Multimodal imaging in cancer detection: the role of SPIONs and USPIONs as contrast agents for MRI, SPECT, and PET

Nanomedicine has emerged as a transformative field in medical diagnostics, particularly in cancer detection. Superparamagnetic iron oxide nanoparticles (SPIONs) and ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) have garnered significant attention due to their remarkable properties, making them suitable for use in molecular imaging. These nanoparticles can serve as effective contrast agents for magnetic resonance imaging (MRI) and can also be radiolabeled with various radioisotopes for use in nuclear medicine modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Recent advancements in multimodal imaging systems, such as PET/MRI and SPECT/MRI, have demonstrated the potential of these nanoparticles to combine the strengths of different imaging techniques, allowing for more accurate cancer detection at early stages. MRI provides high spatial and temporal resolution but lacks sensitivity, while PET and SPECT offer high sensitivity with lower resolution. The integration of these modalities allows for enhanced imaging of cancerous tissues. This review discusses the application of radiolabeled SPIONs and USPIONs in dual-modality imaging systems, highlighting their advantages and limitations as contrast agents. The continued development of targeted nanoprobes and the exploration of new multimodal imaging systems offer promising avenues for improving early cancer diagnosis and treatment.