MR imaging of tumor-associated macrophages.

Tumor associated macrophages (TAMs) in breast cancers foster several aspects of tumor progression and metastasis, and represent a biomarker associated with an unfavorable clinical outcome. As new therapeutic agents selectively targeting leukocytes enter the clinic whose mechanism of action involves diminishing macrophage infiltration or presence in tumors, it becomes increasingly important to identify those tumors heavily infiltrated by TAMs, as well as monitoring TAM response to therapy. MR imaging with iron oxide nanoparticles enables noninvasive quantification of TAMs in tumors, and thus, provides an easily accessible ex vivo assessment of TAMs for prognosis and related treatment decisions.