Theoretical description of modern 1 H in Vivo magnetic resonance spectroscopic pulse sequences

This article reviews the most commonly used modern sequences designed to confront the two major challenges of in vivo magnetic resonance spectroscopy (MRS): spatial localization and metabolic specificity. The purpose of this review article is to provide a deeper and clearer understanding of the underlying mechanisms by which all modern MRS sequences operate. A descriptive explanation, consistent pulse sequence diagram, and theoretical concepts of the measured signal are given for five spatial localization sequences and three modules designed to increase metabolic specificity. Cross-sequence comparisons, including potential modifications for estimating quantitative measures like spin-lattice relaxation time T , spin-spin relaxation time T , and diffusion coefficients are briefly discussed. Level of Evidence: 5 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2020;51:1008-1029.