Single‐Voxel 1H MR spectroscopy of cerebral nicotinamide adenine dinucleotide (NAD+) in humans at 7T using a 32‐channel volume coil

Purpose Reliable monitoring of tissue nicotinamide adenine dinucleotide (NAD+) concentration may provide insights on its roles in normal and pathological aging. In the present study, we report a 1H MRS pulse sequence for the in vivo, localized 1H MRS detection of NAD+ from the human brain. Methods Studies were carried out on a 7T Siemens MRI scanner using a 32‐channel product volume coil. The pulse sequence consisted of a spectrally selective low bandwidth E‐BURP‐1 90° pulse. PRESS localization was achieved using optimized Shinnar‐Le Roux 180° pulses and overlapping gradients were used to minimize the TE. The reproducibility of NAD+ quantification was measured in 11 healthy volunteers. The association of cerebral NAD+ with age was assessed in 16 healthy subjects 26–78 years old. Results Spectra acquired from a voxel placed in subjects' occipital lobe consisted of downfield peaks from the H2, H4, and H6 protons of the nicotinamide moiety of NAD+ between 8.9–9.35 ppm. The mean ± SD within‐session and between‐session coefficients of variation were found to be 6.14 ± 2.03% and 6.09 ± 3.20%, respectively. In healthy volunteers, an age‐dependent decline of the NAD+ levels in the brain was also observed (β = −1.24 μM/y, SE = 0.21, P < 0.001). Conclusion We demonstrated the feasibility and robustness of a newly developed 1H MRS technique to measure localized cerebral NAD+ at 7T MRI using a commercially available RF head coil. This technique may be further applied to detect and quantify NAD+ from different regions of the brain as well as from other tissues.