Advancements in Multinuclear Multichannel NMR and MRI

The introduction of receive arrays revolutionized ^1H MRI and in vivo NMR by increasing SNR and enabling accelerated imaging. All MRI scanners manufactured today are equipped to receive signals from ^1H array coils, but few support multi-channel reception for other nuclei. The extension of receive arrays to non^1H nuclei has proven difficult because of the lack of broadband array receivers. These nuclei often have low sensitivity and stand to benefit greatly from the increase in SNR arrays provide. This dissertation presents a variety of technologies that have been developed to enable the development and use of X-nuclear and multi-nuclear arrays. Frequency conversion receiver front-ends provide a straightforward and cost-effective approach for adapting standard ^1H multi-channel array receivers for use with other nuclei. Two generations of frequency translation receiver front-ends have been developed that use active mixers to convert the received signal from a non^1H array to the ^1H frequency for reception by the host system receiver. This first-generation system has been demonstrated on 4.7T and 7T systems without any decrease in SNR as compared to the stock systems, and has been shown to be capable of accommodating ^1H decoupling. The second-generation receiver was developed to add the capability to simultaneously convert signals received from multiple nuclei as well as to streamline the setup and use of the translation system. Frequency translation has been shown to be able to convert ^1H-only multi-channel receivers for use with other nuclei with minimal degradation of SNR. In addition, a standalone broadband system capable of simultaneous multi-nuclear imaging and spectroscopy at 1T and 4.7T has been developed. This system can either operate completely independently or interface with existing systems. The broadband system has been demonstrated with simultaneous imaging and spectroscopy of three nuclei. This work allows existing multi-channel MRI receivers to be adapted to receive signals from nuclei other than hydrogen, allowing for the use of receive arrays for in vivo multi-nuclear NMR