A Custom-Built, Cost-Efficient Lithium-7 Tx/Rx Coil for In Vivo 7Li Magnetic Resonance Imaging and Spectroscopy.

Abstract

X-nuclei magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are powerful tools for the in vivo investigation of metabolism. Most nuclei require a dedicated radio frequency (RF) coil for signal detection; however, RF coils are often expensive. Coupled with the need for experts to create RF coils, X-nuclei MR measurements are often inaccessible to the general user. In this paper, we present cost-efficient and easy to assemble ⁷Li RF coils that achieved comparable signal-to-noise ratios (SNRs) to their commercial counterpart. Our ⁷Li RF coils were built as single resonance, transmit-receive (Tx/Rx) coils with sufficient design flexibility to allow for future implementations for other nuclei. We found that for a mouse surface coil the optimal number of segmentation capacitors was two. In vitro ⁷Li MRS yielded a 75% SNR increase and in vivo ⁷Li MRS yielded a 42% SNR increase compared with a commercial dual-tuned surface coil. Finally, we demonstrated that in vivo ⁷Li MRI of lithium-fed mice is possible with a custom-built, 2-segment surface coil.