Pennsylvania Patient Safety Advisory Safety in the MR Environment: Ferromagnetic Projectile Objects in the MRI Scanner Room ABSTRACT been shown to travel at speeds up to 40 mph into a The static magnetic field of a magnetic resonance 1.5 T magnet.1 imaging (MRI) scanner exerts forces on ferromagnetic and other magnetic materials near the field. These Some incidents of the projectile effect have been forces can draw unrestrained objects, making them reported in the mainstream news media. For example, airborne, into the scanner’s magnet bore. This phe- one fatal event involved a six-year-old child undergo- nomenon is known as the projectile effect and can ing an MRI scan. During the scan, while the child was result in catastrophic consequences for individuals lying on the MRI table, an oxygen canister consisting near the scanner and significant damage to equip- of ferromagnetic materials was brought into the room. ment. To avoid serious or fatal injury from projectiles, The force of the magnet pulled the oxygen canister magnetic resonance (MR) personnel must understand into the magnetic bore, causing the canister to strike the principles of the projectile effect and properly the child’s head. The child eventually died from the screen individuals before entering the scanner room injuries.2 for ferromagnetic objects. In some cases, medical In another well-known event, an off-duty police offi- equipment needed in the scanner room for patient cer was scheduled to undergo a MRI examination. assessment or treatment (e.g., physiologic monitor, A misunderstanding occurred between the officer infusion pump) could also pose projectile risks. Addi- and the magnetic resonance (MR) technologist when tionally, the static magnetic field may cause medical the technologist asked the officer to proceed to the equipment to malfunction, which may result in serious MRI patient waiting area. The officer mentioned his or fatal patient injury. MR personnel must know what holstered handgun to the technologist before entering equipment is safe to allow into the scanner room and the MRI dressing room. The technologist informed what equipment is unsafe and should be left out of the officer to proceed to the patient waiting area the room. Between June 2004 and December 2008, with the gun; the technologist planned to secure the the Pennsylvania Patient Safety Authority received weapon in that room. However, the officer misun- 27 reports of objects becoming projectiles in the derstood and brought the gun into the MRI scanner MR environment, 16 ferromagnetic items that were room. While the technologist was entering the offi- brought into the MRI scanner room without becoming cer’s patient information into a computer, the officer projectiles, and 5 ferromagnetic items almost allowed entered the scanner room and attempted to place the into the MRI scanner room. Proper MR screening gun on top of a cabinet, which was approximately practices for ferromagnetic items and establishing 3 feet away from magnet bore. The force of the mag- protocols for identifying and labeling equipment that net pulled the gun from the officer’s hand and drew can and cannot be brought into the scanner room will the gun to the magnet bore. When the gun struck the help reduce the risk of objects becoming projectiles magnet, it spontaneously discharged a bullet (despite within the MR environment. (Pa Patient Saf Advis 2009 that fact that the firearm’s safety mechanism was Jun;6[2]:56-62.) engaged), which struck a wall in the scanner room. There were no injuries as a result of this incident.3 Between June 2004 and December 2008, the Penn- Editor’s Note sylvania Patient Safety Authority received 44 reports describing 27 ferromagnetic items that became projec- A March 2009 Pennsylvania Patient Safety Advisory article tiles, 16 ferromagnetic items that were brought into discussed magnetic resonance (MR) safety screening practices. This the MRI scanner room without becoming projectiles, article continues the discussion of MR safety, focusing on the safety and 5 ferromagnetic items that were almost brought concerns of ferromagnetic objects and ferromagnetic medical equip- into the MRI scanner room. (Forty-eight items ment entering the magnetic resonance imaging scanner room. were cited in 44 reports: in 2 projectile reports, an Ferromagnetic materials can be influenced by trans- oxygen tank and a ventilator were reported; and in lational (linear) and torque (rotational) forces exerted 2 other reports, an oxygen tank and a stretcher were by the static magnetic field of the magnetic resonance reported.) Of the 44 reports, only 3 minor injuries were reported. See Tables 1 through 3 for information imaging (MRI) scanner. These forces, primarily