Revealing Diffusion Frequency-Dependence in Surface-to-Volume Ratio limit using OGSE sequence on the Connectome 2.0 Scanner

Motivation: Diffusion frequency-dependence offers a direct probe to tissue microstructure at diffusion length scale. Oscillating-gradient-spin-echo (OGSE) sequence provides very short effective diffusion time and length for evaluating fine structures but poses challenges in simultaneously achieving high diffusion-weighting and high frequency on human scanners. Goal(s): To validate the potential of OGSE sequences on the high-gradient-performance Connectome 2.0 scanner. Approach: We measured diffusivity frequency-dependence (30-100Hz) in an anisotropic solid-fiber phantom on Connectome 2.0 and estimated surface-to-volume ratio and fiber radius, whose value was corrected for non-ideal cosine-OGSE waveform. Results: Estimated fiber radius matched the ground-truth (error<5%), demonstrating the potential of in vivo microstructural imaging using OGSE. Impact: We performed diffusion frequency-dependence using oscillating-gradient-spin-echo (OGSE) sequence (≤100Hz) and accurately estimated fiber radius in an anisotropic fiber phantom on the Connectome 2.0 human scanner, demonstrating the potential of in vivo microstructural imaging using OGSE.