TABLE I.

Summary of Equations

Measures	Conventional 3D FT	New direct approach
Po	$Po=P(\overrightarrow{R}=0,\Delta )$	$Po\approx {\int }_{-q_{\max }}^{q_{\max }}{E}_{\Delta }\left(\overrightarrow{q}\right)d\overrightarrow{q}$
MD = MSD/6Δ	$MSD=\int \int \int P(\overrightarrow{R},\Delta )\cdot {\overrightarrow{R}}^2{d}^3\overrightarrow{R}$	MSD = Var{FT1D[GM(qr,S)]}
ODF	$ODF({\theta }_R,{\phi }_R)={\int }_{\rho }P({\theta }_R,{\phi }_R,\rho )d\rho$	ODF(θR,φR) = MQθR, φR (qr = 0). where MQθR,φR is the marginal function of the q-space signals along direction (θR, φR).