First In Vivo ²³ Na Human Imaging at 10.5 T Using a Combined Sodium‐Proton Transceiver Body Array

Purpose To demonstrate the first in vivo human 23 Na MRI at 10.5 T using a novel dual‐tuned transceiver body array and to evaluate a self‐gating approach for respiratory motion compensation, focusing on renal imaging. Methods A custom‐built eight‐channel 23 Na‐loop 1 H‐dipole transceiver array was designed, constructed, and characterized. Safe operation was ensured through comparison of electromagnetic simulations against B 1 + and SAR phantom measurements. A programmable motion phantom mimicked respiratory motion to assess self‐gating for both the 23 Na and 1 H acquisitions. Finally, in vivo human abdominal 23 Na and 1 H data were acquired in three healthy volunteers under free breathing, applying the self‐gating approach. Results The array's electromagnetic model showed good agreement with experimental data, with B 1 + NRMSE values of 0.16 for 23 Na, 0.32 for 1 H, and SAR NRMSE values of 0.35 for 23 Na and 0.22 for 1 H. Total power limits of 125 and 42 W were implemented for 23 Na and 1 H, respectively. The motion phantom study confirmed that both 23 Na and 1 H self‐gating signals accurately tracked the programmed ground truth motion (correlation coefficients: 0.979 for 23 Na, 0.995 for 1 H). Motion binning significantly improved image sharpness as quantitatively evaluated in the phantom. In vivo, self‐gating robustly captured respiratory motion and effectively enabled motion compensation, as shown in binned images with enhanced anatomical detail. Conclusions We successfully performed the first in vivo human 23 Na MRI at 10.5 T. The developed dual‐tuned array and validated self‐gating technique enable 10.5 T imaging in humans, paving the way for quantitative studies of sodium homeostasis and advancing diagnostic capabilities.