1. A method for performing magnetic resonance diffusion imaging of a body showing anisotropic molecular diffusion, comprising: (a) acquiring a sequence of magnetic resonance images of a target body using diffusion-encoding gradient pulses applied along a set of non-collinear orientations sampling a three-dimensional orientation space; (b) estimating, from said sequence of images, a set of space- and orientation-dependent parameters representative of molecular diffusion within said target body; wherein said step of estimating a set of space- and orientation-dependent parameters representative of molecular diffusion within said target body is performed in real time by means of an incremental estimator fed by data provided by said magnetic resonance images; characterized in that said three-dimensional orientation space selectively excludes a set of orientations for which magnetic resonance signal intensity is below a threshold level.