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 H-1 MRS pulse sequence for the in vivo, localized H-1 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 degrees pulse. PRESS localization was achieved using optimized Shinnar-Le Roux 180 degrees 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 H-2, H-4, and H-6 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 (beta = -1.24 mu M/y, SE = 0.21, P < 0.001). Conclusion We demonstrated the feasibility and robustness of a newly developed H-1 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.