Clinical authority

MR Medical Director (MRMD)

A named physician responsible for ensuring MR safe-practice guidelines are established and maintained as current and appropriate for the facility type. Holds the final determination on whether a patient is scanned.

• Defines the MR safety education content for Level 1 and Level 2 personnel.
• Typically delegates routine screening decisions to MR technologists through written policy, reserving consultation for cases where the decision is not straightforward. That delegation only works if the policy exists.
• Develops and implements staffing and training policy, including for remote scanning environments.
• Receives adverse event, near miss and good catch reports.

Policy test: does the document name the individual, state the duties, and specify the training and certification path, or does it only say that an MRMD exists?

Operational authority

MR Safety Officer (MRSO)

Day-to-day implementation. Frequently a highly trained technologist. ACR expects MRSO coverage by facility location per shift, not one name on an org chart covering a health system.

• Controls Zone III and Zone IV access decisions in real time.
• Maintains familiarity with the instructions for use for every MR system in the facility.
• Clears objects and equipment, and escalates to the MRMD or MRSE when advice is required.
• Maintains contact with the other committees that intersect the suite: quality, infection control, facilities, emergency management.

Policy test: is there named MRSO coverage for every shift the scanner runs, including evenings, weekends and any add-on capacity?

Technical authority

MR Safety Expert (MRSE)

A resource to the MRMD and MRSO for technical and physics questions: fields, gradients, RF heating, implant conditions, shielding, equipment behavior. Typically a medical physicist. Explicitly excludes contrast agents, anxiolytics and other pharmaceuticals, which belong to the MRMD.

• May be external to the organization, which makes this the most commonly neglected of the three roles in outpatient and independent settings.
• ACR expects the MRSE to be identified prospectively. The distinction matters: an MRSE located after a complex implant case arrives is a consultant, not a program element.

Policy test: is there a name, a contact method, and a defined response expectation, agreed before the first difficult case rather than during it?

Structural policies

• MR safety program charter and role appointments
• Zone designation, signage and access control
• Minimum staffing plan by area and shift
• MR safety education: levels, content, intervals, and the consequence of lapse
• Remote scanning staffing and responsibilities, where applicable
• Alternative MR environments: radiation oncology simulators, intraoperative suites, mobile units, point-of-care systems

Operational SOPs

• Patient, staff, companion and vendor screening
• Unreliable historian pathway
• Implant and device assessment, including unlabeled devices
• Object clearance and site designation of MR status
• Full stop and final check, routine and augmented
• Patient preparation, gowning, positioning and padding
• Hearing protection issue and fit verification
• Contrast administration, extravasation and reaction response
• Sedation, monitoring and discharge criteria
• Emergency response: medical, fire, security, quench
• Cryogen and quench pipe management
• Incident, near miss and good catch reporting
• Cleaning, infection control and medical waste in Zones III and IV
• Annual program review and re-endorsement

IEC 60601-2-33:2022 revised the fringe field limit from 5 gauss (0.5 mT) to 9 gauss (0.9 mT). The ACR Manual endorses the new standard and the FDA recognizes 9 gauss as the B0 hazard area.

The practical consequence is smaller than it first appears. The 9-gauss line sits inside the 5-gauss line, closer to the magnet. A facility that already treats the 5-gauss boundary as its hazard perimeter is more conservative than the current standard and needs no change. A facility redesigning to the new line is shrinking its controlled area and should document the physics review that supported it.

The historical 5-gauss line was the pacemaker line, derived from fringe field requirements for cardiovascular implantable electronic devices. That association is the reason it lingers in older policy language.

The 200-gauss line is the one people forget

ACR 2024 recommends marking a 200-gauss line on the Zone IV floor in addition to the 9-gauss line, because MR Conditional equipment labeling frequently stipulates a gauss limit, and 200 G is a common one. Tethers are then sized so that equipment physically cannot cross it.

Static field

B0: force, torque and projectiles

Always on. Generally constant within the bore and tapering quickly outside it. Two distinct forces act on ferromagnetic material and they peak in different places.

