AAMI TIR10974 2018
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AAMI/ISO TIR10974:2018 – Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device.
| Published By | Publication Date | Number of Pages |
| AAMI | 2018 | 232 |
Applies to implantable parts of active implantable medical devices (AIMDs) intended to be used in patients who undergo a magnetic resonance scan in 1,5 T, cylindrical (circular or elliptical crosssection) bore, whole body MR scanners operating at approximately 64 MHz with whole body coil excitation. The tests that are specified in this document are type tests that characterize interactions with the magnetic and electromagnetic fields associated with an MR scanner. The tests can be used to demonstrate device operation according to its MR Conditional labelling. The tests are not intended to be used for the routine testing of manufactured products.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | AAMI/ISO TIR10974:2018; Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device |
| 3 | Title page |
| 4 | Copyright information |
| 5 | AAMI Technical Information Report ANSI Registration |
| 6 | Contents Page |
| 10 | Glossary of equivalent standards |
| 11 | Committee representation |
| 12 | Background of the AAMI adoption of ISO TS 10974:2018 |
| 13 | Foreword |
| 14 | Introduction |
| 19 | 1 Scope 2 Normative references |
| 20 | 3 Terms and definitions |
| 25 | 4 Symbols and abbreviated terms 5 General requirements for non-implantable parts 6 Requirements for particular AIMDs 7 General considerations for application of the tests of this document 7.1 Compliance criteria 7.2 Use of tiers |
| 26 | 7.3 Test reports 7.3.1 General 7.3.2 Description of the AIMD under test 7.3.3 Test methods and results 8 Protection from harm to the patient caused by RF-induced heating 8.1 Introduction |
| 27 | 8.2 Outline of the Stage 1 four-tier approach |
| 28 | 8.3 Measurement system prerequisites for all tiers 8.3.1 RF field source |
| 29 | 8.3.2 Tissue simulating phantom |
| 30 | 8.3.3 Definition of power deposition 8.3.4 Measurement system validation 8.4 Determination of RF-induced power deposition in a tissue simulating medium 8.4.1 General |
| 31 | 8.4.2 Determine location of hot spots around the AIMD 8.4.3 Determination of spatial (3D) distribution of power deposition for each hot spot 8.4.3.1 General 8.4.3.2 Procedure 1: Numerical assessment with thermal validation |
| 32 | 8.4.3.3 Procedure 2: Numerical assessment with SAR validation 8.4.3.4 Procedure 3: Full 3D SAR measurements 8.4.3.5 Procedure 4: Full 3D ΔT measurements 8.4.4 Determine the final power deposition 8.4.4.1 General 8.4.4.2 Procedure 1: Temperature increase ΔT (if using Procedure 4 from 8.4.3) |
| 33 | 8.4.4.3 Procedure 2: SAR (if using Procedure 1, Procedure 2, or Procedure 3 from 8.4.3) 8.4.4.4 Procedure 3: Calibration of point temperature or SAR measurements to total dissipated RF power 8.5 Proximity effect of electrodes from multiple leads |
| 34 | 8.6 Modelling prerequisites for Tier 2, Tier 3, and Tier 4 8.7 Tier selection for RF-induced power deposition 8.7.1 General |
| 35 | 8.7.2 Tier 1 |
| 36 | 8.7.3 Tier 2 8.7.4 Tier 3 |
| 37 | 8.7.5 Tier 4 |
| 38 | 8.8 In vitro model validation |
| 40 | 8.9 Overall uncertainty analysis 8.10 In vivo analysis of power deposition 8.11 RF-induced heating assessment flow chart |
| 44 | 9 Protection from harm to the patient caused by gradient-induced device heating 9.1 Introduction |
| 45 | 9.2 Testing considerations 9.2.1 General 9.2.2 Determination of |dB/dt| rms exposure limits 9.2.3 Determination of test duration |
| 46 | 9.3 Test requirements 9.3.1 General 9.3.2 In vitro test phantom or other suitable container |
