3T 31P/1H calf muscle coil for 1H and 31P MRI/MRS integrated with NIRS data acquisition

Abstract Purpose Our aim was to design and build a 3T 31 P/ 1 H calf coil that is capable of providing both good 31 P and 1 H transmit and receive performance, as well as being capable of accommodating a near‐infrared spectroscopy (NIRS) device for simultaneous NIRS data and MRI/MRS acquisition. Method In this work, we propose a new 3T 31 P/ 1 H birdcage combination design consisting of two co‐centrically positioned birdcages on the same surface to maximize transmit efficiency and sensitivity for both nuclei. The 31 P birdcage is a high‐pass birdcage, whereas the 1 H birdcage is a low‐pass one to minimize coupling. The diameter of the 31 P/ 1 H birdcage combination was designed to be large enough to accommodate a NIRS device for simultaneous NIRS data and MRI/MRS acquisition. Results The one‐layer coil structure of the birdcage combination significantly streamlines the mechanical design and coil assembly process. Full‐wave simulation results show that the 31 P and 1 H are very well decoupled with each other, and the 1 H and 31 P SNR surpasses that of their standalone counterparts in the central area. Experiment results show that the inclusion of a NIRS device does not significantly affect the performance of the coil, thus enabling simultaneous NIRS and MRI readouts during exercise. Conclusion Our findings demonstrate the feasibility and effectiveness of this dual‐tuned coil design for combined NIRS and MRS measurements, offering potential benefits for studying metabolic and functional changes in the skeletal muscle in vivo.