3D diffusion MRI with twin-navigator-based GRASE for cortical gray matter time-dependency measurements in the human brain

3D oscillating gradient sequences enable diffusion measurement at short diffusion-time (td), but it suffered from low resolution and low SNR in clinical systems, and thus, the td-dependency in complex structures, such as cortical gray matter, was not characterized. Here we proposed a twin-navigator-based 3D oscillating gradient diffusion-weighted gradient spin-echo sequence for high-resolution whole-brain td–dMRI acquisition. We demonstrated that different cortical regions exhibited distinct td-dependency patterns with different diffusion dispersion exponent (θ) based on the power-law. We found θ was greater than 0.5 with the highest dispersion in the pre- and post-central cortex and lowest value in the frontal region.