Universal MRI Patient Preparation & Safety

Universal Patient Preparation for Magnetic Resonance Imaging

A Comprehensive Evidence-Based Reference Document

1. Introduction and Rationale

Magnetic resonance imaging represents one of the most diagnostically powerful and physiologically complex modalities in modern medical imaging. Unlike radiography, fluoroscopy, or computed tomography, the safety risks associated with MRI do not arise from ionising radiation but from three distinct physical phenomena that are active continuously during scanner operation: the static magnetic field (B0), the time-varying gradient magnetic fields (dB/dt), and the radiofrequency (RF) electromagnetic field (B1). Each of these constitutes a distinct hazard profile with specific relevance to patient preparation, device screening, and environmental control [1,2].

The consequences of inadequate pre-procedural patient preparation in MRI are disproportionately severe compared with other imaging modalities. Projectile accidents involving ferromagnetic objects, thermal injuries from RF-induced heating of conductive implants or clothing, and device malfunction in patients with active implants are all potentially life-threatening and largely preventable through rigorous, standardised preparation protocols. Deaths and serious injuries have occurred in MRI facilities; such events are most commonly linked to unsafe practices, failure to follow MRI safety policies, or gaps in safety policies and standard operating procedures — equipment failures are rarely the primary cause [1].

The elements of patient preparation described in this document are universal. They apply to every patient, every anatomical region, and every field strength from 1.5 T to 7 T. Preparation elements that are specific to individual anatomical districts or clinical indications (e.g., bowel preparation for MR enterography, bladder filling protocols for pelvic MRI) are intentionally excluded and are addressed in protocol-specific child documents.

2. The ACR Four-Zone Safety Model: Structural Framework for Patient Preparation

Patient preparation does not occur in isolation but is embedded within a physical and operational safety architecture: the four-zone model of the American College of Radiology (ACR) [1,3]. Within that model patients are brought into the procedural workflow in Zone II, where they change into MR-safe gowns and are screened for MR safety issues, with supervision required, and the scanner room is Zone IV [1]. The definition of each zone, the access rules by category of person, locks, signage, supervision and emergency access are in MR Site Zones and Access Control; the meaning of the 0.5 mT (5 G) and 0.9 mT (9 G) lines and the restrictions attached to them are in Static Magnetic Field Contours; terminology and roles are in MRI Safety — Master Page. This zonal framework directly governs the sequence and location of all patient preparation activities.

3. Pre-Examination Safety Screening

3.1 Rationale and Mandatory Nature

Safety screening is the single most critical operational step in MRI patient preparation. It is mandatory without exception for every individual — patient, companion, or staff member — prior to entry into Zone III [1].

The ACR recommends a two-level screening process for non-emergent patients:

The first level of screening should take place when the examination is ordered. The MRI staff member scheduling the examination should have basic training in MRI safety and should pose a brief set of screening questions to the referring healthcare provider ordering the study. At a minimum, these questions should include: whether the patient has any implanted cardiac devices (pacemakers, wires, defibrillators) or other active devices (cochlear implants, neurostimulators, infusion pumps); the presence of a cerebral aneurysm clip; and any known metal fragments in critical locations such as the orbit [1].

The second level of screening is performed in Zone II at the time of the examination, consisting of a comprehensive written questionnaire followed by a verbal review with an MRI-trained technologist.

3.2 Standardised Screening Questionnaire: Domains of Inquiry

The screening questionnaire must systematically address the following domains. Each category carries a specific risk profile relative to the three MRI field hazards.

3.2.1 Cardiovascular Implantable Electronic Devices (CIEDs)

Cardiac implantable electronic devices — including pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronisation therapy (CRT) devices — pose significant risks during MRI [1,20]. The hazards, the categories of system, the decision pathway, programming, monitoring, post-scan checks and the points on which the published frameworks differ are in Cardiac Implantable Electronic Devices in MRI; the ACR Manual refers the management of these patients to the Heart Rhythm Society consensus document [1].