about the ferromagnetic items cited in the reports. translational forces, can draw unrestrained objects, making them airborne, into the magnet’s bore. This For illustration, the following are examples of the hazardous phenomenon is known as the projectile, or narratives of Serious Events and Incidents involving missile, effect, which can potentially result in serious projectiles reported to the Authority. or fatal injuries to individuals in the scanner room. After completion of the MRI study, the technician Any object, regardless of size, can become a dangerous proceeded to place the patient’s wheelchair at the projectile. For example, paper clips and hairpins have door threshold of the MRI room. When she leaned Page 56 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Vol. 6, No. 2—June 2009 Pennsylvania Patient Safety Advisory Table 1. Projectile Ferromagnetic Items Table 2. Nonprojectile Ferromagnetic in MRI Scanner Rooms Reported to the Items in MRI Scanner Rooms Reported to Pennsylvania Patient Safety Authority, the Pennsylvania Patient Safety Authority, June 2004 through December 2008 June 2004 through December 2008 FERROMAGNETIC ITEMS QUANTITY OF ITEMS QUANTITY OF Cardiac monitor 1 FERROMAGNETIC ITEMS ITEMS Clipboard 1 Cardiac monitor 3 Hearing aid battery 1 Cardiac monitor/recorder 1 (long-term) Infusion pump 1 Cell phone 1 Intravenous (IV) basket 1 Face mask with metal nose strip 1 IV pole 1 Hairpin 5 Knife 2 Infusion pump 2 Laryngoscope 1 Insulin pump 2 Monitor (type unknown) 1 Telemetry transceiver 1 Nail clippers 1 Total 16 Oxygen tank 2* Ring (jewelry) 1 Sandbag 2 Scissors 2 respiratory technician acknowledged to the two MRI Step stool 2 technicians that the oxygen tank could not go into the MRI room. The respiratory technician asked for the Stethoscope 1 MRI-compatible ventilator stand for the ventilator Stretcher 1 (the patient was bagged at the time). The respiratory Telemetry transceiver 1 technician took the ventilator that had two oxygen Ventilator 1* tanks into the MRI room. [The technician] realized Wheelchair 2 that the oxygen tanks were on the ventilator and Wooden chair with metal 1 went to the leave the room when the magnet took the strip in seat cushion tanks and the ventilator into the MRI. The patient Total 27 was outside the MRI while this occurred. * One oxygen tank and one ventilator were recorded on the same report submitted to the Authority. A [brand omitted] [syringe] pump used in the nursery accompanied a patient to MRI. A label on the pump stated that it was MR-compatible and upon initial over the wheelchair to lock the wheels, the wheelchair review it appeared to be safe. The pump was taken was attracted to the MRI and rolled into the equip- into the MRI suite with the patient, and the patient ment. There was no injury to the patient or staff. was positioned on the table. The pump was placed The MRI equipment suffered slight damage to the at the end of the table. As the table advanced in the cover. bore of the magnet, the pump flew to the front of the magnet, sticking itself to the magnet cover. The baby A patient was brought to the MRI room. [The was not injured and the pump was removed from the patient’s] IV [intravenous line] became kinked. A magnet cover. The pump was placed at a safe dis- technician entered the room to fix the IV tubing. The tance and the examination was performed as ordered. technician forgot to take scissors out of pocket. The scissors became attached to the machine. There was The patient was placed on the MRI table and the no apparent injury. [MR] safe monitor was connected to the patient. While positioning the patient, the monitor became A post cardiac catheterization patient with a sand- attracted to the magnet, grazing the patient’s head. bag placed on right groin went to radiology for MRI. Patient was placed on the table. When the technician The patient came to the [MRI] department and began advancing the table, the magnet pulled the required anesthesia. The patient was [positioned] in sandbag from the patient’s groin onto the outer hous- the [MR] scanner when the anesthesiologist decided ing of the MRI unit.