Superparamagnetic iron oxide nanoparticles: nodal metastases and beyond.

Superparamagnetic iron oxide (SPIO) nanoparticles are unique MR contrast agents and are of great interest for their multiple potentials. SPIO nanoparticles have a higher diagnostic accuracy for detecting metastatic lymph nodes than conventional MR studies, particularly in head and neck. The impact of this unique MR contrast agent on treatment decision of patients with head and neck cancer needs to be investigated in comparison with contrast-enhanced CT. As MR technology advances, the accuracy of SPIO nanoparticles for detection of metastasis certainly improves; thus, 1 day we may be able to reliably detect metastases in stage N0 patients, so that treatment strategy is established for each individual patient. This article presents physiologic properties of SPIO, technical considerations and diagnostic accuracy for imaging with SPIO, and other potential applications of SPIO agents.