• Rotational torque is determined primarily by field strength and is greatest inside the bore. This is what turns an implanted device.
• Translational displacement tracks the spatial field gradient, the rate at which B0 changes with position, and is greatest near the bore entrance. This is what makes a projectile.

An object carried toward the face of the magnet experiences rapidly escalating force. The escalation is why intuition fails: the object that was controllable a step earlier is not.

Gradient field

dB0/dt: acoustic noise and nerve stimulation

Gradients switch rapidly for spatial localization. Strong switching currents in a strong static field produce large mechanical forces, and therefore sound.

• Systems can exceed 99 A-weighted decibels, the FDA threshold above which manufacturers must specify the hearing protection required.
• Induced currents can stimulate nerve and muscle. Under current gradient switching limits this is generally a comfort issue rather than a safety one, which is consistent with the FDA series finding no reports attributable solely to peripheral nerve stimulation.

Acoustic injury is where the gap between policy and practice is widest: protection is almost always available and frequently misapplied, and efficacy depends entirely on fit.

RF field

B1: heating and thermal injury

The transmitted B1 field generates electric fields in tissue, producing localized heating wherever local impedance is high. This is the mechanism behind 59 percent of all reported MRI adverse events.

• SAR, in watts per kilogram, estimates the rate of energy absorption. It bounds short-term heating.
• Specific energy dose, in joules or kilojoules per kilogram, is the total energy delivered across the examination. It bounds core temperature elevation and physiologic stress.

These are different quantities and they fail differently. A protocol within SAR limits can still deliver a large specific energy dose across a long examination.

What the object list is telling you

Transport and mobility equipment leads at 26 percent: wheelchairs, walkers, stretchers and chairs. Gas cylinders and magnet components exposed during service follow at 10 percent each. Tools, monitoring equipment, carts and IV poles fill the middle.

Almost none of these items arrive in a patient’s pocket. They arrive in the hands of someone doing their job: a transporter, a respiratory therapist, a service engineer, a cleaner, a firefighter. The FDA authors found that the individual responsible for introducing the projectile was typically someone other than the patient, and that few projectile events could be attributed to patient screening failures.

Firearms, floor polishers and firefighting equipment each appear in the series. These are not hypothetical categories invented for a training slide.

The July 2025 Westbury fatality

A 61-year-old man entered an MRI room at an outpatient center in Westbury, New York, while a scan was in progress, wearing a heavy metal chain used for weight training. He was drawn into the machine and died the following day. Police reported that his entry was not authorized. He was not the patient; his wife was on the table.

Every element of the failure sits in this dashboard: an unscreened non-patient, an unauthorized entry into Zone IV during an active scan, and an object whose ferromagnetic mass made the outcome inevitable once he crossed the threshold.

Acoustic

86 reported events involving tinnitus, hearing loss, or both, transient or permanent. The series included patients who were given protection and patients who were not, and at least one field service engineer. Efficacy depends on fit, and correct application is the facility’s responsibility, not the manufacturer’s.

The site checklist tests three things: protection required or recommended for any person in the room during the examination, user instruction on fit and function, and a named alternative when the first option is not feasible, such as ear muffs that will not fit inside a head coil or a patient who refuses foam plugs.

Mechanical

170 reported events, 11 percent, mostly not MR-specific: finger pinch at the moving table, falls, and staff injuries from moving heavy items. One injury type is MR-specific and worth naming in policy: 22 reports of rib fractures in patients undergoing breast examinations, because breast coils sit elevated from the table and increase the risk of collision with the bore.

Cryogen and quench

Three switches with three different consequences, and staff must know which is which: emergency stop halts scanning and table motion; emergency power off cuts electrical power to the suite and computer room including any UPS; emergency magnet off, the quench, rapidly collapses the magnetic field.

A quench is not a general emergency response. Policy must state when to quench rather than power off, and name exactly who is authorized to initiate it. One FDA death report involved a field service engineer who died following treatment for a cryogenic burn.

