FIGURE 1.

A schematic overview of 1D (piecewise) versus 2D (dynamic) fitting schemes for a fictitious multi‐echo MRS experiment designed to estimate the T₂. (Top) In 1D fitting, data is initially fit to a spectral model to extract the relevant spectral parameters, ${\theta }^{(\nu )}$, such as the area (or amplitude) of each spectral peak or metabolite basis function. These are then fit to the relevant temporal model to extract the relevant temporal parameters, ${\theta }^{(t)},$ which for a multi‐echo experiment include T₂. (Bottom) In 2D fitting, the entire spectral‐temporal dataset is fit simultaneously to a spectral‐temporal model. Such fitting simultaneously furnishes all spectral and temporal parameters—for example, T₂ for a multi‐echo experiment