majority of MR imaging magnets use superconducting wire, which has essentially zero electrical resistance provided that it is maintained at a very low temperature. For example, programmable ventriculoperitoneal shunts may contain metallic or even magnetic parts that are used to adjust valve pressure settings in vivo, resulting in MR-conditional requirements. For all inpatients, we calculate an eGFR within 24 hours if an MR imaging examination with a GBCA is desired and apply the same rules described previously. 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). Enter your email address below and we will send you your username, If the address matches an existing account you will receive an email with instructions to retrieve your username. Other than best practice documents, regulatory structures, and MR system documentation, the ABMRS does not endorse any third party materials for exam preparation 12 “Together with MR Site accreditation, the formation of the ABMRS now completes the logical extension of … The majority of MR imaging unit noise originates from gradient coils because they are subject to rapid changes in current, which in turn interact with the main magnetic field through Lorentz forces. 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. your own Pins on Pinterest Arrow = approximate contact point. If a patch is kept on the patient, special care must be taken to ensure that the patch is not too close to a coil, a cable, or the magnet bore. Continuous computation is used to ensure that the SAR is within FDA limits. All MR imaging facili- ties should have a documented plan to handle emergencies within zone IV, including cardiac arrest or code, magnet quench, and fires. An accredited center must have a documented MR imaging safety policy tailored for its practice that is reviewed annually by a supervising MR imaging physician, covering everything from signage and access control to patient screening and mechanical safety. Objects with microscopic amounts of conductive material can produce enough heat to cause a burn. Although regulations and standards help form the backbone of MR imaging safety policies, the development of a culture of safety ultimately relies on the ability of radiologists, technologists, and administrators to tailor their policies to suit their individual facility and the needs of their patients. 0000018497 00000 n While this shuts off the magnetic field very rapidly, the rapid coil heating causes the surrounding liquid helium, typically thousands of liters, to boil off in an explosive manner. It is also vital for operators to understand the difference between the quench button and the emergency power shutoff or shutdown button, which shuts off many of the electrical systems surrounding the magnet without initiating a quench. First described in the literature in 2000 (41), NSF is a systemic fibrotic disease affecting the skin and internal organs that is similar to but distinct from scleroderma. The local power deposited in a tissue is proportional to the tissue conductivity and the square of the local electric field produced by the radiofrequency transmission system. Regulations, standards, and guidelines are being continuously updated as MR imaging becomes more widely available and newer techniques and technologies emerge. 0000054946 00000 n Level 1 MR imaging personnel are explicitly permitted to accompany non–MR imaging personnel into and throughout zone III. Unless such patches are specifically verified by the manufacturer as MR safe, they should be removed for an MR imaging examination. To minimize this risk, modern coils and cables are typically insulated and sealed within a thicker plastic protective sleeve to provide a minimum safe distance. must be carefully screened because they can become projectiles that can injure subjects and staff, and damage the MRI equipment. The ACR recommends that adult guidelines for identifying at-risk patients and for administering GBCAs be followed. The training for level 2 personnel includes the same material as for level 1 personnel, with the addition of more in-depth material on the safety screening process, the portable objects that can be brought into zone IV and the U.S. FDA labeling criteria for these, and the safety response and emergency procedures in the MR imaging environment. MRI Zone Signs are available for each of the four MR zones and are designed to comply with the OSHA standards for safety. Radiologists, technicians, and other health care providers who are pregnant are allowed to work around and in the MR imaging environment throughout all stages of their pregnancy. A layout of one of the magnet suites at our institution is provided as an example of the different zones (Fig 4). A retained lead from prior temporary epicardial pacing is one such example; no additional screening is required for these patients (32). • Patient safety — Previous ACR guidance recommended dividing the MRI suite into four safety zones, with increasing levels of magnetic exposure from Zone I (entrance to the MRI facility) up to Zone IV (generally considered the magnet room itself). Although they are allowed to position patients, image and archive, inject contrast material, place radiofrequency coils, and enter the MR imaging room in response to an emergency, it is recommended that they do not remain in the MR imaging bore or magnet room during data acquisition or imaging (5). Careful screening is required to identify these at-risk patients. Coils of different sizes and shapes are available to accommodate different anatomic areas, ranging from full-body coils to surface coils for small joints. Ballistic implants, such as shrapnel and bullets, warrant special consideration because their ferromagnetic composition may not be known and their anatomic position is variable. Figure 4. Also, many cases require the use of sedation or general anesthesia to ensure that images of diagnostic quality are obtained. In addition to a known history of renal insufficiency, other risk factors outlined by the ACR include a history of diabetes or hypertension requiring therapy, age older than 60 years, and prior renal surgery or malignancies (40). GBCAs are excreted in minimal amounts in breast milk; amounts are estimated to be less than 0.04% of the total dose (54,55). Although animal studies have demonstrated deleterious effects of MR imaging exposure on the fetus and therefore have raised concerns, these studies are not applicable to humans, and their results cannot be extrapolated. In some cases, such as when radiographs are needed to screen for implanted devices or ferromagnetic foreign bodies, complete anonymity may not be possible, but any such radiographs or workup should clearly be performed with Health Insurance Portability and Accountability Act compliance. Any physician extenders, such as nurse practitioners and physician assistants, who are employed regularly in zones III and IV should be level 2 personnel. Here we review key aspects of MR imaging contrast agent safety and give examples from our practice. 0000201699 00000 n 2, 19 May 2017 | Journal of Magnetic Resonance Imaging, Vol. The ACR considers use of MR imaging to be relatively risk free during pregnancy, and no special consideration is recommended for the first, versus any other, trimester in pregnancy (5). 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. MR Safety Reference Documents. Aneurysm clips, for example, are attached to soft-tissue structures only, and there has been one documented case of a fatality attributed to the rotation of such a clip while the patient was adjacent to the magnet; in that case, the ferromagnetic content was underestimated because the clip was incorrectly identified (12,13). 0000018384 00000 n ACR Guidance Document on MR Safe Practices: 2013, and IEC 60601-2-33), and MR system manufacturer documentation. Only MR imaging personnel shall be provided free access to zone III, and non–MR imaging personnel are not to be provided with independent access until they undergo the proper education, training, and certification to become MR imaging personnel themselves. 8/11/2014 6 ferromagnetic … A quench occurs when a portion of the superconducting coil is warmed above the superconducting threshold and ceases to be superconducting. Although these detectors are currently approved only for screening for external ferromagnetic objects, they may be used in the future for implant screening (21). Patients in zone II are not free to move at will and should be under the supervision of trained MR imaging personnel. (b) Photograph shows a phased-array coil similar to the one involved in the incident. (b) Photograph shows a phased-array coil similar to the one involved in the incident. Several types of implants may require a waiting period before an MR imaging examination can be performed. xref One of the level 2 personnel at each MR imaging site is the MR imaging medical director, whose job includes ensuring that MR imaging safe policies and procedures are established, updated, and followed by all staff members, as well as overseeing MR imaging safety issues that arise during the operation of the MR imaging site. 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