* to use the laryngoscope. [The laryngoscope] was MR The critical care patient was taken to MRI with a compatible without batteries. The handle went into nurse and respiratory technician. . . . The patient was the magnet and was retrieved without trauma to the hooked up to the MRI monitoring system and the patient or staff. The reports above illustrate the dangers of ferromag- netic items making their way into the MRI scanner * For more information about sandbags in the magnetic resonance environment, refer to the article “Sandbags May Not Be What You room. The risk of an object becoming a projectile Think” in the September 2006 issue of the Pennsylvania Patient increases the closer the object gets to the magnet bore. Safety Advisory. Individuals entering the MRI scanner room must Vol. 6, No. 2—June 2009 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Page 57 Pennsylvania Patient Safety Advisory understand that, for the vast majority of MRI systems, bore. Each MRI system will have a fringe field that is the magnet is always on and that the magnetic field is unique to the specific supplier’s model of MRI sys- always present even when no scan is being performed. tem and the scanner room in which it is located. For Precautions are necessary when bringing any item illustration purposes only (these dimensions are not into the MRI scanner room. associated with specific suppliers of MRI systems), for an unshielded 1 tesla (T) (1 T = 10,000 G) MRI sys- Additionally, visual inspection alone may be inad- tem, the 5 G line might be approximately 15 feet from equate to distinguish ferromagnetic projectile threats. the magnet bore; the 100 G line, stronger magnetic Many objects that appear to be nonferromagnetic field, might be approximately 8 feet from the magnet (e.g., wooden furniture) have been brought into MRI bore; and the 10,000 G, the strongest field for a 1 T scanner rooms only to be discovered to have con- magnet, will be at the entrance to the bore. The gauss cealed ferromagnetic components. For this reason, line distances are available from the specific MR sys- effective screening of items, equipment, or belongings tem suppliers. The 5 G line is cited as the boundary at that have not been specifically tested and labeled for which the magnetic field strength has diminished suffi- use in the MRI scanner room should be conducted. ciently to pose no physical threat to the general public Many objects can be effectively tested with high- or, more specifically, to individuals with implanted car- strength permanent magnets or, as discussed later in diac devices. Ferromagnetic objects placed within the this article, ferromagnetic-only detection systems. 5 G line could be drawn into the magnet, and many devices may fail to operate properly.1 Some medical MRI Magnetic Field Strength Relative to devices are designed for use in the MR environment; Distance from Magnet however, these devices have conditional uses relative The magnetic field extends as a 3-D volume outside to specific MR environments (i.e., medical devices the scanner and is known as the fringe field. For con- designed for use in one MR environment cannot be venience, the magnetic field is often mapped using used in all MR environments). gauss lines, which are lines of equal magnetic field strength; gauss is abbreviated “G.” For the transla- Terminology for MRI-Specific Medical Devices tional (attractive) force, the field strength increases, Old Terminology usually very rapidly, approaching the entrance of In 1997, in a draft guidance document,* the Center the magnet bore. The gradient of the gauss lines are for Devices and Radiological Health (CDRH) of the roughly analogous to the steepness of a mountain U.S. Food and Drug Administration (FDA) adopted slope. If the grade (gradient) is gentle, the slope is rea- terminology from the American Society of Testing sonably safe, regardless of how high on the mountain and Materials (ASTM) International—MR Safe and you are. If it is very steep, such as at a cliff, the risk of MR Compatible—to help characterize the safety of med- falling becomes more immediate and dangerous, again ical devices in the MR environment. The guidance regardless of how high you are on the mountain. It called for devices designed for use in a MR environ- should be noted that the MR gradient is higher when ment to be marked with these terms to distinguish the field strength lines are closer together. them from devices contraindicated for use in MR The distance of these gauss lines from the magnet environments. The terms in the 1997 guidance docu- bore largely depends on the magnetic shielding used. ment are defined as follows:4 When shielding is used, the magnetic field drops off MR Safe: “The device, when used in the MR envi- very steeply, which means that an object needs only ronment, has been demonstrated to present no to move a small distance (e.g., about 1 inch) from additional risk to the patient, but may affect the qual- experiencing no force effect to becoming uncontrol- ity of the diagnostic information.” lable. Modern systems use active shielding, which MR Compatible: The device, when used in the MR helps confine the fringe field close to the magnet’s environment, is MR Safe and has been demonstrated to neither significantly affect the quality of the diag- nostic information nor have its