Local Optimization of Diffusion Encoding Gradients Using a Z-Gradient Array for Echo Time Reduction in DWI

Spatial dependency of the gradient fields can be dynamically optimized using a gradient array coils driven by independent gradient amplifiers. Such dynamic optimization allows to maximize gradient strengths inside a target volume such as slice rather than the entire VOI. Gradient linearity error constraints can also be relaxed to obtain higher gradient strengths. Higher gradient strength can be utilized as diffusion gradients for shorter diffusion durations and TEs for fixed b-value, which increases the SNR of the DWI. Nine channel z-gradient array is used to create optimized gradient fields, which lead to 50% reduction of TE in phantom experiments.