With respect to quantification of metabolites in the brain, conventional methods of magnetic resonance spectroscopy (MRS) yield results that are highly variable and highly dependent on the sequence type being applied. This invention describes a novel MRS technique that involves preparing longitudinal steady states at different flip angles using trains of RF pulses interspersed with field gradients to quantify metabolites. The method allows quantification of metabolites and their relaxation rates under specified parameters, which may create new ways of analyzing and interpreting tissue properties or identifying and characterizing diseases of the human brain, including epilepsy, multiple sclerosis, stroke, cancer, and psychiatric diseases. In addition, due to the linear feature (equation), the quantification of metabolites and their relaxation rates in the brain can be achieved several times faster than conventional techniques, especially for quantification of glutamate (neuronexcitatory) and lactate (important cancer and stroke biomarker).