Patent ID: 8907671

Claim:
A method using an MRI device to extract m diffusion direction(s) μ j from N diffusion-weighted magnetic resonance signals S i of any part of a body that contains water molecules, wherein m is a predetermined positive number m of diffusion direction(s) μ j to be identified in each voxel of said body part with m≧1, comprising exposing by an emitter-receiver the body to a magnetic resonance imaging process, in which N magnetic field diffusion gradients q i , which are non-collinear, are applied by at least one emitter to the entire body part with N being a positive integer ≧2 and the N diffusion-weighted magnetic resonance signals S i are measured by at least one receiver in each voxel of said body part, wherein using a calculator a first component modelling directional variability of water molecules displacements with diffusion direction μ j as mean direction and a second component that models a length variability of the water molecules displacements along said diffusion direction μ j are estimated from the N diffusion-weighted magnetic resonance signals S i for each of the in diffusion direction(s) μ j , wherein a sum of the first component and of the second component is calculated in the calculator for each of the m diffusion direction(s) μ j , wherein, for each of the m diffusion direction(s) μ j , the diffusion direction μ j is extracted in the calculator from the sum being a random vector X j of the water molecules displacements having a probability density function p Xj characterizing the diffusion along the diffusion direction μ j and for respectively the N magnetic field gradients q i applied to said body part.