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

Abstract

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 MRS pulse sequence for the in vivo, localized H MRS detection of NAD from the human brain. 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. Spectra acquired from a voxel placed in subjects' occipital lobe consisted of downfield peaks from the H , H , and H 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). We demonstrated the feasibility and robustness of a newly developed H 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.