All patients with implanted cardiac pacemakers, implantable cardioverter-defibrillators, diaphragmatic pacemakers, medication pumps, cochlear implants, or other electromechanically activated devices should be precluded from entering Zone IV and prevented from passing the 9-G line unless specifically cleared in writing by a Level 2 MRI Physician or the MRI Medical Director. Documentation defending the risk-benefit rationale must be provided in writing [1].

3.2.2 Intracranial Aneurysm Clips and Neurovascular Devices

Ferromagnetic aneurysm clips represent one of the most historically significant absolute contraindications to MRI. The hazard is displacement of the clip within the cerebral vasculature, with risk of catastrophic haemorrhage. It is essential to ascertain the manufacturer, model number, and material composition of any such clip before proceeding. If it is unclear whether a patient has an implanted intracranial aneurysm clip, plain films should be obtained. Alternatively, if available, recent cranial plain films, CT, or MRI examinations should be reviewed to assess for the presence of such a clip [1].

Critically, a patient with an aneurysm clip who has previously undergone MRI safely at any given field strength cannot be assumed to be safe for subsequent examinations. Variations in static field strength, static field gradient, and orientation of the clip relative to the static field are variables that are impossible to control or reproduce across separate examinations [1]. The evidence on aneurysm clips (incident databases, the first fatal case, estimates by implantation year) is in Passive Implants and Retained Foreign Bodies in MRI.

3.2.3 Other Implanted Devices and Foreign Bodies

The screening questionnaire must address the full spectrum of implanted devices that may interact with one or more MRI fields:

Device Category               | Primary Hazard                         | Action Required

------------------------------|----------------------------------------|--------------------------------------------------- Cochlear implants, neurostimulation systems and infusion pumps: manufacturer and model verification of the complete system is required, and the evidence and device-specific points are in Active Implants Other Than Cardiac Devices in MRI Orthopaedic implants, ocular and orbital foreign bodies, bullets, shrapnel and fragments: evidence and decision structure in Passive Implants and Retained Foreign Bodies in MRI Penile implants, expanders | Displacement, heating | Manufacturer verification required Retained cardiac leads | Heating via antenna effect | Specific precautions required

All patients with a history of injury or implantation associated with a ferromagnetic foreign body must undergo further investigation prior to being permitted entry to Zone III. Acceptable methods include patient history, plain radiographs, prior CT, or documentation of implant type and material [1].

Particular attention is required for patients with a history of occupational metalwork (grinding, welding, metal lathe operation), military service, or trauma: these populations carry increased probability of occult orbital or intra-ocular metallic foreign bodies. Patients with a history of foreign bodies in the eyes will require a negative CT of the orbits prior to admission to Zone III/IV; if CT is not available, skull radiographs in two projections constitute an acceptable alternative [1].

3.2.4 MRI Safety Classification Terminology

The terms MR Safe, MR Conditional, MR Unsafe and MR Unlabelled are defined, with their sources, in Section 4 of MRI Safety — Master Page; how a test result becomes the conditions printed on an MR Conditional label, and how to match that label to the scanner, is covered in Implant and Device MR Safety Framework. The classifications apply equally to in-dwelling implants and to external devices including monitoring equipment, infusion pumps, wheelchairs and patient transport hardware.

3.3 Screening of Unconscious or Incapacitated Patients

Unconscious, sedated, or cognitively impaired patients represent a critical safety challenge, as reliable history cannot be obtained from the patient directly. Family members or guardians of such patients should complete a written MRI safety screening questionnaire prior to the patient's introduction to Zone III. If no reliable patient history can be obtained and the MRI cannot reasonably be delayed, such patients should undergo plain-film radiography of the anatomical regions in question to exclude potentially harmful embedded implants [1].

3.4 Ferromagnetic Detection Systems

Ferromagnetic detection systems are an adjunct to, and not a replacement for, screening of persons and devices before entry into Zone IV [1]; the guidance is held in the MR Site Zones and Access Control page (Section 7.2) and the evidence on their use in Projectile and Torque Hazards in the Static Field.

