Magnetic Resonance
Conditionality applications:
EU Requirements andsupporting Standards
A Regulatory Services position paper

Authors

By Royal Charter

Simon Lidgate Team Manager, AIMD
Gregory Griffin Technical Specialist, AIMD
Gregory Martin Technical Specialist, AIMD

BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

Contents

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BSI Active Implantable Medical Devices

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Overview

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Overview
An application for Magnetic Resonance (MR)conditionality adds new features to the device,along with new clinical benefits, and the potential
for new side effects and risks. Applications for
MR conditionality shall be evaluated for impact toall General Safety and Performance Requirements(GSPRs) of the EU Medical Devices Regulation(MDR) and must evaluate all benefits and risksof the device being scanned in MR. Evaluations
must be scientifically valid and be supported
by sufficient preclinical and clinical analysis.

4

Introduction

5

Requirements of the EU
Medical Devices Regulation

9

Application of Medical
Devices as MR Conditional
Introduction10
Consideration ofStandards and Guidelines

11

Establishment of requirements 12
Catagorization of device
hazards in the scanner

12

Design and validation of
MR scanning instructions

13

Assessment of risk

13

Clinical evaluation

14

15

Characterization of hazards
for Medical Devices in the
MR Environment
Introduction16
Static field related hazards

17Time-varying gradient
MF related hazards

18

RF field hazards

22

25

ConclusionDevices that are MR Conditional are thosefor which the clinical safety and performancehas been adequately demonstrated, in the
MR environment, under specific conditions ofscanning. Devices and MR Conditional information
provided to the clinician, technician, and endusers, must have been evaluated through preclinical and clinical evaluation such that it isproven the clinical benefit of the device with MR
Conditional labelling outweighs the additionalrisks, risks have been reduced as far as possible,
and that performance and safety are in line withthe generally acknowledged state-of-the-art.

Benefits and performances of the device
will include:
The ability to perform MR scans of target
areas to acquire images of meaningful
diagnostic quality
Correct and safe behaviour of the device
during and after an MR scanUndesirable characteristics of the device
present in the scanner may include:
Heat, forces, torques, and voltages createdby the device’s presence within the scanner
Unintended behaviour and/or malfunction of
the device in the vicinity of the scanner
Unintended interactions between the device
and other present (including implanted) devices,causing unintended behaviour of either device
Interference with the image acquisition, either
because of the device or because of restrictions
imposed on the scanning protocol, causing
artefacts and/or images of insufficient
diagnostic quality

BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

Risks of scanning may consequently include:
Risks of harm consequent of each of theundesirable characteristics exhibited duringlabelled scanning, i.e., seen even with proper
preparation and under conditions specified
within the IFU
Risks of harm consequent of undesirable
characteristics of the device in the scanner, if
the device is unintentionally scanned without
proper preparation, and/or under conditions
outside of those specified in the IFU
Risks of harm due to an incorrect or missed
diagnosis of conditions consequent ofartefacts or distortions to the image

4

As with all other aspects of the device,evaluations of risk should be supported
by evidence, such as:
Full characterization to applicable standardsof the device within the scannerTechnical evaluation validating usability ofthe scanning instructions, when used by theintended user
Full, scientifically-backed, clinical evaluation
to support the benefit of scanning and theacceptability of side effects and associatedrisks, including a full and ongoing comparison
to state-of-the-art
A plan to confirm benefits and risks of MR
Conditional labelling in the clinical environment
after certification
This paper provides an overview of these regulatory
requirements and the standards that support them.

Introduction
The European Medical Devices Regulation 2017/745 (MDR) dictates in Annex I general safety andperformance requirements (GSPRs) to which the manufacturer shall demonstrate compliance. In
particular, requirements to demonstrate the performance and safety of the device when subjected to
specified external environmental conditions are included.
To achieve this the regulations specify that
harmonised standards have a role in demonstrating
conformity. Article 8 indicates that harmonised
standards are those referenced in the Official
Journal of the European Union. In the absence ofa harmonised standard, or when the harmonised
version of the standard is superseded by alater version, it is expected that the latest
applicable standards are considered as partof the analysis against the state-of-the-art.
There are multiple relevant standards for medical
device behaviour and safety in an MR environmentthat have not been harmonised to the MDR at thetime of publication of this white paper.

In the absence of a harmonised standard, they may
be used to evaluate the completeness of device
characterization. In particular ISO/TS 10974:2018,
which at this time is still a technical specification
rather than a standard, and applicable only to 1.5T
closed bore MR scanners and Active Implantable
Medical Devices. With careful consideration however,it may act as a guide to help characterize the behaviourof a wide range of implantable and patient contacting
medical devices, in 1.5T closed bore and otherscanner types. Additionally, the next version of 10974,
whilst still focussing on AIMD, is to be a full standard
and is expected to expand its scope
to include 3T closed bore scanners.

