Low‐γ X‐nuclear MRS and imaging have played a key role in studying metabolism and physiopathology, especially at ultrahigh fields. We design and demonstrate a novel and simple dual‐frequency RF resonant coil that can operate at both low‐γ X‐nuclear and proton frequencies. The dual‐frequency resonant coil comprises an LC coil loop and a tuning‐matching circuit bridged by two short wires of the desired length to generate two resonant modes: one for proton MRI and the other for low‐γ X‐nuclear MRS imaging with a large difference in their Larmor frequencies at ultrahigh fields. The coil parameters for the desired coil size and resonant frequencies can be determined via numerical simulations based on LC circuit theory. We designed, constructed, and evaluated several prototype surface coils and quadrature array coils for 1H and 2H or 17O imaging, with small‐sized (diameter ≤ 5 cm) coils evaluated using a 16.4 T animal scanner, and a large‐sized (15 cm diameter) coil on a 7 T human scanner. All coils could be tuned/matched and driven in the single coil or array coil mode to the resonant frequencies of 1H (698 and 298 MHz), 2H (107 and 45.8 MHz), or 17O (94.7 and 40.4 MHz) for imaging measurements and evaluation at 16.4 and 7 T, respectively. The dual‐frequency resonant coil or array provides adequate detection sensitivity for 1H MRI and excellent performance for low‐γ X‐nuclear MRS imaging applications, and excellent coil decoupling efficiency between the array coils at both resonant frequencies with an optimal geometric overlap. It provides a simple, cost‐effective dual‐frequency RF coil solution to perform low‐γ X‐nuclear MRS imaging for preclinical and human applications, especially at ultrahigh fields.

We compared the B1 efficiency of a newly developed dual-frequency surface coil operating at proton and low-g X-nuclei frequencies at 16.4T with that of traditional proton coil and X-nuclei coil, respectively. Both simulation and experimental results revealed that the B1 field strength of the new coil was similar to that of traditional coil at deuterium or oxygen-17 frequency though was significantly reduced at proton frequency, while their B1 distributions were identical for both proton and deuterium/oxygen-17 frequencies. The efficacy of the new coil for in-vivo deuterium metabolic imaging applications was demonstrated in normal and tumor rat brains.