| 47 | 9.3.3 Gelled solution 9.3.4 Temperature survey to determine orientation and hot spots 9.3.5 Minimum temperature instrumentation 9.3.6 Definition of dB/dt test waveform 9.3.6.1 General 9.3.6.2 Tier 1 |
| 48 | 9.3.6.3 Tier 2 9.3.7 Characterization of applied dB/dt 9.4 Lab testing using simulated MR gradient field |
| 49 | 9.5 MR scanner testing 9.6 Analysis of gradient heating test 10 Protection from harm to the patient caused by gradient-induced vibration 10.1 Introduction |
| 50 | 10.2 Overview of tiers |
| 51 | 10.3 MR environmental conditions 10.3.1 General 10.3.2 Determination of maximum clinical dB/dt 10.3.3 Determination of clinical B0 10.3.4 Determination of clinical dB/dt × B0 10.3.5 Test frequencies 10.3.5.1 General |
| 52 | 10.3.5.2 Using a clinical MR scan sequence 10.3.5.3 Using an arbitrary gradient waveform 10.3.6 Test duration 10.3.7 Test temperature 10.3.7.1 General |
| 53 | 10.3.7.2 Room temperature 10.3.7.3 Body temperature 10.4 General test procedure 10.4.1 Measurement of gradient field and determination of AIMD location 10.4.2 AIMD/test unit setup 10.4.2.1 Orientation of AIMD in scanner |
| 54 | 10.4.2.2 Mounting 10.5 Method 1 — MR scanner |
| 55 | 10.6 Method 2 — Shaker table 10.6.1 General 10.6.2 Determine scanner input 10.6.3 AIMD vibration response 10.6.3.1 Measurement equipment |
| 56 | 10.6.3.2 Measure the AIMD vibration response 10.6.4 Determine shaker table amplitude (dB/dt scaling) 10.6.5 Perform vibration exposure using a shaker table 10.6.5.1 General 10.6.5.2 Random vibration 10.6.5.3 Profile-driven vibration |
| 57 | 11 Protection from harm to the patient caused by B0-induced force 12 Protection from harm to the patient caused by B0-induced torque 13 Protection from harm to the patient caused by gradient-induced extrinsic electric potential 13.1 Introduction |
| 59 | 13.2 General requirements |
| 62 | 13.3 Gradient pulse leakage test 13.3.1 General 13.3.2 Test equipment 13.3.3 Test signal |
| 64 | 13.3.4 Tier 1 — Combined gradient-induced charge measurement test procedure |
| 67 | 13.3.5 Tier 2 — Separate transient gradient-induced charge and steady-state current measurement test procedure 13.3.5.1 Gradient-induced charge measurement test procedure 13.3.5.2 Gradient-induced current measurement test procedure |
| 69 | 13.4 Gradient rectification test 13.4.1 General 13.4.2 Test equipment 13.4.3 Test signal |
| 70 | 13.4.4 Gradient-induced rectification measurement test procedure |
| 71 | 13.5 Gradient pulse distortion of AIMD output test 13.5.1 General |
| 72 | 13.5.2 Test equipment 13.5.3 Test signal 13.5.4 Gradient-induced AIMD output distortion test procedure |
| 74 | 14 Protection from harm to the patient caused by B0-induced malfunction 14.1 Introduction |
| 75 | 14.2 Static field testing 14.2.1 B0 general requirements for static field testing 14.2.2 B0 field generation |
| 76 | 14.2.3 Test conditions 14.3 Test procedures 14.3.1 General 14.3.2 Class 0 test procedure 14.3.3 Class 1 test procedure 14.3.4 Class 2 test procedure |
| 77 | 15 Protection from harm to the patient caused by RF-induced malfunction and RF rectification 15.1 Introduction 15.2 General requirements 15.3 Mechanisms for RF interaction with an AIMD |
| 79 | 15.4 Selecting radiated vs injected test methods 15.4.1 General 15.4.2 AIMD type designation for test method selection |
| 80 | 15.4.3 RF antenna type designation for test method selection |
| 81 | 15.4.4 RF EMC tier selection 15.4.5 RF test conditions |
| 84 | 15.4.6 B0 considerations 15.5 Injected immunity test 15.5.1 General |
| 85 | 15.5.2 Determination of peak and rms injected levels for Tier 1 and Tier 2 — AIMD with short electrical length 15.5.3 Determination of peak and rms injected levels for Tier 3 and Tier 4 |
| 87 | 15.5.4 Injected immunity test procedure 15.5.5 RF phase test conditions |
