The specific absorption rate (SAR) estimates the amount of power absorbed by the tissue and is determined by the electrical conductivity and the E-field. Conductivity can be estimated using Electric Properties Tomography (EPT) but only the E-field component associated with B + 1 can be deduced from B 1mapping. Herein, a correction factor was calculated to compensate for the differences between the actual SAR and the one obtained with B + 1 . Numerical simulations were performed for 27 head models at 128 MHz. Ground-truth local-SAR and 10g-SAR (SAR GT ) were computed using the exact electrical conductivity and the E-field. Estimated local-SAR and 10g-SAR (SAR EST ) were computed using the electrical conductivity obtained with a convectionreaction EPT and the E-field obtained from B + 1 . Correction factors (CFs) were estimated for gray matter, white matter, and cerebrospinal fluid (CSF). A comparison was performed for different levels of signal-to-noise ratios (SNR). Local-SAR/10g-SAR CF was 3.08 ± 0/06 / 2.11 ± 0.04 for gray matter, 1.79 ± 0/05 / 2.06 ± 0.04 for white matter, and 2.59 ± 0/05 / 1.95 ± 0.03 for CSF. SAR EST without CF were underestimated (ratio across [∞ -25] SNRs: 0.52 ± 0.02 for local-SAR; 0.55 ± 0.01 for 10g-SAR). After correction, SAR EST was equivalent to SAR GT (ratio across [∞ -25] SNRs: 0.97 ± 0.02 for local-SAR; 1.06 ± 0.01 for 10g-SAR). SAR maps based on B + 1 can be corrected with a correction factor to compensate for potential differences between the actual SAR and the SAR calculated with the E-field derived from B + 1 .

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