Lanthanide carriers could help define the next generation of biomedical imaging and fast-track the emerging field of theranostics—approaches that link diagnostic imaging with treatment selection, delivery, or monitoring. That’s according to a new review published in Frontiers in Science that maps recent progress and materials innovation across optical, X-ray, and magnetic resonance imaging (MRI). Research teams are increasingly developing lanthanide carriers as dual-function agents that combine imaging with targeted drug delivery, generating new opportunities for theranostic applications, including cancer diagnosis and treatment. The paper highlights how molecular engineering advances and modifications to the surface coatings of lanthanide carriers are now being applied—boosting signal strength to improve accuracy and enhancing biocompatibility to benefit safety. --The article is part of the Frontiers in Science multimedia article hub 'Lanthanide carriers for biomedical imaging'.