Fig. 3.

Benign and metastatic lymph nodes on ultrasmall superparamagnetic iron oxide (MION [monocrystalline iron oxide nanoparticle]-47)-enhanced MR imaging in three rabbit VX2 tumor models.

A. T2^*-weighted MR image obtained 24 hours after intravenous administration of MION-47 (2.6 mg of iron per kilogram of body weight) shows homogeneous dark signal intensity of benign left paraaortic lymph node (arrow).

B. T2^*-weighted MR image obtained 24 hours after intravenous administration of MION-47 (2.6 mg of iron per kilogram of body weight) shows focal high signal intensity region (arrowhead) in right paraaortic lymph node (arrow), which was proven to be metastatic focus by histopathology.

C. T2^*-weighted MR image obtained 24 hours after intravenous administration of MION-47 (2.6 mg of iron per kilogram of body weight) shows malignant right paraaortic lymph node (arrow), which was totally replaced with metastatic tissue.