The Deleterious Effect of Concomitant Gradient Fields on Diffusion Imaging

through-plane concomitant field phase accrual, for a phantom (squares no correction, triangles corrected) and human brain (circles no correction, diamonds corrected). Dephasing from concomitant gradient fields leads to error in ADC that increases with distance from isocenter (zS = 10cm-superior; zS = 0cm-inferior). FIG 1. Diffusion gradient timing for StejskalTanner (ST; insensitive to concomitant fields) [8], and split-gradient (SG; sensitive to concomitant fields) [6], preparations, where τ is the duration of gradients asymmetric about a refocusing RF pulse. To perform a prospective correction, phase accrual from concomitant fields is refocused by the shaded gradient in the SG case (gradient area is slice dependent).