Evaluation of a new ¹H/³¹P dual‐tuned birdcage coil for ³¹P spectroscopy

Abstract

We introduce a new dual-tuned Hydrogen/Phosphorus (1H/31P) birdcage coil, referred to as split birdcage coil, and evaluate its performance using both simulations and magnetic resonance (MR) experiments on a 3 T MR scanner. The proposed coil simplifies the practical matters of tuning and matching, which makes the coil easily reproducible. Simulations were run with the Finite Difference in Time Domain (FDTD) method to evaluate the sensitivity and homogeneity of the magnetic field generated by the proposed 1H coils. Following simulations, MR experiments were conducted using both a phantom and human thigh to compare the proposed design with a currently available commercial dual-tuned flexible surface coil, referred to as flex surface coil, for signal to noise ratio (SNR) as well as homogeneity for the 31P coil. At regions deep within the human thigh, the split birdcage coil was able to acquire spectroscopic signal with a higher average SNR than the flex surface coil. For all regions except those close to the flex surface coil, the split birdcage coil matched or exceeded the performance of the flex surface coil.

Feasibility and repeatability of localized 31P‐MRS four‐angle saturation transfer (FAST) of the human gastrocnemius muscle using a surface coil at 7 T

“…Therefore, we used an oblique slab position trying to stay parallel to the coil as much as possible, but still in the gastrocnemius muscle. A more homogeneous B 1 + coverage could be achieved using a volume coil , an array of RF coils or simply a larger surface coil . This would be especially beneficial for human subjects with large layers of subcutaneous fat, which acts as a pad or cushion between the muscle and the coil .…”

“…A more homogeneous B 1 + coverage could be achieved using a volume coil , an array of RF coils or simply a larger surface coil . This would be especially beneficial for human subjects with large layers of subcutaneous fat, which acts as a pad or cushion between the muscle and the coil . Similarly, a shifted coil position, more parallel to the localization slab, could be used to improve the B 1 + the homogeneity in the slab.…”

Design and Development of a General‐Purpose Transmit/Receive (T/R) Switch for 3T MRI, Compatible for a Linear, Quadrature and Double‐Tuned RF Coil

“…For non-proton MRI/S, 1 H MRI is essential for localization and shimming the region of interest (7)(8)(9), which cannot be done using the non-proton nuclei due to its low signal-to-noise ratio (SNR). The low SNR in non-proton MRI/S is mainly caused by the low concentration and gyromagnetic ratio of the non-proton nuclei in the human body (5,9,10).…”

“…Magnetic resonance imaging/spectroscopy (MRI/S) of nuclei other than hydrogen is used to obtain information about metabolic processes in humans and animals (1)(2)(3)(4)(5)(6). For non-proton MRI/S, 1 H MRI is essential for localization and shimming the region of interest (7)(8)(9), which cannot be done using the non-proton nuclei due to its low signal-to-noise ratio (SNR). The low SNR in non-proton MRI/S is mainly caused by the low concentration and gyromagnetic ratio of the non-proton nuclei in the human body (5,9,10).…”

“…For non-proton MRI/S, 1 H MRI is essential for localization and shimming the region of interest (7)(8)(9), which cannot be done using the non-proton nuclei due to its low signal-to-noise ratio (SNR). The low SNR in non-proton MRI/S is mainly caused by the low concentration and gyromagnetic ratio of the non-proton nuclei in the human body (5,9,10). Therefore, a double-tuned radio frequency (RF) coil, which requires appropriate transmit/receive (T/R) switching hardware, is generally desired for MRI/S of a nucleus other than 1 H. Double-tuned RF coils, which require appropriate hardware, reduce image registration problems and the inconvenience of physically replacing the RF coils and T/R switches for different nuclear experiments (11).…”