{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,12]],"date-time":"2026-07-12T05:07:32Z","timestamp":1783832852450,"version":"3.55.0"},"reference-count":43,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T00:00:00Z","timestamp":1781136000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T00:00:00Z","timestamp":1781136000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Magnetic Resonance Imaging"],"published-print":{"date-parts":[[2026,8]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:label\/>\n                    <jats:p>The B1+rms metric, requested by Active Implantable Medical Device (AIMD) manufacturers, characterizes MR equipment radiofrequency (RF) electromagnetic field outputs. Specific Absorption Rate (SAR) is the physiologically appropriate power deposition metric for patient heating considerations, but B1+rms is better suited for implant purposes because it more directly assesses AIMD\/RF exposure interactions in conductive implants. The formal SAR definitions only specify limits, not how to compute SAR, thus each MR equipment make, model and software version may compute SAR differently via proprietary algorithms. Since a wide range of SAR occurs for a given B1+ exposure condition, SAR estimates are larger than the actual exposure. Consequently, the SAR safety margin size that fulfills limit requirements is unknown to AIMD manufacturers and MR equipment users. By design, the B1+rms metric has no limit or safety margin, but is precisely defined to enable transparency to all B1+rms users. Because B1+rms enables a more precise assessment of AIMD\/RF exposure interactions, more RF performance becomes available for MR Conditional AIMD purposes. The AIMD manufacturer is responsible to assess all relevant uncertainties, set appropriate safety margins, and provide device\u2010specific limits. These tasks are simplified with B1+rms. Additionally, since MR image quality requires control of B1+ outputs, the clinical workflow of AIMD scanning can be improved with B1+rms labelling whereas the SAR variability between patients undergoing the same B1+ exposure may require unique sequence adjustments to comply with MR Conditional SAR constraints, impacting image quality. However, confusion remains regarding B1+rms computation, application, and why it is an independently sufficient and superior metric for MR Conditional labeling purposes. This review compares the SAR and B1+rms metrics, their suitability for AIMD labeling, describes how AIMD manufacturers use B1+rms, and clarifies various B1+rms concerns. Reasons why B1+rms is a superior RF measure for MR Conditional labeling purposes are identified.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Evidence Level<\/jats:title>\n                    <jats:p>5.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Technical Efficacy<\/jats:title>\n                    <jats:p>Stage 1.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/jmri.70371","type":"journal-article","created":{"date-parts":[[2026,6,12]],"date-time":"2026-06-12T06:00:11Z","timestamp":1781244011000},"page":"333-345","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["<scp>B1+rms<\/scp>\n                    for Implants: A Review of Intended Use"],"prefix":"10.1002","volume":"64","author":[{"given":"Michael","family":"Steckner","sequence":"first","affiliation":[{"name":"MKS Consulting  Beachwood Ohio USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-4182-968X","authenticated-orcid":false,"given":"Louai","family":"Al\u2010Dayeh","sequence":"additional","affiliation":[{"name":"Boston Scientific Neuromodulation  Valencia California USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,6,11]]},"reference":[{"key":"e_1_2_8_2_1","unstructured":"\u201cIEC 60601\u20132\u201033 Medical Electrical Equipment\u2014Part 2\u201333: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d1995 Edition 1."},{"key":"e_1_2_8_3_1","unstructured":"\u201cIEC 60601\u20132\u201033 Medical Electrical Equipment\u2014Part 2\u201333: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d2002 Edition 2."},{"key":"e_1_2_8_4_1","unstructured":"\u201cIEC 60601\u20102\u201033 Medical Electrical Equipment\u2014Part 2\u201033: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d2006 Edition 2.1."},{"key":"e_1_2_8_5_1","unstructured":"\u201cIEC 60601\u20102\u201033 Medical Electrical Equipment\u2014Part 2\u201033: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d2022 Edition 4.0."},{"key":"e_1_2_8_6_1","unstructured":"ISO 14971 \u201cMedical Devices\u2014Application of Risk Management to Medical Devices \u201d2019 Geneva Switzerland."},{"key":"e_1_2_8_7_1","unstructured":"https:\/\/www.ismrm.org\/workshops\/Safety17\/program.htm."},{"key":"e_1_2_8_8_1","unstructured":"\u201cIEC 60601\u20102\u201033 Medical Electrical Equipment\u2014Part 2\u201033: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d2010 Edition 3."},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.rli.0000185898.59140.91"},{"key":"e_1_2_8_10_1","unstructured":"ISO TS 10974 \u201cAssessment of the Safety of Magnetic Resonance Imaging for Patients With an Active Implantable Medical Device \u201d2012 Edition 1."},{"key":"e_1_2_8_11_1","unstructured":"ISO IS 10974 \u201cAssessment of the Safety of Magnetic Resonance Imaging for Patients With an Active Implantable Medical Device \u201d2025 Committee Draft 62B\/1401\/CDV."