Evidence for Microscopic Diffusion Anisotropy in Spinal Cord Tissue Observed with DWV Imaging on a Whole-Body MR System

Double-wave-vector diffusion-weighting (DWV) experiments [1] can be used to characterize local spin diffusion in tissue. They have been successfully applied to detect restricted diffusion [2] and diffusion anisotropy present on a microscopic level in macroscopically isotropic samples [3]. Thereby, the additional degree of freedom, the angle between the two wave vectors, is explored by rotating the direction of the diffusionweighting gradients of the two periods relative to each other. However, the experimental demonstration of the anisotropy effect that yields a reduced signal for orthogonal wave vectors compared to parallel or antiparallel wave vectors, has been limited to high-field NMR spectrometers with maximum gradient amplitudes of 300mT/m and above [3,4]. In this work, evidence for the detection of the anisotropy effect on a standard wholebody MR system (maximum gradient amplitude 40mT/m) is provided.