BSI Active Implantable Medical Devices

Requirements of the EU
Medical Devices Regulation

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BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

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Some GSPRs, and their equivalent Essential Requirements (ER), that may be impacted by an MR Conditional
application are listed below. This list should not be considered exhaustive. The manufacturer shall performtheir own impact analysis to the GSPRs.

BSI Active Implantable Medical Devices

MDR GSPR
4.

MDR GSPR
1.

Devices shall achieve the performance
intended by their manufacturer and shall be
designed and manufactured in such a way
that, during normal conditions of use, they
are suitable for their intended purpose.
They shall be safe and effective and shallnot compromise the clinical conditionor the safety of patients, or the safety
and health of users or, where applicable,
other persons, provided that any risks
which may be associated with their use
constitute acceptable risks when weighedagainst the benefits to the patient and arecompatible with a high level of protectionof health and safety, considering thegenerally acknowledged state-of-the-art.

MDD ER: 1, 2, 3 | AIMDD ER: 1, 2, 3

Hover over each clause to see the remarks

3.

Manufacturers shall establish, implement,
document, and maintain a risk management
system. Risk management shall be
understood as a continuous iterative
process throughout the entire lifecycleof a device, requiring regular systematic
updating. In carrying out risk management
manufacturers shall:

Risk control measures adopted bymanufacturers for the design andmanufacture of the devices shall conformto safety principles, taking account of thegenerally acknowledged state-of-the-art.
To reduce risks, Manufacturers shall manage
risks so that the residual risk associatedwith each hazard as well as the overall
residual risk is judged acceptable.

Hover over each clause to see the remarks

6.

In selecting the most appropriate solutions,manufacturers shall, in the following orderof priority:

a Establish and document a risk
management plan for each device

a Eliminate or reduce risks asfar as possible
through safe design and manufactureb Identify and analyze the known andforeseeable hazards associated witheach device

b Where appropriate, take adequate
protection measures, including alarms,
if necessary, in relation to risks thatcannot be eliminatedc Estimate and evaluate the risks
associated with, and occurring during,the intended use and during reasonably
foreseeable misusec Provide information for safety (warnings,
precautions, contra-indications) andwhere appropriate, training to users
Manufacturers shall inform users of any
residual risksd Eliminate or control the risks referred
to in point (c) in accordance with therequirements of Section 4
e Evaluate the impact of information fromthe production phase and from the postmarket surveillance system, on hazards
and the frequency of occurrence thereof,on estimates of their associated risks,
as well as on the overall risk, benefit-riskratio and risk acceptability

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MDD ER: 2 | AIMDD ER: 6

5.

In eliminating or reducing risks related to use
error, the manufacturer shall:f Based on the evaluation of the impact of
the information referred to in point (e),if necessary, amend control measures inline with the requirements of Section 4b Consider the technical knowledge,
experience, education, training anduse environment, where applicable,
and the medical and physical conditionsof intended users (i.e., design for lay,professional, disabled, or other users)

MDD ER: - | AIMDD ER: -MDD ER: 4 | AIMDD ER: -The characteristics and performance of adevice shall not be adversely affected tosuch a degree that the health or safety of thepatient or the user and, where applicable, ofother persons are compromised during the
lifetime of the device, as indicated by the
manufacturer, when the device is subjectedto the stresses which can occur during
normal conditions of use and has been
properly maintained in accordance with the
manufacturer’s instructions.

MDD ER: 4 | AIMDD ER: 3
8.

All known and foreseeable risks, and any
undesirable side-effects, shall be minimized
and be acceptable when weighed against
the evaluated benefits to the patient and/or
user arising from achieved performance ofthe device during normal conditions of use

MDD ER: 6 | AIMDD ER: 5
14.2. Devices shall be designed and manufactured
in such a way as to remove or reduce as far
as possible:b Risks connected with reasonably
foreseeable external influences orenvironmental conditions, such as
magnetic fields, external electrical andelectromagnetic effects, electrostatic
discharge, radiation associated withdiagnostic or therapeutic procedures,pressure, humidity, temperature,
variations in pressure and acceleration
or radio signal interferences
f The risks of reciprocal interferencewith other devices normally used in theinvestigations or for the treatment given