},{"key":"e_1_2_8_12_1","first-page":"66","article-title":"The Impact of Body Composition on Energy Expenditure During Walking and Running in Young Adults. HNES Educator Scholarship","volume":"19","author":"Pauley A.","year":"2016","journal-title":"Journal of Exercise Physiology"},{"key":"e_1_2_8_13_1","unstructured":"X.Chen Y.Hamamura andM.Steckner \u201cNumerical Simulation of SAR for 3T Whole Body Coil: Effect of Patient Loading Positions on Local SAR Hotspot ISMRM \u201d2010."},{"key":"e_1_2_8_14_1","unstructured":"https:\/\/itis.swiss\/virtual\u2010population\/tissue\u2010properties\/database\/."},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.pbiomolbio.2011.09.017"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.29894"},{"key":"e_1_2_8_17_1","unstructured":"K. R.Foster \u201cThermal Considerations for Design of RF Exposure Guidelines ICNIRP Meeting \u201d2015 Istanbul Turkey."},{"key":"e_1_2_8_18_1","unstructured":"https:\/\/www.fda.gov\/medical\u2010devices\/industry\u2010medical\u2010devices\/letters\u2010industry."},{"key":"e_1_2_8_19_1","unstructured":"\u201cIEC 60601\u20102\u201033 Medical Electrical Equipment\u2014Part 2\u201033: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d2015 Edition 3.2."},{"key":"e_1_2_8_20_1","unstructured":"\u201cIEC 60601\u20102\u201033 Medical Electrical Equipment\u2014Part 2\u201033: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis \u201d2013 Edition 3.1."},{"key":"e_1_2_8_21_1","doi-asserted-by":"publisher","DOI":"10.1002\/nbm.4440"},{"key":"e_1_2_8_22_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.mri.2018.03.008"},{"key":"e_1_2_8_23_1","unstructured":"M.Zaitsev \u201cPersonal Communication.\u201d"},{"key":"e_1_2_8_24_1","unstructured":"ISO TS 10974 \u201cAssessment of the Safety of Magnetic Resonance Imaging for Patients With an Active Implantable Medical Device \u201d2018 Edition 2."},{"key":"e_1_2_8_25_1","doi-asserted-by":"publisher","DOI":"10.1016\/0022\u20102364(85)90349\u2010X"},{"key":"e_1_2_8_26_1","first-page":"162","volume-title":"Adaptive Coil Control: SNR Optimization of a TR Volume Coil for Single Voxel MRS at 3T","author":"Seifert F.","year":"2002"},{"key":"e_1_2_8_27_1","first-page":"425","volume-title":"The Technology and Techniques of 4T Body Imaging","author":"Vaughan T.","year":"2003"},{"key":"e_1_2_8_28_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4903894"},{"key":"e_1_2_8_29_1","doi-asserted-by":"publisher","DOI":"10.1109\/TEMC.2018.2877526"},{"key":"e_1_2_8_30_1","unstructured":"P.LerouxandA.Marilier \u201cMethod for Calibrating the Amplitude of Radiofrequency Excitation of a Nuclear Magnetic Resonance Imaging Apparatus \u201d1988 USA patent #4 739 267."},{"key":"e_1_2_8_31_1","first-page":"372","volume-title":"Electronic Method for Eliminating Prescan RF Transmitter Amplitude Adjustment","author":"Edelstein W. A.","year":"1987"},{"key":"e_1_2_8_32_1","first-page":"1129","volume-title":"A Novel Method for Rapid Pulse Angle Optimization","author":"Meulen P.","year":"1986"},{"key":"e_1_2_8_33_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.22902"},{"key":"e_1_2_8_34_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.24158"},{"key":"e_1_2_8_35_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.29151"},{"key":"e_1_2_8_36_1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1522-2594(199903)41:3<474::AID-MRM8>3.0.CO;2-K"},{"key":"e_1_2_8_37_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910350215"},{"key":"e_1_2_8_38_1","unstructured":"M. K.Akter \u201cComprehensive MRI Safety Assessment: Impact of Strain\u2010Relief Loop Position Lateral Movement and Varying Field Strengths on RF\u2010Induced Heating of Medical Implants \u201d2025 https:\/\/uh\u2010ir.tdl.org\/items\/0a1bf693\u2010ca9f\u201048d7\u2010a999\u201043620f2f3e24."},{"key":"e_1_2_8_39_1","unstructured":"ISO TR 21900 \u201cGuidance for Uncertainty Analysis Regarding the Application of ISO TS 10974 \u201d2018 https:\/\/www.iso.org\/standard\/72119.html."},{"key":"e_1_2_8_40_1","doi-asserted-by":"publisher","DOI":"10.1039\/c2ay90034c"},{"key":"e_1_2_8_41_1","first-page":"3105","volume-title":"Changes in RF Transmit Gain Before and After DBS Lead Placement in 36 Consecutive Patients","author":"Bernstein M. A.","year":"2009"},{"key":"e_1_2_8_42_1","doi-asserted-by":"publisher","DOI":"10.1002\/jmri.21159"},{"key":"e_1_2_8_43_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.hrthm.2013.10.009"},{"key":"e_1_2_8_44_1","unstructured":"IEC60601\u20102\u201033 \u201cMedical Electrical Equipment\u2014Part 2\u201033: Particular Requirements for the Basic Safety and Essential Performance of Magnetic Resonance Equipment for Medical Diagnosis CORRIGENDUM 1 \u201d2012 https:\/\/webstore.iec.ch\/en\/publication\/2648."}],"container-title":["Journal of Magnetic Resonance Imaging"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/jmri.70371","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/jmri.70371","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/jmri.70371","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,12]],"date-time":"2026-07-12T04:49:06Z","timestamp":1783831746000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/jmri.70371"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,11]]},"references-count":43,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2026,8]]}},"alternative-id":["10.1002\/jmri.70371"],"URL":"https:\/\/doi.org\/10.1002\/jmri.70371","archive":["Portico"],"relation":{},"ISSN":["1053-1807","1522-2586"],"issn-type":[{"value":"1053-1807","type":"print"},{"value":"1522-2586","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,11]]},"assertion":[{"value":"2026-02-16","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-05-04","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-06-11","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}