The rare earth oxide particles and especially its use in imaging

The present application concerns multimodal composite products for imaging, in particular for diagnostic imaging, and optionally for therapy, in particular composite products which are capable of being used as contrast agents, in particular in magnetic resonance imaging (MRI), and/or in imaging techniques such as, for example, in optical imaging, in the optical detection of oxidants, in positron emission tomography (PET), in tomodensitometry (TDM) and/or in ultrasound imaging, and optionally simultaneously for use in therapy. These products are based on a particle comprising or consisting of a portion provided with a contrast agent activity and/or a paramagnetic activity, and a portion provided with a luminescent activity and optionally an oxidant detection activity.