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Accurate estimation of specific absorption rate (SAR) is essential for evaluating both hardware and implant safety, yet thermometry and simulation\u2010only approaches face limitations. In addition, these evaluations are typically performed within the MR scanner, where failures or excessive loading can damage the transmit chain and result in costly repairs and scanner downtime. To overcome these challenges, alternative experimental approaches that enable direct and controlled SAR validation outside the MR environment are needed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study demonstrates direct SAR validation of RF hardware and implants in a dedicated B0\u2010free RF safety laboratory. The work aims to establish direct SAR measurement as a practical and accurate alternative for quantitative safety verification while expanding the range of tools available for MR hardware evaluation beyond the constraints of the scanner environment.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Hardware assessments were conducted in the safety lab equipped with a 16\u2010channel broadband RF amplifier system (45\u2013450\u00a0MHz), a 100\u00a0dB shielded Faraday cage, automated 3D and 1D motion systems, and a high\u2010precision SAR probe. For coil validation, direct SAR mapping was performed on a custom\u2010built parallel transmit (pTx) coil and a commercial single\u2010channel RF coil at 447 and 297\u00a0MHz, respectively, and results were compared with electromagnetic simulations. Transfer function (TF) validation for a directional DBS electrode at 128\u00a0MHz was performed in a rectangular electric\u2010field generator, whose field distribution was first validated using the SAR probe. The same probe was then used to compare measured SAR with TF\u2010based SAR predictions, providing a direct quantitative validation of the TF method.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Measured SAR distributions showed strong quantitative agreement with simulations across all experiments. For the 8\u2010channel pTx head coil at 447\u00a0MHz, the normalized root\u2010mean\u2010square error (NRMSE) across four excitation patterns was below 13%. For the commercial single\u2010channel head coil at 297\u00a0MHz, plane\u2010wise comparisons across axial, coronal, and sagittal slices yielded an average NRMSE value of 7.18%, demonstrating spatial consistency between measured and simulated fields. The electric\u2010field generator used for DBS transfer function (TF) validation exhibited 3.68% NRMSE relative to simulation, confirming accurate field reproduction. SAR measurements using the same probe further showed close agreement with TF\u2010based SAR predictions across all seven lead trajectories, confirming both the accuracy and broadband applicability of the direct SAR method.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Direct SAR measurement provides a reliable and quantitative approach for validating RF coil and implant safety, matching the accuracy of conventional scanner\u2010based thermometry and simulation methods. Conducting these measurements in a B0\u2010free RF safety laboratory further simplifies and accelerates the process by eliminating magnetic field constraints and the waiting periods required for the setup to return to thermal equilibrium in thermometric techniques. This configuration provides an efficient and controlled platform for systematic SAR validation across a wide range of MR frequencies.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70636","type":"journal-article","created":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T05:29:22Z","timestamp":1787117362000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["SAR validation of RF coils and implants in a B0\u2010free RF safety laboratory"],"prefix":"10.1002","volume":"53","author":[{"given":"Nur Izzati Huda","family":"Zulkarnain","sequence":"first","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mazin M.","family":"Mustafa","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alireza","family":"Sadeghi\u2010Tarakameh","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mert","family":"Ates","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeromy","family":"Thotland","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steve","family":"Jungst","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arcan","family":"Erturk","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lance","family":"DelaBarre","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matt","family":"Waks","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Russell L.","family":"Lagore","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kamil","family":"Ugurbil","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gregory J.","family":"Metzger","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gregor","family":"Adriany","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yigitcan","family":"Eryaman","sequence":"additional","affiliation":[{"name":"Center for Magnetic Resonance Research University of Minnesota  Minneapolis Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,8,18]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.26564"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.22632"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.28131"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.28093"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41592\u2010024\u201002472\u20107"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.30476"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.30315"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10334\u2010023\u201001085\u2010z"},{"key":"e_1_2_8_10_1","unstructured":"Strongest MRI scanner in the world will be built in the Netherlands. 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