A Frequency Translation System for Multi-Channel, Multi-Nuclear MR Spectroscopy.

Objective: Most MRI scanners are equipped to receive signals from 1 H array coils but few support multi-channel reception for other nuclei. Using receive arrays can provide significant SNR benefits, usually exploited to enable accelerated imaging, but the extension of these arrays to non- 1 H nuclei has received less attention because of the relative lack of broadband array receivers. Non- 1 H nuclei often have low sensitivity and stand to benefit greatly from the increase in SNR that arrays can provide. This paper presents a cost-effective approach for adapting standard 1 H multi-channel array receivers for use with other nuclei - in this case, 13 C. Methods: A frequency translation system has been developed that uses active mixers residing at the magnet bore to convert the received signal from a non- 1 H array to the 1 H frequency for reception by the host system receiver. Results: This system has been demonstrated at 4.7T and 7T while preserving SNR and isolation. 1 H decoupling, particularly important for 13 C detection, can be straightforwardly accommodated. Conclusion: Frequency translation can convert 1 H-only multi-channel receivers for use with other nuclei while maintaining SNR and channel isolation while still enabling 1 H decoupling. Significance: This work allows existing multi-channel MRI receivers to be adapted to receive signals from nuclei other than 1 H, allowing for the use of receive arrays for in vivo multi-nuclear NMR.