A New Volume Selective Sequence for Single-Shot Diffusion-Weighting by the Trace of the Diffusion Tensor

Julien Valette^1,2, Mohamed Ahmed Ghaly², Denis Le Bihan², Franck Lethimonnier²

Diffusion-weighted (DW) spectroscopy is a unique tool for exploring the intracellular micro-environment in vivo. In living systems, diffusion is generally anisotropic, since biological membranes may exhibit anisotropic orientation. In this work, a volume selective DW-sequence is proposed, allowing single-shot measurement of the trace of the diffusion tensor (which does not depend on the gradient orientation relative to the cells). Cross-terms between diffusion gradients and other gradients are cancelled out. In addition, an adiabatic version (similar to the LASER sequence, with diffusion gradients) is derived. Proof of concept is performed on anisotropic tissues by varying tissue orientation and intra-voxel shim.