Advances of Research on Quasi-paramagnetic Ultrasmall Ferrite Contrast Agents for Magnetic Resonance Imaging

Benefiting from their unique magnetic properties and good biosafety, ferrite nanomaterials are widely used in magnetic resonance imaging (MRI) clinical diagnostics and imaging studies. Quasi-paramagnetic ultrasmall ferrite nanoparticles with the size of less than 5 nm possess high T₁ contrast power and rapid renal clearance, which can help to overcome the drawbacks of traditional gadolinium-based contrast agents with improved safety and efficacy, and are likely to become the next-generation MRI contrast agents. This review summarizes the research progress and challenges of clinical translation of quasi-paramagnetic ferrite nanoprobes as MRI T₁ contrast agents in terms of safety, T₁-T₂ signal enhancement properties, multimodal imaging and integration of diagnosis and treatment.