Table 1.

Microstructural parameters of the diffusion model. All diffusion coefficients are in $\mu m^2/ms$.

Parameter	Description	Range
$s_{iso}$	Signal fraction for isotropic (free water) diffusion compartment	$[0,1]$
$s_{in}$	Signal fraction for intra-axonal compartment	$[0,1]$
$s_{ex}$	Signal fraction for extra-axonal compartment	$[0,1]$
$d_{iso}$	Isotropic (free water) diffusivity coefficient	$[0,\infty ]$
$d_{in,a}$	Parallel diffusivity for the intra-axonal compartment	$[0,\infty ]$
$d_{ex,a}$	Parallel diffusivity for the extra-axonal compartment	$[0,\infty ]$
$\tau$	radial to axial diffusivity ratio for the extra-axonal compartment	$[0,1]$
$ODI$	Orientation dispersion index	$[0,1)$