4. Patient Clothing, Personal Effects, and RF Heating Considerations

4.1 Removal of External Metallic Objects

All patients must remove all externally worn metallic items prior to entry into Zone III. This requirement is absolute and non-negotiable. Items to be removed include, but are not limited to:

• Jewellery of any type (rings, necklaces, bracelets, earrings, body piercings)
• Watches and wearable electronic devices (smartwatches, fitness trackers)
• Hearing aids (external, non-implanted type)
• Hairpins, clips, barrettes, and metallic hair accessories
• Dental appliances that are removable (dentures, removable orthodontic retainers)
• Glasses and spectacles with metallic frames
• Keys, coins, and all pocket contents
• Transdermal medication patches containing metallic components
• Clothing with metallic zippers, clasps, underwire brassières, metallic threads or fibres

The 2024 ACR Manual recommends that patients or research participants remove all clothing, including undergarments, when within the range of RF transmission — for example, within the scanner bore when the built-in body coil is used for RF transmission — and wear site-supplied MR Safe pocketless garments [1].

4.2 Textile Safety and Conductive Fabrics

Clothing containing electrically conductive fibres (for example silver or copper antimicrobial fabrics) or metal components such as zippers can heat in the RF field [9]. The mechanism, the evidence and the limits of that evidence are in RF Heating and Burns. Wearable technology devices that incorporate heart rate or respiratory sensors built into clothing should be treated as MR Unsafe and removed before scanning.

All patients should change into facility-provided MR Safe pocketless gowns or scrubs. Site-provided garments eliminate the risk from unknown textile composition and pocket contents simultaneously.

4.3 Tattoos, Permanent Cosmetics, and Topical Metallic Products

Tattoos have been linked with heating and RF burns, and ferromagnetic pigments in some tattoos may also interact with the static field [9,16]. The evidence on burns and the way it is limited are in RF Heating and Burns (Section 7).

In permanent cosmetic tattoos, the use of iron oxide pigments, sometimes containing the ferrimagnetic substance magnetite, has been identified as a potential ingredient for MRI interactions. The formation of artefacts from permanent eyeliners or eyebrow tattoos during MRI of the head is a recognised phenomenon [16].

In practical terms, the current evidence does not support systematic exclusion of tattooed patients from MRI. The appropriate clinical approach includes:

• Documenting the presence, location, colour, and age of all tattoos and permanent cosmetics;
• Informing patients of the possibility of transient burning or tingling sensations in the tattooed area during the examination;
• Instructing patients to use the emergency alert device immediately if discomfort occurs;
• Applying a cool compress over the tattooed area prior to scanning in high-risk cases.

Makeup, nail polish, and other cosmetics that may contain metallic particles should be removed if applied to the area of the body undergoing MRI examination. This applies particularly to metallic eye shadow, eyeliner, and mascara in patients undergoing brain or head and neck MRI [1].

All transdermal drug delivery patches should be assessed for metallic content. Patches with conductive backing represent a documented burn risk and, where clinically safe, should be removed prior to scanning and replaced after the examination.

5. Patient Identification and Clinical History Verification

Before any patient proceeds to Zone III, positive identification must be confirmed using at least two independent patient identifiers (e.g., full name and date of birth, or full name and hospital identification number). This step is essential to prevent wrong-patient examinations and to ensure that the screening information obtained corresponds to the individual who will undergo the procedure.

Clinical history verification must include:

• Confirmation of the clinical indication and appropriate referral
• Current medication list (particularly anticoagulants, antidiabetics, and metformin)
• Allergy history (with specific emphasis on prior reactions to gadolinium-based contrast agents and on atopic status)
• Prior surgical history (to identify implants that the patient may not recall or be aware of)
• Occupational history (to identify risk of ferromagnetic foreign body exposure)
• Prior MRI history and any documented difficulties (claustrophobia, motion-related scan failure, prior adverse reactions to contrast agents)

6. Pregnancy and Lactation Assessment

6.1 MRI Without Contrast in Pregnancy

Ultrasonography and magnetic resonance imaging are not associated with risk and are the imaging techniques of choice for the pregnant patient, but they should be used prudently and only when use is expected to answer a relevant clinical question or otherwise provide medical benefit to the patient [5].

