1H-MRS of NAD+ and tryptophan in human brain at 3T in under 5 minutes using a spectrally-selective single-slice pulse sequence

Motivation: NAD+ and tryptophan are important in energy metabolism, DNA repair, mitochondrial function, and aging. Both have recently been observed in brain at 7T, but observation at 3T is more challenging and has not been shown previously. Goal(s): To detect NAD+ and tryptophan at 3T in brain in a clinically feasible scan time less than 5 minutes. Approach: A single slice spectroscopy sequence with spectrally selective excitation was developed and optimized, allowing high sensitivity acquisition. Results: The H2 (9.3 ppm) and H6 (9.1 ppm) peaks of NAD+ and the indole (10.1 ppm) peak of tryptophan are both unambiguously observed in four healthy subjects. Impact: The ability to identify NAD+ and tryptophan at 3T in less than 5 minutes has the potential to significantly enhance the adoption of this method as part of existing neuroimaging protocols.