A Numerical Alternative to MR Thermometry for Safety Validation of Multi-Channel RF Transmit Coils.

purposeThis study proposes a numerical technique to estimate peak local specific absorption rate (SAR) uncertainty of multi-channel RF coils during the process of safety validation as an alternative to experimental temperature and electric-field measurements, and demonstrates its use to enable human studies at 10.5 T.

methodsTo ensure patient safety, SAR limits established under international guidelines must not be exceeded. Predicting SAR on state-of-the-art parallel transmit systems relies on electromagnetic simulations, which require extensive experimental validation. Despite a well-established validation workflow, SAR prediction errors are unavoidable and must be quantified as a safety margin. While MRT tests are commonly used for this purpose, their technical challenges necessitate an alternative. The proposed technique propagates the error between experimentally and numerically acquired

resultsThe proposed numerical technique proved more conservative than existing MRT-based SAR error quantification methods across all tested scenarios. Its application to validate three state-of-the-art head coils (16Tx/32Rx, 16Tx/80Rx, and 16Tx/128Rx) led to regulatory approval for human head imaging and high-quality diffusion and functional MRI results at 10.5 T.

conclusionThe proposed technique requires only the experimental acquisition of