MDD ER: 9.2 | AIMDD ER: 8

BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

MDR GSPR
17.2. For devices that incorporate software orfor software that are devices in themselves,the software shall be developed andmanufactured in accordance with thestate-of-the-art considering the principles
of development life cycle, risk management,
including information security, verificationand validation.
MDD ER: 12.1a | AIMDD ER: 9 (last indent)

23.1. General requirements regarding theinformation supplied by the manufacturer:
a The medium, format, content, legibility,
and location of the label and instructions
for use shall be appropriate to thedevice, its intended purpose and thetechnical knowledge, experience,education, or training of the intendeduser(s). Instructions for use shall be
written in terms readily understood by theintended user and, where appropriate,
supplemented with drawings and diagrams

Hover over each clause to see the remarks

23.4. Information in the instructions for use:g Any residual risks, contra-indications
undesirable side-effects, including
information to be conveyed to thepatient in this regard
k The information needed to verify
whether the device is properly installed
and is ready to perform safely andas intended by the manufacturers Information that allows the user and/or
patient to be informed of any warnings,
precautions, contra- indications, measures
to be taken and limitations of use regarding
the device. That information shall, where
relevant, allow the user to brief the patient
about any warnings, precautions, contraindications, measures to be taken andlimitations of use regarding the device
The information shall cover,where appropriate:f Instructions for use may be provided
to the user in non-paper format(e.g., electronic) to the extent, andonly under the conditions, set out inRegulation (EU) No 207/2012 or inany subsequent implementing rules
adopted pursuant to this Regulation

Warnings, precautions and/or measures
to be taken as regards the exposure toreasonably foreseeable external influences
or environmental conditions, such as
magnetic fields, external electrical andelectromagnetic effects, electrostatic
discharge, radiation associated withdiagnostic or therapeutic procedures,pressure, humidity, or temperature.

h Where appropriate, the information suppliedby the manufacturer shall take the form ofinternationally recognized symbols. Any
symbol or identification colour used shallconform to the harmonised standards
or CS. In areas for which no harmonised
standards or CS exist, the symbols
and colours shall be described in the
documentation supplied with the device

Warnings, precautions and/or
measures to be taken as regards therisks of interference posed by thereasonably foreseeable presence ofthe device during specific diagnostic
investigations, evaluations, or therapeutic
treatment or other procedures such as
electromagnetic interference emitted by
the device affecting other equipment.

MDD ER: 13.1 and 13.2 | AIMDD ER: 13 and 15
					(6th indent)

MDD ER: 2, 13.6(d), 13.6 (k-m) | AIMDD ER: 15
					(part 2)8

BSI Active Implantable Medical Devices

Application of Medical Devices
as MR Conditional

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BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

An application for MR conditionality shall therefore
be considered a significant design change fora device, as MR conditionality is a new device
feature with its own performances and risks.

BSI Active Implantable Medical Devices

Consideration of Standards and Guidelines

Introduction
The MR environment presents unique safety
hazards for patients and people with medical
devices near or inside an MR system. Ensuringsafety and performance for implants and otherdevices intended to enter an MR environment
should be an integral part of any application.

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MR conditionality has an impact on many
areas of the technical documentation and will
require ongoing evaluation in order to maintainexpectations set by the state-of-the-art.

Below is an example of standards and other documents that may be considered during an application
for MR conditionality. Please note that, at the time of publication, European standards listed are not yet
harmonised to the MDR. The manufacturer must ensure that, at the time of submission, compliance to thecurrent harmonised standards (or accepted state-of-the-art) and MDR is demonstrated.

This section provides examples of considerations
that may be made. It shall not be considered an
exhaustive list. The manufacturer shall performtheir own analyses.

ISO/TS 10974:20181

Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device

ASTM F2052

Standard test method for measurement of magnetically iinduced displacement
force on medical devices in the magnetic resonance environment

ASTM F21192

Standard test method for evaluation of MR image artefacts from passive implants

ASTM F2182

Standard test method for measurement of radio frequency induced heating onor near passive implants during magnetic resonance imaging

ASTM F2213

Standard test method for measurement of magnetically induced torque on
medical devices in the magnetic resonance environment

ASTM F2503

Standard practice for marking medical devices and other items for safety inthe magnetic resonance environment

EN ISO 14971:2019

Medical devices - Application of risk management to medical devices

EN 62366:2008(EN 62366-1:2015)

Medical devices - Application of usability engineering to medical devices

EN 60601-2-33:2010 Particular requirements for the basic safety and essential performance of+A12:2016
magnetic resonance equipment for medical diagnosis
MEDDEV 2.7.1 Rev.43

Clinical evaluation: a guide for manufacturers and notified bodies under
directives 93/42/EEC and 90/385/EEC