The statements of the guidelines on trimester, operating mode, field strength and consent, the epidemiological evidence on outcomes after first-trimester MRI and the arrangements for pregnant staff are in MRI in Pregnancy and the Pregnant Worker. The pregnancy screening questions remain in Section 6.3 below.

6.2 MRI with Gadolinium-Based Contrast Agents in Pregnancy

The statements on gadolinium-based contrast agents in pregnancy, the cohort studies and the points on which the guidance differs are in Gadolinium-Based Contrast Agent Safety (Section 9).

6.3 Pregnancy Screening Protocol

All women of childbearing age must be asked about current or possible pregnancy before MRI, and specifically before any contrast-enhanced MRI. There is variability in the accuracy of pregnancy tests early in gestation, and at a minimum, testing will be falsely negative in the first two weeks of pregnancy; no screening method is 100% effective in detecting unsuspected pregnancy [7]. Regardless of the screening method employed, women of childbearing age should be informed of this uncertainty prior to any gadolinium-enhanced MRI.

6.4 Breastfeeding and Gadolinium-Based Contrast Agents

The statements on breastfeeding after a gadolinium-based agent are in Gadolinium-Based Contrast Agent Safety (Section 10).

7. Evaluation of Renal Function Prior to Gadolinium-Based Contrast Administration

7.1 Nephrogenic Systemic Fibrosis: Risk Stratification

NSF, the agent groups and the numbers behind them are in Gadolinium-Based Contrast Agent Safety (Sections 3 and 4).

7.2 ACR Classification of GBCAs and Current Risk Assessment

The ACR groups and the way they differ from the European classification are in Gadolinium-Based Contrast Agent Safety (Section 3).

7.3 Renal Function Screening Protocol

Screening, thresholds, dialysis, consent and repeat dosing, with the points on which the ACR-NKF consensus and the RCR guidance differ, are in Gadolinium-Based Contrast Agent Safety (Section 5).

8. Prior Contrast Agent Reaction History and Premedication Considerations

8.1 Incidence and Classification of Acute Hypersensitivity Reactions to GBCAs

Reaction rates, risk factors and observation are in Gadolinium-Based Contrast Agent Safety (Section 7).

8.2 Premedication Protocols

The evidence on premedication and change of agent is in Gadolinium-Based Contrast Agent Safety (Section 8).

9. Anxiety, Claustrophobia, and Patient Psychological Preparation

9.1 Frequency and Measures to Reduce Anxiety and Claustrophobia

The frequency of claustrophobia in MRI, the prediction by the Claustrophobia Questionnaire, the evidence on information, relaxation and cognitive strategies, scanner design and positioning, and the preparation of children are in Claustrophobia, Sedation, Monitoring, Equipment and Emergencies in the MR Environment (Sections 3 to 5).

9.2 Pharmacological and Practical Points

Pharmacological techniques for severe patient anxiety include anxiolytic medications such as benzodiazepines, warm blankets, panic buttons for immediate communication, and relaxation techniques including grounding, meditation, and deep breathing exercises. Open MRI systems or alternative imaging modalities represent the option of last resort for patients with refractory claustrophobia [13].

Patients receiving benzodiazepines for MRI-related anxiety must be accompanied by a responsible adult for transport and should be informed not to operate motor vehicles on the day of the examination. Paediatric sedation and general anaesthesia for MRI are specialised procedures requiring separate protocols addressing anaesthetic safety in the magnetic environment.

