Radiolabeled Iron Oxide Nanomaterials for Multimodal Nuclear Imaging and Positive Contrast Magnetic Resonance Imaging (MRI): A Review

Iron oxide nanoparticles (IONP) have been hailed as potential game-changers in biomedical imaging owing to their biocompatibility and size-dependent properties. One area where IONP has shown particular promise is magnetic resonance imaging (MRI), which traditionally uses superparamagnetic nanomaterials to produce negative contrast that darkens the tissues where nanoparticles accumulates. Unfortunately, this hypointense signal is a major drawback for clinical applications because it can make it difficult to identify the accumulated probes. As a result, researchers are exploring alternative options that can incorporate the advantages of IONP while also possessing valuable properties for molecular imaging. To achieve this goal, the most effective method involves not only utilizing positive contrast in MRI applications but also combining IONP with the unparalleled sensitivity of nuclear imaging techniques, for example, using radioisotopes to create PET/(T1)MRI multimodal probes. To create such probes, various factors must be considered, including the radiolabeling strategy employed and overall complexity of the final nanoprobe. These nanoradiomaterials offer novel possibilities that span beyond the molecular imaging field, showing potential for the development of radiopharmaceuticals and theranostics.