FDA-2019-D-2834

Testing and Labeling Medical Devices for Safety in the Magnetic Resonance (MR)
Environment, Guidance for Industry and Food and Drug Administration Staff, MAY 2021

NOTE 1: As of the date of the issuance of this guidance, ISO/TS 10974 contained extensive information addressing the introductionof active implantable medical devices (AIMDs) into the 1.5T MR environment. While the scope is currently limited, it contains detailed
information about hazards for medical devices in the MR environment and methods for assessing specific hazards that may be
applicable for other types of medical devices.
NOTE 2: This standard has been withdrawn and there is no replacement at the time of publication of this white paper. It therefore
no longer represents the state of the art in artefact characterisation. The manufacturer will need to carefully consider any replacement
standard, and/or how to characterise image artefacts surrounding the medical device most effectively.
NOTE 3: The guidance MEDDEV 2.7.1 Rev. 4 is superseded in parts by the requirements of the MDR. Please refer to Appendix I of
MDCG 2020-6 for guidance as to relevant parts.

NOTE 4: Whilst this is not a European standard or guidance, and may contain some irrelevant information, the FDA guidance on MR
testing may still provide some additional valuable guidance on how to evaluate a medical device for safety in the MR environment.

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Establishment of requirements
As with all design aspects, requirements should be set around clinical needs and safety and performance,and considering the state-of-the-art: i.e., establishment and consideration of the generally acknowledged
state-of-the-art, MR Conditional parameters of other devices, accompanying guidance etc.

SAFETY

Heating, forces, torques, induced voltages, etc. that may be tolerated by thepatient without discomfort or injury, in all conditions the patient may be scannedin, including the possibility of a raised temperature, impaired physiological state
impacting safety thresholds or thermoregulation, or immediately after surgery

PERFORMANCE

Modes and functionality required of the device during the scan. Diagnostic
image requirements and acceptable limitations that will ensure that the benefit
outweighs the risk

CONDITIONSOF SCANNING

Types of scanners, tesla strengths, coil types, magnetic gradients, slew rates,
SAR (and B1+rms), patient positioning, scan times, pre and post conditioning
conditions, and any other conditions required for the safe scanning with thedevice in situ, to get the diagnostic images required

Characterization of device hazards in the scannerConsidering ISO/TS 10974:2018, ASTM F2052, ASTM F2119, ASTM F2182, ASTM F2213:
Establishment of expected device behaviour within the scanner, and a clear analysis of which tests
are required and which test method is most appropriate for the device (e.g., with RF heating, several
different test methods are available)
Testing of a device to the appropriate standards and establishing worst-case device behaviour in
MR conditions in all relevant device states
Establishment of conditions under which the device may be scanned, whilst still meeting safety
requirements
The next section outlines the different hazards that may present themselves within a scanner.

BSI Active Implantable Medical Devices

Design and validation of MR scanning instructions
ISO/TS 10974:2018

Assessment of the safety of magnetic resonance imaging for patients with anactive implantable medical device, Clause 18, Markings and accompanying
documentation

EN 62366:2008(EN 62366-1:2015)

Medical devices - Application of usability engineering to medical devices

Considering the requirements of MDR and all relevant standards:
Design of the IFU in compliance to applicable standards, providing clear information
Clear reporting of all identified residual risks applicable to MR conditionality
Clear conveyance of limitations of image quality/location that will be achieved consequent of thedevice in situ
Validation of all steps required to perform a safe scan, for instance via a usability study compliant toISO 62366, including:• Correct preparation of the device for scanning• Understanding conditions and taking all precautions necessary during scanning• Confirm availability of IFU to MR scanning centres and clinicians and how it is made available

Confirm implant card, e.g., provides information to allow implanted device and accessories to be
identified and scanned correctly
Confirm MR Conditional labelling is correctly applied and MR Unsafe labelling applied where
accessories to the device have not been shown to be safe under MR conditions

Assessment of risk
ISO 14971:2019

Medical devices. Application of risk management to medical devices

Considering all evidence available, risks are mitigated AFAP via design, and ensuring residual risks are
identified and appropriately reported:
Risks associated with scanning according to conditions
Risks associated with scanning off label, where certain aspects of the conditions of scanning aremisinterpreted or ignored

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Clinical evaluation
MDR Annex XIV

Clinical evaluation and post-market clinical follow-up

MEDDEV 2.7.1 Rev 4

Clinical evaluation: a guide for manufacturers and Notified Bodies under
directives 93/42/EEC and 90/385/EEC