10. Fasting and Dietary Preparation

10.1 General Principles

Routine MRI examinations of the brain, spine, and musculoskeletal system do not require fasting in the absence of sedation, anaesthesia, or specific protocol requirements. The rationale for fasting where applicable relates to:

1. Reduction of aspiration risk in patients receiving sedation or general anaesthesia: fasting is mandatory in accordance with anaesthetic society guidelines (typically at least 6 hours for solids and 2 hours for clear fluids in adults).
2. Image quality optimisation for abdominal and pelvic studies: gastrointestinal peristalsis and luminal content can produce motion artefacts and reduce visualisation of adjacent structures.
3. Reduction of nausea risk associated with GBCA administration: this rationale is less clearly supported by current evidence. Recent observational data suggest that pre-procedure fasting does not significantly reduce the incidence of nausea or vomiting following GBCA administration; however, many institutional protocols continue to recommend 2-4 hours of fasting before contrast-enhanced MRI as a precautionary measure.

10.2 Protocol-Specific Fasting Requirements

The following summary reflects common institutional practices and is provided for orientation. Individual protocol-specific requirements supersede these general ranges and are specified in the corresponding child documents:

Examination Type                              | Typical Fasting  | Free Fluid

----------------------------------------------|------------------|---------------------------- Brain, spine, MSK (no sedation, no contrast) | None | None Brain, spine, MSK (with GBCA, no sedation) | None to 2 h | Water permitted Cardiac MRI (anatomical) | None | No caffeine 24h for stress Cardiac MRI (adenosine stress protocol) | 4 h | No caffeine 24h pre-exam Abdominal/pelvic MRI (with GBCA) | 4-6 h | Water permitted MRCP | 4-6 h | Water permitted MR Enterography | 4 h | Oral contrast prep 1-2h pre MRI with general anaesthesia/deep sedation | 6h solids/2h liq | Institution-specific

Patients with diabetes mellitus receiving insulin require special attention: fasting protocols must be coordinated with the treating endocrinologist or diabetologist to avoid hypoglycaemia. Blood glucose should be measured before the examination if fasting is required.

Water intake is generally encouraged in non-fasting patients scheduled for GBCA administration, as adequate hydration supports gadolinium renal clearance and reduces the theoretical risk of contrast nephropathy.

11. Medication Management

11.1 General Principles

Most medications should be continued as prescribed on the day of the MRI examination. There are no pharmacological interactions between standard medications and MRI electromagnetic fields. The relevant considerations are:

• Medications to be continued: Antihypertensives, antiepileptics, anticoagulants, thyroid medications, and most other chronic medications should be taken as usual. In fasting patients, medications may be taken with a small sip of water.

• Metformin: Although the risk of contrast-induced lactic acidosis with metformin is primarily established for iodinated contrast agents, some institutions apply similar precautionary hold guidelines to metformin in the context of GBCA-enhanced MRI in patients with renal impairment. Clinical judgement and institutional policy should guide this decision.

• Benzodiazepines or anxiolytics prescribed for MRI: These must be administered according to the prescribing physician's instructions, with appropriate monitoring during the examination and post-procedure discharge planning.

• Cardiac medications: For dedicated cardiac MRI examinations with stress protocols, specific medication restrictions apply and are detailed in the cardiac MRI-specific protocol.

12. Intravenous Access for Gadolinium-Based Contrast Administration

When GBCA administration is planned, intravenous access must be established prior to scanner entry. Standard peripheral venous cannulation with an appropriate gauge cannula (commonly 20-22 G for adults) is used. The choice of injection site should take into account the need for power injection where applicable: large calibre peripheral veins in the antecubital fossa or forearm are preferred.

The power injector-compatible cannula must be confirmed compatible with the planned injection rate; for dynamic contrast-enhanced sequences requiring rapid bolus injection (e.g., liver multiphasic, breast MRI, dynamic susceptibility contrast perfusion), injection rates of 2-5 mL/s are standard.

Extravasation risk must be assessed and managed. The incidence of GBCA extravasation is low (approximately 0.11% of injections), and most extravasations are mild and self- limiting; however, large extravasations into anatomically confined spaces (e.g., dorsum of the hand, orbit) may require intervention [1].

