Some aspects provide a method of determining a set of parameter estimates for an incoherent motion model from diffusion-weighted magnetic resonance data of a portion of a biological body. The method comprises determining a first set of parameter estimates for a plurality of voxels associated with one or more images based, at least in part, on the diffusion-weighted magnetic resonance data, determining a second set of parameter estimates by stochastically perturbing the first set of parameter estimates, determining a third set of parameter estimates based, at least in part, on the first set of parameter estimates and the second set of parameter estimates, and determining whether at least one criterion associated with the third set of parameter estimates is satisfied.