MDCG 2020-6

Clinical evidence needed for medical devices previously CE marked underDirectives 93/42/EEC or 90/385/EEC A guide for manufacturers and NotifiedBodiesClinical evaluation of clinical risks and benefits of scanning the device including:
Evaluation of scanning conditions against current state-of-the-art
Evaluation of device characteristics within the scanner, and potential risks to the patient
Evaluation of quality of imaging achievable with device in situ
Acceptability of residual risks given benefit of MR Conditional labelling
A plan to maintain current knowledge of the state-of-the-art in regard to MR, e.g., with an appropriate
protocol to capture literature on state-of-the-art devices’ behaviour in MR.
A plan to maintain current knowledge of the subject device, e.g., with an appropriate protocol to capture
literature on the subject device and equivalents’ behaviour in MR.
An appropriate PMCF plan to close gaps in clinical knowledge of the subject device, i.e., to collectsufficient clinical evidence to confirm device performance and safety in the MR environment.

BSI Active Implantable Medical Devices

Characterization of hazards
for Medical Devices in the
MR Environment

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BSI Active Implantable Medical Devices

Introduction

Static field related hazards

Standards considered may include ISO/TS 10974:2018, ASTM F2052, ASTM F2119, ASTM F2182,
ASTM F2213.

The principal field of the MR scanner is a strong,magnetic field in the order of several Tesla. They
can be permanent magnets or electromagnets witheither standard, or superconducting coils. Thesecan be in an open or closed bore configuration,i.e., the sides of the scanner may be open with themagnet above and below the patient or the patient
may be inserted into the closed cylindrical bore of
the magnet via a table. Except for the electromagnet
with a standard coil, the static magnetic field isalways present. It should be assumed with all
systems that this is the case, as where it is possible
with the standard coil electromagnet to switch
the field off, it is not in practice done often as it
can take ½ hour or longer to achieve a field stableenough to scan, when it is switched back on.

The scanner “environment” includes threeprincipal fields:
1. A high tesla “B0” static magnetic field, which
for most scanners is always-on. This meansthat the hazards related to this field are always
present. Typical horizontal closed bore scanners
most commonly exhibit tesla strengths of
1.5 or 3 Tesla. As well as field strength, themaximum spatial field gradient (how quickly
the magnetic field drops off with distancefrom the scanner) is an important factor andcan be up to 20 T/m in a 1.5 Tesla scanner.
2. A high-speed time varying gradient magnetic
field, switching in the order of 100’s of Hz,
present transiently during the scan. Maximum
slew rate, measured in Tesla / Metre / Second,is an important variable, along with switchingfrequency. The maximum slew rate seen
in modern scanners is around 200 T/m/s
per axis. The slew rate is used along with
the implant radial position, to calculate theworst-case rate of change of the magnetic
field (dB/dt) at the implant location.
3. An RF electromagnetic field in the range ofmegahertz (frequency is proportional to thestrength of the static magnetic field ~64MHz
in a 1.5T scanner, ~128MHz in a 3T scanner).
Historically RF field strength is normallymeasured in relation to average power
absorption density in the body (SpecificAbsorption Rate: SAR) and is typically limited
to 2W/kg whole-body SAR (wbSAR) and
3.2 W/kg head SAR (hSAR) in Normal
operating mode, but can reach up to 4W/kg
in First Level Controlled operating mode.
B1+rms is a newer parameter used to characterize
average RF field strength more directly.

This section summarizes the main ways the scanner
environment can impact the device causing undesirable
effects that consequently impact the patient thedevice is in contact with or implanted inside.
All aspects shall be considered, for all types ofscanners intended to be included in the labelling.
Results are not automatically transferrable between
scanner types due to each scanner type presenting
a unique combination of fields. Additionally, scannerproperties vary between manufacturer and generation.
It is important that any variations are taken into
account when considering each aspect.
Multiple tests to characterize a property are available.
One or other may be more, generally suitable fordifferent types of medical devices or where theperceived risk is higher or lower. Some tests sacrificeaccuracy for ease of implementation and overestimate
the property. Some tests are more accurate, at a costto complexity and the consequent possibility thatincorrect implementation may invalidate the result.
Clear rationales for the selection and types of testing
performed are required. Testing may not be required
if an adequate scientific rationale is provided in thecase where there will clearly be no impact.
It should be noted that testing provides acharacterization of device behaviour but do noton their own provide proof of device safety in thescanner. The manufacturer is required to perform afull analysis, as exampled in the previous section
to justify any claims of safety and performance.