operation affected by Table 3. Ferromagnetic Items That Were the MR device.” Almost Brought into MRI Scanner Rooms Reported to the Pennsylvania Patient The guidance document also states that the use of Safety Authority, June 2004 through these terms “without specification of the MR envi- December 2008 ronment to which the device was tested should be avoided since interpretation of these claims may vary FERROMAGNETIC ITEMS QUANTITY OF ITEMS and are difficult to substantiate rigorously.”4 This Oxygen tank 2* statement refers to the fact that any device designed Stretcher 2* for use in a MR environment has not been tested Wheelchair 1 and validated for use in all MR environments. For Total 5 * One oxygen tank and one stretcher were recorded on the same report submitted to the Authority. * “A Primer on Medical Device Interactions with Magnetic Reso- nance Imaging Systems”4 Page 58 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Vol. 6, No. 2—June 2009 Pennsylvania Patient Safety Advisory example, a device designed and tested for use with MR CONDITIONAL: “An item that has been demon- MRI systems with magnetic fields up to 1.5 T may strated to pose no known hazards in a specified be contraindicated for use with systems above 1.5 T MR environment with specified conditions for use. (e.g., 3 T MRI systems). Additionally, devices designed Field conditions that define the specified MR envi- for use in MR environments typically have restrictions ronment include field strength, spatial gradient, dB/dt on the placement distance from the magnet bore. For (time rate of change of the magnetic field), radio-fre- example, an infusion pump designed for use in a 1 T quency (RF) field, and specific absorption rate (SAR). MRI system may be restricted to no closer to the mag- Additional conditions, including specific configura- net than the 150 G line. In this example, the pump tions of the item, may be required.” brought closer to the magnet than the 150 G line could MR UNSAFE: “An item that is known to pose hazards be pulled to the magnet bore, potentially resulting in in all MR environments.” serious or fatal injuries to individuals near the magnet. A note within the definition states that “MR While, in theory, this terminology was developed UNSAFE items include magnetic items such as a pair to help users better understand the MR safety char- of ferromagnetic scissors.” [Emphasis added.] acteristics of medical devices, in practice, it has also Although the term “safe” is used in both nomencla- created confusion. Distinguishing between the two ture systems, the main difference between the old terms may often be misunderstood if users are not MR Safe term and the new MR SAFE term is that aware that devices have been validated for use under devices labeled safe under the old terminology are specific MR conditions such as a maximum magnetic understood to be safe under specific MR conditions field strength. The terms are also often mistakenly (e.g., magnetic field strength), whereas devices labeled used interchangeably, adding to the confusion. Both safe under the new terminology are understood to terms indicate no additional risks to individuals be safe for all MR conditions without exception. The in specific MR environments. However, a device new MR SAFE term has no limitations or restrictions, designated as MR Safe may affect the diagnostic infor- unlike the old MR Safe term. Therefore, the new term mation of the scan, while a device designated as should reduce confusion regarding devices brought MR Compatible will not affect the diagnostic informa- into the MRI scanner room. The icon representing tion, which means that not all MR Safe devices are MR SAFE consists of two versions of the letters “MR” also MR Compatible. Because of this, users may not surrounded by a green square as shown in Figure 1. be sure when it is, or is not, appropriate to use equip- ment as MR Safe or MR Compatible.6 The new MR CONDITIONAL term should also reduce confusion regarding devices brought into the New Terminology MRI scanner room, since the word “conditional” In 2005, in an effort to reduce or eliminate the will specifically alert clinicians that the device has confusion with the old terminology, ASTM Inter- national introduced a new standard* for marking medical devices for safety in the MR environment. Figure 1. ASTM Recommended Icon Associated with the MR SAFE ASTM Term The ASTM standard defines three terms to be used for permanently marking medical devices that may be brought into the MR environment. Unlike the old terminology, the new terminology does not include image quality considerations because, as stated in the standard, image artifact is not considered a safety issue for the purposes of the standard. The