Pre-Excitation Gradients for Eddy Current Nulled Convex Optimized Diffusion Encoding (Pre-ENCODE)

Motivation: Eddy current-induced image distortions in DWI require either tedious image-based corrections or time inefficient pulse sequence acquisitions that increase the minimum echo time (TEmin) and limit SNR. Goal(s): Pre-excitation gradients for eddy current-nulled convex optimized diffusion encoding (Pre-ENCODE) was used to mitigate eddy current-induced image distortions without increasing TEmin. Approach: Simulations, phantoms, and volunteer DWI with monopolar (MONO), eddy current-nulled convex optimized diffusion (ENCODE), and Pre-ENCODE were used to evaluate TEmin, eddy current-induced image distortions, and ADC. Results: Pre-ENCODE offers shorter TEmin compared to MONO and ENCODE as well as reduced eddy current-induced image distortions and more accurate ADC values compared to MONO. Impact: Pre-ENCODE reduces eddy current-induced image distortions by incorporating an additional pre-excitation gradient. Pre-ENCODE provides a shorter TEmin, increased SNR, improved image registration, and more accurate ADC quantification compared with conventional DWI encoding techniques.