Table 1.

The used composite multi-compartment models, their compartments (divided into intra-, extra-axonal, and isotropic) and total number of parameters.

Model	Restricted (intra-cellular) compartments	Hindered (extra-cellular) compartments	Isotropic compartments	Number of parameters	Acquisition requirements
Tensor	–	Tensor	–	7	b < 1.5·106s/m2
Ball&Sticks _in[n]	Stick (n-times)	–	Ball	1+3n	–
NODDI	NODDI_in	NODDI_ex	Ball	6	≥2 b-values / shells
CHARMED _in[n]	CHARMED _in (n-times)	Tensor	–	7+4n	≥2 b-values / shells, $b_{\text{max}}\ge 4.0·10^{6}s/m^2$

For an overview of the individual compartments, please see Table 2.