Use of Superparamagnetic Iron Oxide Particles in Sentinel Node Biopsy-Evaluation of Its Effects on Breast MRI, Full-Field Digital Mammography, and Contrast-Enhanced Mammography

Upon surgical removal of solid tumors in patients with breast cancer, the sentinel lymph nodes are mostly concomitantly removed as this is the first site to which tumor cells metastasize. To identify the sentinel lymph nodes, superparamagnetic iron oxide (SPIO) particles can be employed, a method that has several advantages over the classical tracer with radioisotopes. However, one downside of SPIO particles is the formation of artifacts on magnetic resonance imaging (MRI) of the breast. In a previous study, we investigated if lowering the dose of these particles from 2 to 1 mL would prevent the occurrence of these artifacts. In a study of 14 patients, radiologists do not observe any artifacts on the full-field digital mammography and contrast-enhanced mammography images, contrary to breast MRI images, in which case artifacts are observed on all images. Hence, lowering the dose from 2 to 1 mL SPIO particles did not change the outcome of the breast MRI images. In this article, based on these results, we discuss the origins of these artifacts from a mathematical and physical point of view.