Abstract #5114

Echo-time dependence of microscopic fractional anisotropy using single-shot spiral encoding and free water elimination

Farah Mushtaha^1,2, Paul Dubovan ^1,2, Ali Khan^1,2,3,4,5, and Corey Baron^1,2,3,4,5

¹Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada, ²Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University, London, ON, Canada, ³The Brain and Mind Institute, Western University, London, ON, Canada, ⁴School of Biomedical Engineering, Western University, London, ON, Canada, ⁵Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON, Canada

Synopsis

Keywords: Microstructure, Diffusion/other diffusion imaging techniques

Motivation: Understand echo time (TE) dependence of microscopic fractional anisotropy (µFA) in white matter (WM), cortical grey matter (GM), and deep GM.

Goal(s): Measure µFA at varying TEs and observe the trends in WM, cortical GM, and deep GM.

Approach: Healthy volunteers were scanned with dMRI at 3T using a spiral imaging sequence with linear tensor encoding and spherical tensor encoding. µFA was calculated with and without free water elimination (FWE).

Results: Linear regression fitting showed a downward trend in µFA in cortical GM and deep GM with increasing TE, both with and without FWE.

Impact: We observed reducing µFA with increasing TE in grey matter for the first time, which was enabled by a spiral readout that greatly reduced the minimum TE (~20 ms). This TE-dependence can potentially be exploited for improved microstructural modelling.

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