| 88 | 15.5.6 AIMD monitoring during the test 15.6 Radiated immunity test 15.6.1 General 15.6.2 Determining the RF radiated field level 15.6.3 Radiated test procedure 15.6.4 AIMD monitoring during the test 15.7 Test equipment 15.7.1 Generating the RF electric field for radiated testing (AIMD with short electrical length) |
| 89 | 15.7.2 Phantom and tissue simulating medium for radiated testing 15.7.3 AIMD monitoring apparatus 15.7.4 RF level measuring device |
| 90 | 15.7.5 RF injection network 15.8 Determining the peak RF injected level using a radiated test |
| 92 | 16 Protection from harm to the patient caused by gradient-induced malfunction 16.1 Introduction 16.2 General requirements 16.3 Selecting radiated and injected test methods |
| 93 | 16.4 Radiated immunity test 16.4.1 General |
| 94 | 16.4.2 Test equipment |
| 96 | 16.4.3 Radiated test signal |
| 98 | 16.4.4 Test procedure |
| 99 | 16.5 Injected immunity test 16.5.1 General 16.5.2 Test equipment 16.5.3 Injected test signal |
| 100 | 16.5.4 Test procedure |
| 102 | 16.5.5 AIMD test configuration 16.5.5.1 General 16.5.5.2 Group a) |
| 105 | 16.5.5.3 Group b) |
| 108 | 16.5.5.4 Tissue interface network |
| 110 | 17 Combined fields test 17.1 Introduction 17.2 Test setup |
| 114 | 17.3 AIMD fixation 17.4 Test procedure 17.4.1 General 17.4.2 Before MR exposure 17.4.3 During MR exposure 17.4.4 After MR exposure 17.5 Test equipment 17.5.1 Field generation 17.5.2 Phantom and tissue simulating medium |
| 115 | 17.5.3 AIMD monitoring apparatus 18 Markings and accompanying documentation 18.1 Definitions 18.2 Applicability of labelling requirements 18.3 Labelling requirements |
| 117 | Annex A (normative) Pulsed gradient exposure for Clause 10, Clause 13, and Clause 16 A.1 Pulsed gradient exposure for Clauses 10, 13, and 16 A.2 Determination of dB/dt for AIMD electronics module, electrodes, and extended leads A.2.1 AIMD labelled for Fixed Parameter Option |
| 118 | A.2.2 AIMD labelled for maximum gradient slew rate |
| 122 | A.3 Injected voltage determination A.3.1 General A.3.2 Tier 1, Lead length multiplication factor method |
| 124 | A.3.3 Tier 2, Specific AIMD lead loop area method |
| 126 | A.3.4 Tier 3, Electromagnetic simulation method |
| 128 | A.3.5 Model validation for Tier 3 |
| 130 | Annex B (informative) Derivation of lead length factor for injected voltage test levels for Clause 13 and Clause 16 |
| 138 | Annex C (informative) Tier 1 high tangential E-field trough line resonator C.1 Background C.2 Design Example |
| 142 | C.3 Performance |
| 145 | Annex D (informative) Supporting information and rationale for gradient-induced device heating D.1 Rationale for gradient heating |dB/dt| rms D.1.1 General D.1.2 Data survey of clinical MR scanners |
| 147 | D.1.3 Determination of clinical dB/dt exposure limits |
| 148 | D.2 Gradient heating Tier 1 waveform rationale D.2.1 General D.2.2 Waveform type D.2.3 Magnitude of |dB/dt| rms D.2.4 Magnitude of BG D.2.5 Waveform frequency |
| 150 | Annex E (informative) Example RF injection network |
| 152 | Annex F (informative) Supporting information and rationale for MR-induced vibration F.1 Explanation of MR-induced vibration |
| 153 | F.2 Tiers: MR scanner vs shaker table F.3 Clinical scanner vs research scanner F.4 Potential for AIMD resonance |
| 154 | F.5 Supporting rationales F.5.1 Gradient switch mode noise (“Ripple”) F.5.2 Discussion of location for max dB/dt × B0 F.5.3 Rationale for test frequencies F.5.4 Rationale for scan duration |
| 155 | F.5.5 Rationale for test temperature F.6 Vibration measurement equipment consideration |
| 156 | Annex G (informative) Gradient vibration patent declaration form |
