Imaging of iron oxide nanoparticles by MR and light microscopy in patients with malignant brain tumours

In malignant tumours, ferumoxtran may show areas of enhancement, even with a 0.15 T intraoperative MR, that do not enhance with gadolinium. Ferumoxtran-enhancing lesions have persistent increased T1 signal intensity for 2-5 days, which may provide advantages over gadolinium for postoperative imaging. Histochemistry for iron shows uptake of ferumoxtran in reactive cells (astrocytes and macrophages) rather than tumour cells.