In general, open bore scanners are of lower Tesla
strengths and closed bore scanners are of higher
strengths. A higher Tesla, closed bore scanner canacquire higher quality images in equivalent scantime. Open bore scanners, on the other hand,
may be preferable for particular scan types, may
aid accessibility and may be suitable for somepaediatric patients, or patients who suffer from17

claustrophobia. The most common scanner typethat is considered for MR conditionality is the 1.5T,
closed bore, superconducting coil scanners, with
3T closed bore scanners becoming more popularin clinics in recent years. High Tesla magnetic fields
can impose significant torques on a medical device.
In addition to the strength of the static magnetic
field, the spatial gradient of the static magnetic
field is a key MR scanner characteristic that varies
between scanner type, manufacturer and modeland that principally determines the magnitudeof the force exerted on a device. In modern
scanners the spatial gradient is in the order of
T/m, and typically is at a maximum near thescanner, just outside of the bore of the scanner.
Forces and torques imposed on a device may cause
direct mechanical harm to the patient. Forces andtorques on device components can cause medical
devices to malfunction.
The manufacturer is expected to evaluate the effectof the static field on their device as follows.

BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

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Force

ISO/TS 10974:2018

ASTM F2052

BSI Active Implantable Medical Devices

TorqueAssessment of the safety of magnetic resonance imaging for patients with anactive implantable medical device, Clause 11, protection from harm to the patientcaused by B0-induced force

ISO/TS 10974:2018

Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device, Clause 12 Protection from harm to thepatient caused by B0-induced torque

Clause 11 does not provide significantly more information and guides the reader
to ASTM F2052.

Clause 12 does not provide significantly more information and guides the reader
to ASTM F2113.

Standard Test Method for Measurement of Magnetically Induced Displacement
Force on Medical Devices in the Magnetic Resonance Environment

Standard Test Method for Measurement of Magnetically Induced Torque on
Medical Devices in the Magnetic Resonance Environment

Provides a method by which the force exerted on a device due to the magnetic
field can be measured. However, it is only useful for devices where the exerted
force is in the same order of the device weight or less. If much greater forces areexerted, then the test may need to be modified. The manufacturer is responsible
for justifying any changes to the test method. The manufacturer shall relate themeasured force to the maximum likely experienced force in a scanner via an
appropriate and justified method.

Provides methods by which torque may be measured. The Manufacturer is
responsible for justifying the method chosen.

Provides an assumption, not an acceptance criterion, that the risk imposed for
a force less than the force of gravity, would not be any greater. For any maximum
likely force predicted, the manufacturer must provide a scientifically and clinicallybacked justification of acceptability, considering all possible clinical conditions of
the patient.

ASTM F2213

Provides an assumption, not an acceptance criterion, that the risk for a torqueless than that imposed by gravity, would not be any greater. For the maximum
torque predicted, the manufacturer must provide a scientifically and clinicallybacked justification, considering all possible clinical conditions of the patient.

ImpactTorque occurs principally where the magnetic field is strongest, nominally at the centre of the bore of themagnet. Torque occurs as magnetic components attempt to align with field contours. This torque may
cause pressure on the patient’s tissue, or cause displacement of the device itself, injuring the patient
and/or affecting device function.

ImpactBoth the magnetic field and its gradient induce forces on magnetic materials. This force may cause pressure
on the patient’s tissue, or cause displacement of the device itself, injuring the patient and/or affecting
device function.

Device malfunction
ISO/TS 10974:2018

Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device. Clause 14 Protection from harm to thepatient caused by B0-induced malfunction.

ImpactDevice malfunction due to interaction with magnetic fields is observed in both active and passive medical
devices and is possible in cases where ferromagnetic, or magnetic, components make up part of thedevice, as well as any electronic components that are sensitive to magnetic fields. ISO/TS 10974:2018provides some guidance for AIMDs which is of limited relevance to non-active devices. Manufacturers are
expected to evaluate the possibility of device failure because of static magnetic field or provide a clear
scientific justification why no failure can be expected.

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Time-varying gradient magnetic field related hazards
During the scan, on top of the static magnetic fieldis generated a magnetic gradient that switches in
the order of several hundred Hz to kHz. This timevarying magnetic field can induce currents in wires,
coils and metallic plates of significant surface area.
These currents can cause heating of the device,
vibrations, or unintended stimulation of the patient.
In general, the magnetic field varies greatest andfastest towards the edges of the scanner. It may
be possible to position the device to minimize theeffect of the field on the device at the cost of more
complex instructions, and the risk thatthey are not properly followed.

ISO/TS 10974:2018 considers the effects of thetime-varying gradient magnetic field on AIMDs, butsome aspects are also relevant to other devices.
In the absence of a more relevant standard, themanufacturer should consider the tests in ISO/TS
10974:2018 to characterize the behaviour of devices
due to the time-varying gradient magnetic field.
The manufacturer is expected to evaluate the effectof the time-varying gradient magnetic field on theirdevice in the following areas.

