28, No. A more comprehensive article on contrast agents (39), which provides further detail on the different types of GBCAs, a detailed overview of safety-related studies, and summaries of key ACR guidelines, can be found in this monograph. 9, Journal of Magnetic Resonance Imaging, Vol. Although most fragments do not pose any translational or rotational hazard, proximity to nearby vital structures may preclude imaging (15–17). The inherent high magnetic field strength of a clinical MR imaging unit poses a risk for projectile injury or MR imaging equipment damage if a ferromagnetic object approaches too close to the magnet and is pulled into the bore. As a result, as one approaches the bore of the MR imaging magnet, the magnetic field will increase rapidly, so the subjected force on a magnetized object can be sudden and unpredictable. 0000002990 00000 n
of Radiology (ACR) White Paper on MR Safety, published in 2002 and revised in 2004 (Kanal et al., 2002, 2004) and in other recent publications (Shellock, 2001, 2006; Shellock and Crues, 2004). If you mark more than one box it will be deemed an incorrect answer. The Zones are designated as I through IV and each progressive Zone has more stringent safety requirements. 0000069466 00000 n
Reducing the read bandwidth or increasing the repetition time can reduce dB/dt. 49, No. Patients in zone II are not free to move at will and should be under the supervision of trained MR imaging personnel. During installation of the MR imaging unit, the current in the superconducting magnet is ramped up slowly to obtain the desired magnetic field strength, a process that takes several hours. 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. This information is not meant as a comprehensive reference for all aspects of MR imaging safety, and all practitioners of MR imaging should consult their respective country’s imaging regulations and their particular vendor to ensure practice safety. In addition to the obvious threat of bodily harm, projectiles can also cause extensive damage to expensive hardware and additional loss of service for required downtime during repairs. It remains the intent of the ACR that these MR safe practice guidelines will prove helpful as the field of MRI continues to evolve and mature, providing MR services that are among the most powerful, yet safest, of all diagnostic procedures to be developed in the history of modern medicine. 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). 0000228857 00000 n
Zone III, or at the very least, the area within it wherein the static magnetic field strength exceeds 5 G, should be demarcated as being potentially hazardous. 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. 0000009489 00000 n
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). The ACR has defined different levels of MR imaging personnel as follows (5): (a) level 1 MR imaging personnel—those who have passed minimal safety educational efforts to ensure their own safety as they work within zone III; (b) level 2 MR imaging personnel—those who have been more extensively trained and educated in the broader aspects of MR imaging safety issues; and (c) non–MR imaging personnel—all those not having successfully complied with MR imaging safety instruction. Delaying a nonemergent MR imaging examination in this case would bypass any potential safety issues and could eliminate imaging artifacts. In most systems the 5 Gauss field is confined within the scan room, so the fringe field does not affect any area external to the magnet room. Health care workers at outpatient facilities in particular may need to prescreen patients before their appointment to minimize this potential delay at the time of MR imaging. Thermal injury from MR imaging is uncommon, with 419 reported cases between 2000 and 2010 in the United States (23). A sample screening form from our institution is included in Figure E1 (online); the ACR guidelines also provide a generic version (5). 25, No. 0000000016 00000 n
10, No. your own Pins on Pinterest Therefore, the amount transferred to a nursing infant would be at least 100 times less than the permitted dose of 200 µmol/kg of body weight for neonates (54). MR imaging may be indicated in patients who are unable to provide answers to the screening profile. 8. These are usually receive coils that do not produce radiofrequency power themselves. Magnet rooms are generally equipped with a quench pipe that is intended to vent this boil-off safely out of the building. MR-conditional intracardiac pacemakers contain electronic filters that nearly eliminate the possibility of the antenna effect. 33, No. To avoid this possibility, many institutions, including our own, require all patients to change into hospital gowns for their MR imaging examination. 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. MR imaging units make use of applied magnetic field gradients to spatially encode the MR imaging signal. This zone should be clearly marked (with a red light and a sign stating that the magnet is always on) as potentially hazardous because of the strong magnetic field (Fig 3). Severe anaphylactoid reactions, while extremely rare, do occur, and the ACR recommends that patients with previous reactions be injected with a different contrast agent if one is needed for subsequent MR imaging and that at-risk patients be premedicated with corticosteroids and antihistamines. ACR Magnetic Resonance Safe Practice Guidelines: A. MR Safety Reference Documents. At our institution, we use a computer-based education module that has a combination of slides and a video, but printed handouts or lectures could also be used. At present, although results of only a few studies with small numbers of patients, variable data, and confounding factors are available, there is no definitive evidence of harmful effects from performing routine (nonenhanced) MR imaging examinations in pregnant patients. 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. With the main magnetic field strength changing magnetic fields and the strictly controlled zones and! Than 5 Gauss are inconsequential to MRI safety Quiz '', save the document technique termed.... 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