Whole heart DTI using asymmetric bipolar diffusion gradients

Background Cardiac diffusion weighted imaging (DWI) using a spin echo sequence is challenging because of its high sensitivity to bulk motion. When the displacement or acceleration are constant and coherent but not equal for all spins within a voxel, it will cause signal attenuation due intra voxel de-phasing as an effect of first or second order moment encoding errors. This signal attenuation cannot be distinguished from that originating from diffusion weighting. To compensate for these effects bipolar gradients have been proposed that compensate for first order moment encoding [1]. However, this method will only work under the assumption of a uniform nonaccelerated motion. Therefore, the aim of this study was to develop SE-based cardiac diffusion MRI protocol with second order moment nulling, thus also compensating for acceleration, and to compare its performance to that of Stejskal-Tanner and bipolar gradients waveforms.