BSI Active Implantable Medical Devices

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Device vibration and malfunction

ISO/TS 10974:2018

Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device. Clause 10 Protection from harm to thepatient caused by gradient-induced vibration
Provides two methods by which a device may be tested for vibration, via direct
testing within the scanner, or via a shaker table mimicking vibrations observed
within the scanner.

ImpactDevices prone to eddy currents, e.g., devices with large metallic surfaces, may also be prone to vibration in
the scanner. This is due to an interaction with the magnetic field generated by eddy currents and the static
magnetic field. This vibration will be in the order of 100’s of Hz, at the same speed of the switching coil, andas such is different in nature to vibrations experienced in transportation.
Vibration may cause a patient injury if it causes the device to malfunction and/or if the device is in contact
with sensitive membranes or organs of the patient.
The manufacturer is expected to consider Device vibration in the overall evaluation of the device for
MR Conditionality.

Device heating
Assessment of the safety of magnetic resonance imaging for patients with anactive implantable medical device. Clause 9 Protection from harm to the patientcaused by gradient-induced device heating
ISO/TS 10974:2018

Provides formulae to estimate deposition of power in devices with a significant
surface area, and estimations as to where the greatest heating may be observed
within a scanner. This clause also provides tiered tests of varying complexity toestablish likely heating observed within MR.

Unintended stimulation

ISO/TS 10974:2018
ImpactSwitching gradient magnetic fields will induce eddy currents in conductive enclosures, coils or devices witha significant conductive surface area. Examples of this may be enclosures of a pacemaker or implanted drug
infusion pump, metallic meshes and other orthopaedic implants. Eddy currents will in turn cause heating of thedevice. Excessive heating when in contact with sensitive tissues may cause patient injury.
The manufacturer is expected to consider device heating due to eddy currents in the overall evaluation of
the device for MR conditionality. In cases where heating is likely, the manufacturer should perform analyses
to establish the extent of any heating. If no testing is deemed necessary, justifications mustbe supplied.

Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device, Clause 13, Protection from harm to thepatient caused by gradient-induced extrinsic electric potential
Clause 13 provides the theory and testing requirements for devices that may
be prone to unintended stimulation.

Impact
Unintended stimulation is a phenomenon only likely to be seen in AIMDs or Active Devices in contact withthe patient (and intended to provide electrical energy to the patient in normal operation). Unintended
stimulation occurs typically with the combination of an electrode in contact with the patient and attached
to a coil and/or nonlinear electric circuit.
The manufacturer is expected to consider unintended stimulation due to the Time Varying Gradient Magnetic
Field in the overall evaluation of the device for MR conditionality. In cases where unintended stimulation ispossible, the manufacturer should perform analyses to establish the extent, considering ISO/TS 10974:2018
in the absence of more relevant standards. If no testing is deemed necessary, a justification must be
provided.

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RF field hazards
The RF field is used to excite nuclei (typicallyhydrogen) during MR scans; the energy returned
later in the form of a signal which is read to generate
the MR image. The RF field is either generated andread via a Transmit/Receive (T/R) “body” coil which
is surrounding the patient in the scanner itself, or itis delivered and/or read via various types of “local”
coils designed to focus the RF signal onto the volume
of interest. The frequency of the RF field is directly
proportional to the strength of the static field. For
1.5T hydrogen imaging the frequency is nominally64MHz, for 3T scanners around 128MHz.
There are several methods by which the device
RF exposure may be limited, which includes thelimitation of the SAR of the scan, usage of local T/Rcoils, or limiting scans to parts of the body.
However, this comes at a cost of reduced
performance i.e., reduced quality of imaging, andareas where imaging is impossible (e.g., aroundthe device itself) and increased risk, i.e., increased
complexity of instructions, and the risk that
instructions may not be properly followed.

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RF heating
RF effects are particularly complex to evaluate. At every
stage there must be careful review and justification of
methods chosen and assumptions made.

ASTM F2182

To know more on testing methods refer to:
ASTM F2182 - provides testing methods toevaluate RF heating for passive devices, however
the methods are limited and may not be suitable
for all devices
ISO/TS 10974:2018 - Provides several types oftests for heating, unintended stimulation, anddevice malfunction, that may be used to evaluate
both passive or active devices. Tests vary incomplexity, required computational resource,
and accuracy.