three new ASTM terms are MR SAFE, MR CONDITIONAL, and MR UNSAFE. (For the purposes of this article, to distinguish between the old terminology and the new terminology, italicized font represents the old terminology, and the new terminology is capitalized). The new terminology is defined as follows:5 MR SAFE: “An item that poses no known hazards in all MR environments.” A note within the definition states “MR SAFE items include nonconducting, nonmagnetic items such as a plastic Petri dish. An item may be determined to be MR SAFE by providing a scientifically based rationale rather than test data.” [Emphasis added.] Reprinted with permission from ASTM F2503-08 Standard Practice for * “Standard Practice for Marking Medical Devices and Other Items Marking Medical Devices and Other Items for Safety in the Magnetic for Safety in the Magnetic Resonance Environment”5 Resonance Environment, ©ASTM International. Vol. 6, No. 2—June 2009 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Page 59 Pennsylvania Patient Safety Advisory limitations or restrictions when brought into the MRI MR Safety Screening for Potential Projectiles scanner room. The icon for MR CONDITIONAL The March 2009 Pennsylvania Patient Safety Advisory consists of the letters “MR” within a yellow equilateral article on MR safety screening processes focused on triangle with a black band around the edge of the clinical screening of patients for exposure to metal symbol, as shown in Figure 2. The new MR UNSAFE that could compromise the safety of the patient or term should greatly reduce, if not eliminate, projectile the quality of the image diagnostic information of the risks due to the explicitness of the term (i.e., if a device scan. However, MR safety screening also encompasses is marked MR UNSAFE, it does not belong in the screening for ferromagnetic objects, external to the MRI scanner room). The MR UNSAFE icon consists patient, which if allowed into the MRI scanner room, of the letters “MR” surrounded by a red circle with a could potentially become dangerous projectiles. In diagonal red line across the diameter of the circle over addition to MR personnel checking to ensure that top of the letters, as shown in Figure 3. ferromagnetic objects do not make their way into the The new MR safety marking standard will only MRI scanner room, any facility personnel with access be effective if it is well understood and properly to the scanner room must be aware of which objects implemented by device manufacturers and MR are permitted and restricted from entering the scan- departments. Confusion may still exist, and there still ner room. This includes knowing and understanding may be an adjustment period as manufacturers and the ASTM MR safety device markings and, as applica- users migrate from the old nomenclature to the new ble, the safety conditions of each piece of equipment. nomenclature. Users may still see a mix of devices with the old MR safety markings and the new safety The Use of Ferromagnetic Detection Systems markings. During this period, users must know how A method that may help in screening for ferromag- to interpret the various device markings and how to netic objects that are external to the patient is the ascertain which devices can and cannot be used in a use of ferromagnetic-only detectors. The March 2009 particular MR environment.6 One way for facilities to Advisory article discussed the use of ferromagnetic- reduce confusion between the old and new terminolo- only detectors as an adjunct to the MR safety gies is to consult with equipment suppliers to obtain screening process that may significantly reduce the the information needed to relabel equipment with likelihood of objects becoming projectiles in the the new markings as soon as possible. MR environment. Ferromagnetic-only detectors are designed to distinguish between ferromagnetic and nonferromagnetic materials. The detectors warn Figure 2. ASTM Recommended Icon Associated with the MR CONDITIONAL ASTM Term MR personnel of the presence of ferromagnetic items external to the body (the detectors are not cur- rently approved for use in detecting ferromagnetic implants) before the item is brought into the MRI scanner room. The use of these detectors may sig- nificantly reduce the likelihood of objects becoming projectiles in the MR environment. A University of Pittsburgh Medical Center study demonstrated that ferromagnetic detectors were successful in detecting ferromagnetic items, even items as small as a safety pin, on patients before MRI scans.6 The University of Pittsburgh study also found that 44% of patients Reprinted with permission from ASTM F2503-08 Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic who indicated that they had