Non-Invasive Super-Resolution Mapping of Regional Neurochemical Profiles of Zebrafish Brain Using Localized Magnetic Resonance Spectroscopy at 28.2 T

Localized 1H magnetic resonance spectroscopy (MRS) is a powerful tool in pre-clinical and clinical neurological research, offering non-invasive insight into neurochemical composition in localized brain regions. Zebrafish (Danio rerio) have emerged as an in-creasingly utilized models in neurological disorder research, providing valuable insights into disease mechanisms. However, small size of the zebrafish brain and limited MRS sensitivity at low magnetic fields hinder comprehensive neurochemical analysis of local-ized brain regions. Here, we investigate the potential of ultra-high field (UHF) MR sys-tems, particularly 28.2 T, for this purpose. This work pioneers application of localized 1H spectroscopy in zebrafish brain at 28.2 T. Point resolved spectroscopy (PRESS) sequence parameters were optimized to reduce the impact of chemical shift displacement error and to enable molecular level information from distinct brain regions. Optimized parameters included gradient strength, excitation frequency, echo time and voxel volume specifically targeting the 0 – 4.5 ppm chemical shift regions. Exceptionally high-resolution cerebral metabolite spectra were successfully acquired from localized regions of the zebrafish brain in voxels as small as 125 nL, allowing for the identification and quantification of major brain metabolites with remarkable spectral clarity, including lactate, myo-inositol, crea-tine, alanine, glutamate, glutamine, phosphocholine, choline, taurine, aspartate, N-acetylaspartyl-glutamate (NAAG), N-acetylaspartate (NAA), and γ-aminobutyric acid (GABA). The unprecedented spatial resolution achieved in a small model organism ena-bled detailed comparisons of the neurochemical composition across distinct zebrafish brain regions, including the forebrain, midbrain, and hindbrain. This level of precision opens exciting new opportunities to investigate how specific diseases in zebrafish models influence the neurochemical composition of specific brain areas.