Orthogonal diffusion encoding gradient sequence (ODEG) improves time-dependency measurements in the human brain

Oscillatory gradient dMRI is used to access restricted diffusion at short diffusion times (td). But its clinical application is limited due to the limited gradient strength, leading low b-value and low resolution, and thus is subject to contamination from microcirculation and CSF partial volume. Here we proposed an orthogonal diffusion encoding gradient (ODEG) sequence to improve td–dependency measurements in human brain, by applying a pulse gradient orthogonal to the oscillating gradient to suppress the fast diffusion from microcirculation and free water. The results showed that td-dependency was significantly improved by the ODEG sequence in the hippocampus and cortical gray matter.