complied with the MR Resonance Environment, ©ASTM International. screening instructions to remove all loose metallic objects before the MRI scan set off the ferromagnetic detector. This may suggest that patient compliance Figure 3. ASTM Recommended Icon Associated with with MR screening instructions for metallic objects the MR UNSAFE ASTM Term may not be comprehensive. Ferromagnetic-only detec- tors may not only be prudent for detecting larger ferromagnetic objects before entering the MRI scan- ner room, but may also prove useful as an adjunct practice in the MR patient screening process. The use of ferromagnetic-only detectors has been recommended by the American College of Radiology (ACR) in its 2007 “ACR Guidance Document for Safe MR Practices” and the U.S. Department of Veterans Affairs (VA) in its 2008 “VA Magnetic Resonance Reprinted with permission from ASTM F2503-08 Standard Practice for Imaging Design Guide.” Use of ferromagnetic-only Marking Medical Devices and Other Items for Safety in the Magnetic detectors has been cited as an approved means of Resonance Environment, ©ASTM International. screening verification in the Joint Commission’s Page 60 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Vol. 6, No. 2—June 2009 Pennsylvania Patient Safety Advisory Sentinel Event Alert Issue No. 38 “Preventing Acci- equipment damage, including emergency shutdown dents and Injuries in the MRI Suite.”7-9 of the MRI scanner, resulting from ferromagnetic pro- jectiles can be significant. The VA National Center Medical Device Malfunction in the for Patient Safety recently published information on MR Environment the average cost of a ferromagnetic projectile event In addition to the projectile effect, another safety in a VA facility to be $43,172 (excluding lost revenue concern is malfunction of medical devices in the and legal expenses).10 The VA also indicated that the MR environment. The proper operation of medical cost of an emergency shutdown of the MRI scanner, devices can be affected by the static, RF, and gradient known as “quenching the magnet,” can range from magnetic fields of MRI systems. (For a discussion of $20,000 to $500,000.10 the static, RF, and gradient magnetic fields, see the sidebar “Basic Operating Principles of Magnetic Reso- Conclusion nance Imaging.”) Ferromagnetic objects in the MRI scanner room can The static magnetic field can affect devices that incor- pose a serious, even catastrophic, projectile risk to porate components such as analog gauges or electric individuals in the room. Additionally, the magnetic motors, which contain magnets and coils (e.g., ventila- field can affect the operation of devices brought into tors, infusion pumps), or electronic components such the field. A good understanding of equipment and as transformer or relays. The effects can cause devices objects that can and cannot be brought safely into to malfunction or completely stop operating, poten- the MR environment will help reduce or eliminate tially resulting in serious patient harm. ECRI Institute the likelihood of projectiles or device malfunctions, cites one example of a patient-controlled analgesic thereby reducing the potential for serious harm to infusion pump that malfunctioned in the presence of individuals within the MR environment. a static magnetic field.1 The field caused the pump’s As part of a risk reduction strategies to reduce or motor to reverse direction without indication to the eliminate the possibility that objects will become user. Because of the reversed motor action, the pump projectiles or that medical devices will malfunction, could have drawn blood from the patient into the IV consider the following: line. However, the IV tubing incorporated a one-way ■ Identify the four MR safety boundaries as defined valve that prevented backflow of blood.1 by ACR in its “ACR Guidance Document for Devices that rely on magnetization to attach to a Safe MR Practices.” Mark the boundaries with patient (e.g., otologic implants) can become demag- netized in the static magnetic field of the scanner.1 Implanted devices that are magnetically, electrically, or mechanically activated, which may be affected by Basic Operating Principles of Magnetic the static magnetic field, are typically contraindicated Resonance Imaging for MRI scans. Other devices, such as those that measure physiologic electric signals (e.g., electrocar- Magnetic resonance imaging (MRI) creates cross- diogram [ECG] monitors) may be affected by high sectional images of anatomic structures placed in the magnet bore using (nonionizing radiation) field strength MRI systems (greater than or equal to electromagnetic fields. The static magnetic field 1 T).1 For example, high field strengths can distort of the