MR imaging staging of pelvic lymph nodes

Accurate pelvic nodal staging is important in the workup of many pelvic tumors for assessing prognosis and directing therapy. Advances in diagnostic imaging have played an integral role in the staging of these tumors. Cross-sectional imaging, including MR imaging,however, uses size criteria and morphology to infer malignancy within a node,which is neither sensitive nor specific. This article reviews the normal pelvic nodal anatomy and techniques of conventional MR imaging for optimal nodal evaluation as well as introducing the recent technique of ultra small supraparamagnetic iron oxide(USPIO)-enhanced MR lymphangiography, which uses nodal function rather than structural criteria in assessing for metastatic nodes.