Whole brain 31 P MRSI at 7T with a dual-tuned receive array

The design and performance of a novel head coil setup for ${}^{31}$ P spectroscopy at ultra-high field strengths (7T) is presented. The described system supports measurements at both the ${}^1$ H and ${}^{31}$ P resonance frequencies.

The novel coil consists of 2, actively detunable, coaxial birdcage coils to give homogeneous transmit, combined with a double resonant 30 channel receive array. This allows for anatomical imaging combined with ${}^{31}$ P acquisitions over the whole head, without changing coils or disturbing the subject. A phosphate buffer phantom and 3 healthy volunteers were scanned with a pulse acquire CSI sequence using both the novel array coil and a conventional transceiver birdcage. Four different methods of combining the array channels were compared at 3 different levels of SNR.

The novel coil setup delivers significantly increased ${}^{31}$ P SNR in the peripheral regions of the brain, reaching up to factor 8, while maintaining comparable performance relative to the birdcage in the center.

The new system offers the potential to acquire whole brain ${}^{31}$ P MRSI with superior signal relative to the standard options.