MRI scanner causes the protons in the the ECG of patients within the field.1 The distortion body tissue to align in the direction of the static may appear as an increase in the amplitude of the magnetic field. Electromagnetic pulses from a T wave or ST segment of the signal, causing clinicians radio-frequency (RF) transmitter create an RF to believe the patient’s physiologic condition changed.1 magnetic field that alters the static magnetic field. The RF magnetic field can affect devices, such as When this occurs, the direction of the magnetized protons in the static magnetic field changes align- physiologic monitors, that incorporate lead wires (e.g., ment with that static field. When the pulses stop, ECG monitors, pulse oximeters). The lead wires act the magnetized protons revert to their original as antennas in the presence of the RF energy. The RF position. While reverting to their original position, energy of the MRI system can be electrically coupled to the protons emit RF energy that is detected by the lead wires if they are in close proximity to the MRI RF receivers of the MRI system. Computer analy- scanner. The coupling can result in temporary loss of sis then converts the signals into images of the the measured parameter or damage to the devices.1 The scanned anatomy. The gradient magnetic field is gradient magnetic field can mimic physiologic signals produced by coils inside the MRI system. The coils (e.g., ECG signals), and interfere with the ECG signal, are rapidly pulsed on and off during the time the which could cause misinterpretation of the ECG sig- RF magnetic field is pulsed. The gradient mag- netic field determines the location of the scanned nal.1 However, through design of physiologic monitors, anatomic section, the thickness, and the field of this interference can be eliminated using filtering and view of the section. digital signal-processing techniques.1 Source: ECRI Institute. The safe use of equipment The Price of Projectiles in the magnetic resonance environment [guidance Even in the absence of patient harm, the financial article]. Health Devices 2001 Dec;30(12):42-44. consequences of interrupted patient throughput or Vol. 6, No. 2—June 2009 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Page 61 Pennsylvania Patient Safety Advisory appropriate signage. Zone 4, the area contain- ■ Consider the use of ferromagnetic-only detection ing the MRI scanner that is associated with the systems as an adjunct to your facility’s MR safety strongest magnetic field, should be clearly marked. practices (based on the findings of the University Access should be restricted to this area without of Pittsburgh Medical Center study,1 and rec- supervision by appropriate MR personnel.1 (For ommendations from ACR7, VA8, and the Joint more information on the MR safety boundaries, Commission9). see the article “Safety in the MR Environment: Notes MR Safety Screening Practices” in the March 2009 issue of the Advisory.) 1. ECRI Institute. The safe use of equipment in the mag- netic resonance environment [guidance article]. Health ■ Provide training on MR safety considerations to all Devices 2001 Dec;30(12):421-44. MR staff and other personnel who may need access to the MRI scanner room. Include education 2. Chen DW. Boy, 6, dies of skull injury during MRI. on the new MR device terminology, the old MR NY Times [online]. 2001 Jul 31 [cited 2009 Mar device terminology, and the difference between the 23]. Available from Internet: http://www.nytimes. two nomenclatures.1 com/2001/07/31/nyregion/boy-6-dies-of-skull-injury- during-mri.html?n=Top/Reference/Times%20Topics/ ■ Prohibit equipment and devices within Zone 4 with- Subjects/C/Children’s%20Health. out first verifying that (1) they have been tested by the device manufacturer or properly trained expert 3. Beitia A, Meyers S, Kanal E, et al. Case report: spon- and (2) they have been labeled according to the taneous discharge of a firearm in an MR imaging envi- ronment. AJR Am J Roentgenol 2002 May;178(5):1092-4. ASTM device terminology—MR SAFE or MR CON- DITIONAL—for the specific MR environment.1 4. Center for Devices and Radiologic Health (CDRH) Mag- netic Resonance Working Group. A primer on medical ■ Maintain a list of MR SAFE, MR CONDI- device interactions with magnetic resonance imaging TIONAL (including conditions for safe use), and systems [draft online]. 1997 Feb [cited 2009 Mar 23]. MR UNSAFE equipment in every MR depart- Available from Internet: http://www.fda.gov/cdrh/ode/ ment or facility. When possible, identify the safety primerf6.html. conditions directly on an object or device. If MRI systems are upgraded or newly purchased, the MR 5. American Society of Testing and Materials (ASTM). safety officer determines whether the equipment Standard practice for marking medical devices and other is still MR SAFE, MR CONDITIONAL, or MR items for safety in the magnetic resonance environment. UNSAFE with the upgraded or new system.1 ASTM F2503-05. 