| 158 | Annex H (informative) Assessment of dielectric and thermal parameters H.1 Introduction H.1.1 General H.1.2 HPM Considerations H.1.3 LPM Considerations H.2 Dielectric parameters H.2.1 General |
| 159 | H.2.2 Method 1 H.2.3 Method 2 H.2.4 Method 3 |
| 160 | H.2.5 Good measurement practices to achieve precise dielectric measurements H.2.5.1 General H.2.5.2 Method 1 (open coaxial probe) H.2.5.3 Method 2 (slotted line) |
| 161 | H.2.5.4 Method 3 (static conductivity meter) H.3 Thermal parameters H.3.1 General considerations H.3.2 Methods H.3.2.1 Introduction |
| 162 | H.3.2.2 Method to determine heat capacity H.3.2.3 Method to determine thermal conductivity |
| 163 | Annex I (informative) RF exposure system validation method I.1 Objective I.2 Validation procedure |
| 164 | I.3 Standard test object definitions |
| 165 | I.4 Example SAIMD exposure simulation target values I.4.1 General |
| 167 | I.4.2 Example SAIMD-1 target values |
| 169 | I.4.3 Example SAIMD-2 target values |
| 171 | I.5 Test object measurement I.6 Compare simulation target values to measured results |
| 173 | Annex J (informative) MR scanner RF transmit coil |
| 175 | Annex K (informative) Current distribution on the AIMD as a function of the phase distribution of the incident field K.1 Background K.2 Phase gradients in lossy dielectrics |
| 176 | K.3 Transfer function to determine induced heating |
| 178 | Annex L (informative) Tissue simulating medium formulations L.1 Rationale L.2 HPM and LPM Recipes |
| 180 | L.3 Example preparation methods L.3.1 General L.3.2 LPM formulation L.3.3 PAA HPM formulation |
| 182 | Annex M (informative) Generation of incident fields M.1 General M.2 Background M.3 Uniform incident field distributions |
| 188 | M.4 Non-uniform incident field distributions |
| 196 | M.5 Pathway modifications |
| 197 | Annex N (informative) Dielectric and thermal tissue properties |
| 201 | Annex O (informative) Gradient field injected testing — AIMD electrode tissue impedance determination method O.1 Background O.2 Theory O.3 Test setup |
| 204 | O.4 Tissue interface network implementation |
| 206 | Annex P (informative) Estimation of conservative B1 and 10 g averaged E-field values for Tier 1 for RF-induced heating and RF malfunction P.1 Objective P.2 Methods |
| 212 | P.3 Results P.4 Scaling of results for Tier 1 of RF-induced malfunction |
| 214 | Annex Q (informative) AIMD configuration |
| 215 | Annex R (informative) Electrically excitable tissue stimulation, terms and definitions R.1 General R.2 Stimulation Assessment R.2.1 General |
| 216 | R.2.2 Charge duration curve comparison R.2.3 Strength duration curve comparison |
| 217 | Annex S (informative) Combined fields test S.1 Example of MR protocol implementation S.1.1 General |
| 218 | S.1.2 Neurological examinations examples |
| 219 | S.1.3 Thoracic examinations examples |
| 220 | S.1.4 Upper limbs examinations examples |
| 221 | S.1.5 Pelvic examinations examples S.1.6 Lower limb examination examples |
| 222 | S.2 Example of system test configuration |
| 224 | Annex T (informative) General methods for modelling dB/dt levels in MR gradient coils T.1 General T.2 Gradient design methods T.2.1 Method of designing single coil T.2.2 Method of designing different coil axes |
| 225 | T.2.3 Method of designing a set of three gradient axes |
| 226 | T.2.4 Methods of designing the family of 60-cm bore coil designs T.2.5 Methods of designing the family of 70-cm bore coil designs |
| 227 | T.3 Gradient field calculation methods T.3.1 General method for calculating magnetic fields within coils T.3.2 Region for general magnetic field calculations within coils |
| 228 | T.4 dB/dt calculation methods T.4.1 Derivation of dB/dt T.4.2 Specifics regarding generation of dB/dt table |
| 230 | Bibliography |
