TbF3 nanoparticles as dual-mode contrast agents for ultrahigh field magnetic resonance imaging and X-ray computed tomography

Considering the development of magnetic resonance imaging (MRI) under ultrahigh magnetic field (> 3 T), the exploration of novel contrast agents (CAs) for ultrahigh field MRI is urgently needed. Herein, we report polyethyleneimine (PEI)-coated TbF3 nanoparticles (NPs), which were synthesized by a facile solvothermal method, as potential dual-mode CAs for ultrahigh field MRI and X-ray computed tomography (CT). Owing to their strong paramagnetism, the TbF3 NPs showed excellent transverse relaxivity (395.77 mM(-1)center dot s(-1)) and negligible longitudinal relaxivity under an ultrahigh magnetic field (7 T) with a great potential as a T (2)-weighted MRI contrast agent. Furthermore, by comparison with the clinically used CT CAs (iohexol), the TbF3 NPs showed superior X-ray attenuation ability. The practical application for T (2)-weighted MRI and CT imaging was demonstrated with an animal model. Moreover, cell cytotoxicity and in vivo toxicity assessments implied the low toxicity of TbF3 NPs. In summary, the above results indicate that TbF3 NPs are promising candidates for ultrahigh field MRI and CT dual-mode imaging.