2005 Aug:1486-92. ■ Do not alter MR SAFE or MR CONDITIONAL 6. ECRI Institute. What’s new in MR safety; the latest on equipment. Altering equipment may negate the the safe use of equipment in the magnetic resonance MR safety characteristics of the equipment.1 environment [guidance article]. Health Devices 2005 Oct;34(10):333-49. ■ Care should be taken when equipment contain- ing ferromagnetic components is brought into the 7. Kanal E, Barkovich A, Bell C, et al. ACR guidance docu- ment for safe MR practices: 2007. AJR Am J Roentgenol MR environment. For example, devices may be 2007 Jun;188(6):1447-74. validated for use in some areas of the MR environ- ment (e.g., field strengths not exceeding 150 G), 8. U.S. Department of Veterans Affairs (VA). VA MRI but not other areas.1 design guide [online]. 2008 Apr [cited 2009 May 20]. Available from Internet: http://www.cfm.va.gov/til/ — All equipment brought into the MR environ- dGuide/dgmri02.pdf. ment should be properly labeled (e.g., MR SAFE, MR CONDITIONAL) and should be 9. Joint Commission. Preventing accidents and injuries physically secured at a safe distance (defined in the MRI suite. Sentinel Event Alert Issue No. 38 by the equipment supplier) from the MRI [online]. 2008 Feb 14 [cited 2009 May 20]. Available system using nonmagnetic means (e.g., non- from Internet: http://www.jointcommission.org/ magnetic bolts), as appropriate. The method SentinelEvents/SentinelEventAlert/sea_38.htm. of restraint should be adequately tested before 10. U.S. Department of Veterans Affairs (VA) National implementation, and care should be taken to Center for Patient Safety. MR hazard summary [online]. protect the integrity of the RF shielding for 2008 Sept 29 [cited 2009 May 21]. Available from any attempt at providing anchorage within the Internet: http://www.va.gov/ncps/SafetyTopics/ MRI scanner room. mrihazardsummary.html. Page 62 REPRINTED ARTICLE - ©2009 Pennsylvania Patient Safety Authority Vol. 6, No. 2—June 2009 PENNSYLVANIA PATIENT SAFETY ADVISORY This article is reprinted from the Pennsylvania Patient Safety Advisory, Vol. 6, No. 2—June 2009. The Advisory is a publication of the Pennsylvania Patient Safety Authority, produced by ECRI Institute and ISMP under contract to the Authority. Copyright 2009 by the Pennsylvania Patient Safety Authority. This publication may be reprinted and distributed without restriction, provided it is printed or distributed in its entirety and without alteration. Individual articles may be reprinted in their entirety and without alteration provided the source is clearly attributed. This publication is disseminated via e-mail. To subscribe, go to https://www.papsrs.state.pa.us/ Workflow/MailingListAddition.aspx. To see other articles or issues of the Advisory, visit our Web site at http://www.patientsafetyauthority.org. Click on “Patient Safety Advisories” in the left-hand menu bar. THE PENNSYLVANIA PATIENT SAFETY AUTHORITY AND ITS CONTRACTORS The Pennsylvania Patient Safety Authority is an independent state agency created by Act 13 of 2002, the Medical Care Availability and Reduction of Error (“Mcare”) Act. Consistent with Act 13, ECRI Institute, as contractor for the Authority, is issuing this publication to advise medical facilities of immediate changes that can be instituted to reduce Serious Events and Incidents. For more information about the Pennsylvania Patient Safety Authority, see the Authority’s Web An Independent Agency of the Commonwealth of Pennsylvania site at http://www.patientsafetyauthority.org. ECRI Institute, a nonprofit organization, dedicates itself to bringing the discipline of applied scientific research in healthcare to uncover the best approaches to improving patient care. As pioneers in this science for nearly 40 years, ECRI Institute marries experience and independence with the objectivity of evidence-based research. More than 5,000 healthcare organizations worldwide rely on ECRI Institute’s expertise in patient safety improvement, risk and quality management, and healthcare processes, devices, procedures and drug technology. The Institute for Safe Medication Practices (ISMP) is an independent, nonprofit organization dedicated solely to medication error prevention and safe medication use. ISMP provides recommendations for the safe use of medications to the healthcare community including healthcare professionals, government agencies, accrediting organizations, and consumers. ISMP’s efforts are built on a nonpunitive approach and systems-based solutions.