Contrast

Contrast is governed by the ACR Manual on Contrast Media rather than the MR safety manual, but it sits inside the MR safety policy set because the checklist tests for it. Four elements: distribution of FDA-required patient information forms, clinically acceptable risk thresholds covering renal function and prior allergic response, agent, dosing and delivery parameters, and the response to extravasation or reaction.

Adverse reactions to contrast agents were explicitly excluded from the FDA MR system series, so none of the event figures on this page include them.

Who gets screened

• Patients and research participants. Uniform, documented, every time. Not a form collected at reception and filed unread.
• Employees and caregivers working within the secured area. The site checklist asks for this explicitly and separately from patient screening.
• Companions and family entering Zone III or IV. The population implicated in the Westbury fatality and in roughly half of pediatric Zone IV events.
• Vendors, service engineers and contract trades. Screened and documented at every visit.
• Unreliable historians. A defined pathway for patients who are altered, impaired, sedated, non-verbal, or facing a communication barrier. The checklist names this as its own element because the standard screening process fails silently for these patients.

What screening has to produce

• Identification of implants and on-planted devices by type, location, make and model. Not category. Model.
• Identification of retained foreign bodies, including occupational metal fragments and retained ballistic projectiles.
• Removal of all clothing within the RF transmission range and gowning in site-supplied MR Safe pocketless garments.
• Confirmation that a scanner meeting the device-specific conditions is available.
• Assessment of whether the device will degrade the diagnostic value of the examination in the anatomy of interest, which is a reason to reconsider the study rather than to proceed and hope.
• Where physical screening adjuncts are used, a documented response protocol for a ferromagnetic detection alarm.

Cell phones deserve their own clause. They are common in Zone III and become projectiles in Zone IV. Pocketless scrubs for staff and secured Zone III storage address phones, keys and dressing scissors together.

Tier 1

Routine

The typical ambulatory setting. Immediately before entering Zone IV, MR safety screening is satisfactorily completed for:

• the patient,
• any support equipment accompanying them,
• any personnel entering with them.

Performed by the MR technologist. This is a stop, not a glance: the verification happens at the threshold, not at the desk twenty minutes earlier.

Tier 2

Augmented

More complex settings: hospitalized patients, interventional cases, intraoperative suites. Everything in the routine process, plus:

• thorough screening of all support staff entering Zone III or IV,
• screening of all transport and support equipment, including MR conditions and tethering,
• a verbal review by the supervising Level 2 MR technologist,
• an acknowledgement by a second MR personnel team member,
• in intraoperative settings, confirmation that the patient’s MR safety status has not changed, such as a device implanted during the procedure that morning.

Level 1

Not a danger to themselves or others

Content the MRMD should expect to see covered:

• The magnet is always on, including during power loss and outside business hours.
• Zone boundaries, what each zone permits, and where the person’s own authorization ends.
• The projectile hazard and the spatial gradient: why force escalates near the bore entrance.
• What may and may not be carried past the Zone III threshold, including personal items.
• Screening requirements that apply to them personally, every time, regardless of seniority.
• What to do if an object becomes attracted: clear, secure, notify. Do not pull.
• Emergency response inside Zone IV, and the difference between the three emergency switches.
• Hearing protection expectations for anyone in the room during a scan.
• How to report a near miss, and that reporting one carries no penalty.

Level 2

Broader aspects of MR safety

Everything in Level 1, plus:

• Field physics sufficient to reason about novel situations: B0, dB0/dt, B1, spatial field gradient, operating modes.
• RF heating mechanisms and the positioning and padding controls that address each of them.
• SAR versus specific energy dose, and what each one bounds.
• Implant and device assessment: ASTM labeling, conditions of use, active versus passive devices, the unlabeled pathway.
• Screening of unreliable historians, pediatric patients and pregnant patients or staff.
• Contrast, sedation and monitoring interactions with the MR environment.
• Full stop and final check, routine and augmented, including the second-person acknowledgement.
• Quench and cryogen response, and who is authorized to initiate.
• Supervision of non-MR personnel in Zones III and IV.

ACR notes that further stratification within Level 1 and Level 2 may be needed for alternative MR environments such as intraoperative suites, radiation oncology simulators and mobile units.