ISO/TS 10974:2018

Standard Test Method for Measurement of Radio Frequency Induced Heating
on or Near Passive Implants During Magnetic Resonance Imaging
Provides testing methods to evaluate RF heating for passive devices; however
the methods are limited and are not suitable for all devices.
Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device, Clause 8, Protection from harm to thepatient caused by RF-induced heating
Clause 8 provides several types of test for heating that may be used to evaluate
both passive or active devices. The test range in complexity, the intensity ofresource, and accuracy.

ImpactAny conductive structure may act as an antenna and hence absorb or focus the RF energy in small volumesof tissue, causing excessive heating. This heating, which happens for instance around tips of leads or ends
of metallic structures such as screws, vascular stents, or orthopaedic implants, may damage the surrounding
tissue, especially if the device is in contact with sensitive structures. The consequence may be patient injury
including mental or physical impairment, or the reduction of efficacy of therapy in the case of Active Implantablestimulation devices. The behaviour is dependent on RF frequency, and so characterizations performed at one
frequency do not mean that assumptions of similar performance can be made at other frequencies.
It, therefore, is not generally accepted that tests performed for one type of scanner are applicable to another.
Additionally, if devices are commonly implanted with other devices, or multiples of the same device used,then there may be interaction at the RF scale that increase the hazard.
The manufacturer is expected to consider the potential for RF heating with their device and to carefully
evaluate any potential mitigations required to keep RF heating to an acceptable level. If mitigation isrequired, risk benefit and usability analyses shall be performed, and clinical follow-up proposed where itis necessary to confirm the efficacy of mitigations. If no testing is deemed necessary, justifications must
be provided.

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Unintended stimulation
Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device, Clause 15, Protection from harm to thepatient caused by RF-induced malfunction and RF rectification
ISO/TS 10974:2018

Provides a table to identify situations where stimulation or malfunction are likely,
and three different methods by which unintended stimulation and device
malfunction may be evaluated, and provides detailed tests by which device
behaviour under RF may be characterized.

ImpactRF unintended stimulation is only likely to be observed with active devices with electrodes and electronicsystems. Unintended stimulation and device malfunction may lead to inappropriate or lack of therapy, which
may have severe consequences for the patient’s physical health.
RF Device Malfunction is only likely to be observed within active devices with electronic systems, or passive
devices with parts that are sensitive to the temperature rise caused by RF heating.
The manufacturer is expected to consider the potential for RF unintended stimulation or malfunction with
their device, evaluate under worst case conditions, and to carefully evaluate any potential mitigations
required to keep risk to an acceptable level. In the case that mitigation is required, risk benefit and usability
analyses shall be performed, and clinical follow-up is proposed where it is necessary to confirm the efficacyof mitigations. If no testing is deemed necessary, justifications must be provided.

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Image Artefacts

ASTM F2119

Standard Test Method for Evaluation of MR Image Artefacts from Passive
Implants. Provides some methods by which the extent of artefacts may bequantified. Please note that this standard has now been withdrawn with no
replacement at the time of publication of this white paper. It therefore cannot
be considered a comprehensive guidance to evaluate artefacts, and additional
considerations may need to be made to comprehensively characterise image
artefacts caused by the device.

ISO/TS 10974:2018

Assessment of the safety of magnetic resonance imaging for patients withan active implantable medical device. Clause 18 Markings and accompanying
documentation.

Impact
The performance of the scanner is affected by the presence of the device.
Devices in place when the patient is scanned may affect the quality of the captured image around the device.
Artefacts in the image may hide or distort features of interest, and may affect the diagnostic quality of theimage, in extreme cases to the point it becomes unusable.
It should be made clear within the IFU the geometric extent of artefacts, and under which conditions. For
instance, if the electrodes of the spinal cord scanner generate artefacts that occlude the spinal column, thisshould be made clear within the IFU.
Device MR performance may be improved by providing methods by which the artefact may be minimized anda useful diagnostic image obtained.

BSI Magnetic Resonance Conditionality Applications - EU Requirements and Supporting Standards

Conclusion
Labelling a medical device as MR conditional is achange in conditions of use and, as such, has awide-ranging impact to many aspects of the MDR
Technical Documentation. The areas impacted will
include Risk, V&V, Usability, Labelling, andClinical Evaluation.
This position paper has attempted to highlight thebreadth of the impact by providing an overview ofaspects to consider prior to an application of MR
conditionality for a medical device. It does not aim
to be comprehensive. Additionally not all aspects
discussed may be relevant to all medical devices
on which MR conditional labelling may be applied.
No presumption of conformity can be made byfollowing the considerations in this paper.

Further reading
The reader should refer to the regulations,standards, and guidance mentioned throughout
this position paper for more information.

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with reliance on its contents except to the extent that such liability may not be excluded in law.

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