Multimodal nanoparticles are nanoparticles containing contrast agents for PAT and one or more of luminescence imaging, x-ray imaging, and/or MRI. The multimodal nanoparticles can have a dielectric core comprising an oxide with a metal coating on the core. The particles can be metal speckled. The multimodal nanoparticles can be used for therapeutic purposes such as ablation of tumors or by neutron capture in addition to use as contrast agents for imaging.