Diffusion MRI is a unique imaging modality suitable for probing tissue microstructure. Unlocking the full potential of diffusion MRI for microstructural imaging requires an adequate diffusion encoding method in terms of diffusion time and gradient strength. dMRI Diffusivity is typically interpreted as a rough measure of the cell density and extracellular water fraction. However, diffusivity and other commonly used dMRI metrics remain non-specific markers, because a diffusion measurement at a fixed diffusion time is affected by multiple factors. The complex microstructural features of tumors and the brain can be probed by adequate sampling of the multi-dimensional space of diffusion encoding.
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