Abstract
As a phosphorus-containing molecule, nicotinamide adenine dinucleotide is visible by phosphorus magnetic resonance spectroscopy ((31)P-MRS). However, the relatively low cellular levels of its oxidised (NAD(+)) and reduced (NADH) forms and a significant peak overlap hinder their evaluation in live tissues. This problem is critical when using (31)P-MR spectroscopic imaging, where signals are localised from limited tissue volumes. We have reported improvements in spectral resolution of (31)P-MRSI of human tissues in situ using a strict optimisation of the static magnetic field (B(0) shimming) and (1)H-irradiation during (31)P acquisition. Given this, we aimed to demonstrate if these improvements allowed us to measure the in vivo intracellular levels of NAD(+) and NADH at the relatively low magnetic field of 1.5 tesla (T). Our results show the feasibility of the in vivo determination of NAD(+) and NADH from relatively small volumes of human tissues studied at 1.5 T. These results are clinically relevant as the currently available systems for human use mainly operate at 1.5 or 3.0.