Before the appointment

What the booking call must establish

• Any implanted or worn device, by name where the patient knows it. Pacemakers, defibrillators, neurostimulators, pumps, cochlear implants, shunts with adjustable valves, insulin pumps, continuous glucose monitors, hearing aids.
• Any surgery involving hardware: plates, screws, rods, clips, coils, stents, joint replacements.
• Any history of metal working, grinding or welding, and any prior injury involving metal fragments or a retained ballistic projectile.
• Pregnancy, or the possibility of pregnancy.
• Claustrophobia, anxiety, or a previous examination that could not be completed.
• Body habitus considerations, which affect bore contact risk rather than eligibility.
• Whether the patient will need a companion in the room, which converts that companion into a person requiring full screening.

A scheduler who cannot recognize an implant keyword pushes the failure downstream to a person holding a patient at the Zone III threshold under time pressure. This is why schedulers appear in the role matrix at Level 1 with a screening module.

On arrival

What the patient should be told, in plain words

• The magnet is always on. Not only during the scan. Not switched off between patients.
• Everything metal comes off, and clothing comes off too. Site-supplied pocketless gowns are not a formality. Electrically conductive and metallic-thread fabrics have caused burns, and a pocket is where a forgotten key lives.
• Tell us about anything inside you, even if you think it does not count. Including tattoos and permanent makeup, dermal patches, piercings that cannot be removed, and anything a previous facility told them was fine.
• You will hear loud knocking, and the hearing protection is not optional. Explain the fit; a plug that is not seated does very little.
• You must lie still, and there is a way to reach us. Demonstrate the call device or squeeze ball and confirm the patient can operate it in position.
• If any part of you starts to feel warm, tell us immediately. Do not wait for it to become painful. Do not wait for the sequence to end.
• Keep your arms and legs from touching each other or the side of the tunnel. Explain that the padding is doing a job.

Language access

Medical translator or interpreter services when a patient’s language proficiency does not match that of the MRI staff. This appears in the site checklist as a patient communication element, and it belongs there rather than in a service-quality policy: screening is an interview, and an interview conducted through a family member is an interview with an unverified intermediary answering implant questions.

Continuous contact

A patient notifier device such as a squeeze ball, or continuous acoustic monitoring such as an open intercom channel, during examinations of conscious patients. Both are acceptable; having neither is not. Confirm before the table moves that the patient can actually operate the device in the position they will hold.

Pregnancy

Patients and staff, two separate policies

Patients. Available research has not demonstrated harm to the pregnant person or the fetus from the fields used in routine clinical MRI at 3 T or below. ACR supports clinical use up to 3 T in Normal Operating Mode, whole-body averaged SAR of 2 W/kg, where benefit is expected and no other practical route to the same information exists. Above 3 T the risks are unknown. ACOG considers MRI and ultrasound the imaging techniques of choice in pregnancy, used prudently and where medical benefit is expected.

Staff. A separate occupational statement addressing static and time-varying field exposure, defining which workplace activities are permitted and which are restricted. The site checklist asks for both. Most programs write the first and omit the second.

Pediatrics

Two screenings, not one

The checklist asks for both parent or guardian screening and private clinical screening for pediatric and adolescent patients. The private component exists because an adolescent may not disclose a piercing, a pregnancy or a device in front of a parent.

Caregivers are frequently brought into the scanner room to comfort a child, which is the mechanism behind the finding that 47 percent of pediatric Zone IV events did not directly involve the patient. A caregiver entering Zone IV is screened to the same standard as staff, every time, including on repeat visits.

Sedation and anesthesia

The equipment arrives with the clinician

The checklist tests two distinct things. First, actions for self-medicated patients, competency to consent, and discharge or release-to-drive criteria. A patient who took their own anxiolytic before arriving is sedated whether or not the facility sedated them.

Second, specific MR safety training and competency requirements for clinicians providing supporting monitoring or care during exams, naming anesthesia and respiratory explicitly. They arrive with ventilators, pumps, laryngoscopes and monitors, each of which is an object clearance decision.