Evaluation of Human Brain Metabolism using Five-Dimensional Echo Planar J-resolved Spectroscopic Imaging and Covariance J-resolved Spectroscopy

Magnetic resonance spectroscopy (MRS) is a non-invasive tool capable of assessing metabolic changes in vivo. Point-resolved spectroscopy (PRESS) is a single-voxel based method which yields a one dimensional (1D) spectrum from a volume of interest, and is typically used to monitor metabolites in the brain. Several improvements have been added to this technique to enhance metabolite detection, one of which includes the addition of a second spectral dimension capable of encoding the J values of metabolites, known as J-resolved spectroscopy (JPRESS). Utilizing non-uniform sampling and compressed sensing methods, it is even possible to obtain these two dimensional (2D) spectra from multiple spatial dimensions, giving rise to accelerated J-resolved spectroscopic imaging (JRESI) techniques. This work presents novel processing and quantitation techniques capable of further enhancing the applications of both the JPRESS and JRESI methods. For JPRESS, a technique incorporating the covariance transformation is used to greatly improve spectral resolution in the indirect dimension. For JRESI, novel processing methods are used to quantify Glutamate, a prominent neurotransmitter in the brain, and other neuro-metabolites