Patients with known difficult venous access should be flagged at the scheduling stage to allow for appropriate preparation (warm compresses, senior cannulation, or ultrasound- guided access).

13. Informed Consent and Patient Communication

13.1 Information Provision

All patients are entitled to receive clear, comprehensible information about the MRI procedure they are to undergo. This information should cover:

• The nature of the examination and its clinical purpose
• Duration and expected patient experience (noise, positioning, restricted movement)
• The emergency communication system (alarm squeeze device or verbal alert)
• Whether contrast will be administered, and if so, the associated risks
• Relevant preparation requirements (clothing, fasting if applicable, escort arrangement if sedation is planned)

Information should be provided in a format appropriate to the patient's language, literacy, and cognitive status. Pre-procedural information provision has been shown to reduce procedural anxiety and improve examination completion rates [8].

13.2 Consent for Contrast-Enhanced MRI

The standard for informed consent for GBCA administration varies by jurisdiction and institutional policy. In most settings, verbal consent following information provision is standard practice for routine GBCA administration in patients without significant contraindications. Written informed consent is required for:

• MRI with GBCA in pregnancy
• MRI with GBCA in patients with eGFR <30 mL/min/1.73 m2 when Group I agents are considered (Group II agents at all eGFR levels: the ACR states that informed consent prior to Group II GBCA injection is not recommended) [1]
• Research examinations

14. Special Populations: Summary of Additional Considerations

14.1 Paediatric Patients

Children generally require age-appropriate information and preparation strategies. Parental or guardian involvement is mandatory for patients below the age of consent. Young children often require sedation or general anaesthesia, triggering the full anaesthetic fasting and monitoring protocol (monitoring, personnel and equipment in the guidance read: Claustrophobia, Sedation, Monitoring, Equipment and Emergencies in the MR Environment, Sections 6 to 8). Specific considerations for paediatric body habitus (SAR management, RF coil sizing, patient immobilisation) are addressed in paediatric MRI protocols.

14.2 Patients with Reduced Mobility or Bariatric Patients

For patients with atypical habitus, including those with obesity, MRI safety evaluation requires particular attention to the assessment of bulk and focal heating by the radiofrequency field, as well as mechanical considerations related to patient positioning within the bore [2]. Table weight limits and bore aperture constraints must be verified before scheduling.

14.3 Patients with Communication or Cognitive Impairment

Patients who are unable to reliably complete the screening questionnaire, follow instructions during the examination, or operate the emergency alert device require tailored preparation, potentially including the use of sedation, the presence of a trained chaperone, or the use of alternative imaging modalities.

14.4 Detained Patients

In cases where a patient requires MRI while wearing RF-opaque metallic restraints (handcuffs, ankle cuffs), a request should be made that the patient be accompanied by the appropriate authorities who can and will remove the restraining device prior to the MR study and be charged with its replacement following the examination [1].

15. Documentation and Record-Keeping

Complete documentation of the pre-examination preparation process is both a safety and medicolegal requirement. Records should include:

• Completed MRI safety screening questionnaire (patient-completed and technologist- verified)
• Identity verification record
• Pregnancy status assessment for women of childbearing age
• Renal function results where GBCA administration is planned
• Allergy history and any premedication administered
• Consent documentation (verbal or written as appropriate)
• Record of all implants identified and their MRI safety status
• Name and signature of the MRI technologist who conducted the final screening verification

16. Emergency Preparedness in the MRI Environment

The statements of the guidance on equipment in the examination room, on removing the patient from the scan room, on the place and equipment of resuscitation, and on drills and training are in Claustrophobia, Sedation, Monitoring, Equipment and Emergencies in the MR Environment (Sections 8 and 9). Quench, venting and oxygen depletion are the subject of Cryogens, Quench and Oxygen Depletion in MRI.

Fatal and injurious projectile accidents with ferromagnetic oxygen cylinders and other equipment are documented; the incident evidence, the objects involved and the limits of that evidence are in Projectile and Torque Hazards in the Static Field [1,3].