A method of deriving a directional structure from an object dataset is proposed. The object dataset assigns local directions to positions in a multidimensional geometrical space. For example the local directions concern local flow directions in a diffusion tensor magnetic resonance image at least one ‘region of interest’ is selected on the basis of spatial functional information, such as an fMRI image, time correlation of an fMRI image series with a functional paradigm or an anatomical image. These ‘region of interest’ are employed to initialize a fibre tracking to derive the directional structure that represents the nervous fibre system.