An imaging nanoparticle comprising a plant virus particle having an interior surface and an exterior surface, an imaging agent that is linked to the interior and/or exterior surface, and a layer of biocompatible mineral such as silica coated over the exterior surface, is described. The imaging nanoparticle can be used in method of generating an image of a tissue region of a subject, by administering to the subject a diagnostically effective amount of an imaging nanoparticle and generating an image of the tissue region of the subject to which the imaging nanoparticle has been distributed.