Minimizing Diffusion Encoding of Slice Selection in Stimulated Echo Imaging

Purpose: Diffusion weighted imaging (DWI) using very high b-values and long diffusion times (Δ) typically uses the stimulated echo (STE) in order that large diffusion encodings can be produced without incurring excessive T2-related signal loss. For long Δ a significant bias can be introduced through the diffusion encoding effect of the slice selection gradients that are typically used in multi-slice implementations of the STE scheme. Compensation of this effect has recently been achieved by adjustment of the prescribed diffusion encoding gradients [1], but the nature of the adjustment is specific to the exact choice of experimental parameters. In this report we show that the effect can simply be minimized through reduction of the diffusion encoding effect of the slice selection gradients themselves, as often implemented in STEAM MRS, thus providing a more straightforward method for maintaining suitable control over the applied diffusion encoding scheme.