1. A system for imaging the structure of at least a selected portion of an object substantially composed of at least one of diamagnetic and paramagnetic materials, said system including: means applying a magnetic field of known strength, orientation and time dependence to the at least selected portion of said object: magnetometer means measuring local perturbations in the applied magnetic field indicating local susceptibility of said object at an array of locations across said at least selected portion of said object to generate an array of perturbation signals; adjusting means adjusting the angular orientation of at least one of said magnetic field, said object, and said magnetometer means relative to the others to generate a plurality of relative orientations, said magnetometer means including means measuring local perturbations in the applied magnetic field at an array of locations for each of said plurality of relative orientations to produce a plurality of arrays of perturbation signals; processing means processing by matrix decomposition techniques said plurality of arrays of perturbation signals to generate at least one array of signals representing a map of local susceptibilities at selected sites in said at least selected portion of said object; and means presenting said array of local susceptibilities at the selected sites in the at least selected portion of said object.