Table 1.

Parameters to quantify vascularization

Model independent direct 3D parameters
Vessel density (vessel volume per total volume)	VV/TV
Vessel surface	VS
Vessel thickness	V.Th 3D
Rod-model based parameters
Vessel thickness	$V.T{h}_{2D}=4/\left(\frac{\mathit{VS}}{\mathit{VV}}\right)$
Vessel spacing	$V.S{p}_{2D}=V.T{h}_{2D}\cdot \left(\sqrt{\frac{4/\pi \cdot \mathit{TV}}{\mathit{VV}}}-1\right)$
Vessel number	$V.N_{2D}=\sqrt{\left(\frac{4}{\pi }\cdot \frac{\mathit{VV}}{\mathit{TV}}\right)/V.T{h}_{2D}}$