Detection of cerebral NAD+ in humans at 7T.

PURPOSE: To develop 1 H-based MR detection of nicotinamide adenine dinucleotide (NAD+ ) in the human brain at 7T and validate the 1 H results with NAD+ detection based on 31 P-MRS.
METHODS: 1 H-MR detection of NAD+ was achieved with a one-dimensional double-spin-echo method on a slice parallel to the surface coil transceiver. Perturbation of the water resonance was avoided through the use of frequency-selective excitation. 31 P-MR detection of NAD+ was performed with an unlocalized pulse-acquire sequence.
RESULTS: Both 1 H- and 31 P-MRS allowed the detection of NAD+ signals on every subject in 16 min. Spectral fitting provided an NAD+ concentration of 107 ± 28 μM for 1 H-MRS and 367 ± 78 μM and 312 ± 65 μM for 31 P-MRS when uridine diphosphate glucose (UDPG) was excluded and included, respectively, as an overlapping signal.
CONCLUSIONS: NAD+ detection by 1 H-MRS is a simple method that comes at the price of reduced NMR visibility. NAD+ detection by 31 P-MRS has near-complete NMR visibility, but it is complicated by spectral overlap with NADH and UDPG. Overall, the 1 H- and 31 P-MR methods both provide exciting opportunities to study NAD+ metabolism on human brain in vivo.