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

## TL;DR

This study demonstrates the first in vivo human sodium MRI at 10.5 T using a new dual-tuned array and a self-gating technique to reduce motion artifacts, particularly in the kidneys.

## Contribution

The first in vivo human 23Na MRI at 10.5 T using a dual-tuned transceiver array and validated self-gating for motion compensation.

## Key findings

- The dual-tuned array showed good agreement between simulations and measurements, with low B1+ and SAR NRMSE values.
- Self-gating signals accurately tracked respiratory motion in both phantom and in vivo experiments.
- Motion binning improved image sharpness and anatomical detail in in vivo sodium imaging.

## Abstract

To demonstrate the first in vivo human 23Na 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.

A custom‐built eight‐channel 23Na‐loop 1H‐dipole transceiver array was designed, constructed, and characterized. Safe operation was ensured through comparison of electromagnetic simulations against B1
+ and SAR phantom measurements. A programmable motion phantom mimicked respiratory motion to assess self‐gating for both the 23Na and 1H acquisitions. Finally, in vivo human abdominal 23Na and 1H data were acquired in three healthy volunteers under free breathing, applying the self‐gating approach.

The array's electromagnetic model showed good agreement with experimental data, with B1
+ NRMSE values of 0.16 for 23Na, 0.32 for 1H, and SAR NRMSE values of 0.35 for 23Na and 0.22 for 1H. Total power limits of 125 and 42 W were implemented for 23Na and 1H, respectively. The motion phantom study confirmed that both 23Na and 1H self‐gating signals accurately tracked the programmed ground truth motion (correlation coefficients: 0.979 for 23Na, 0.995 for 1H). 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.

We successfully performed the first in vivo human 23Na 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.