Radio Frequency Coil for Dual-Nuclei MR Muscle Energetics Investigation Based on Two Capacitively Coupled Periodic Wire Arrays

In this letter, we describe a dedicated radio frequency (RF) coil for magnetic resonance imaging and spectroscopy at 4.7 T optimized for investigation of muscle energetics in a human forearm. The coil operating at the Larmor frequencies of protons $^1$H (200.1 MHz) and phosphorous $^{31}$P (81 MHz) is based on two cylindrical periodic structures made of thin metal wires with tips interconnected through structural capacities of printed overlapping patches and sliding electric contacts. By independently exciting two orthogonal eigenmodes of the structure, the coil can be tuned and matched at both frequencies without lumped capacitors and cover the target region of interest for the forearm flexor muscles.