Optimization of an implantable magnetic marker for surgical localization of breast cancer

For small, early-stage or otherwise non-palpable breast tumors, surgeons rely on localization technologies to accurately find and remove the tumor tissue during breast conserving surgery. However, current widely accepted localization technologies either use painful and logistically challenging guidewires, or complex radioactive iodine sources. We have developed an implantable magnetic marker, intended to mark the location of a breast tumor, that can be detected during surgery using a clinical handheld magnetic susceptometry system. Here, we report on the development and optimization of this magnetic marker, focusing on the material, shape and various material assemblies. It was found that the effects of magnetic shape anisotropy may decrease localization precision. This can be circumvented by combining multiple isotropic magnetic elements separated from one another. A final optimized prototype was constructed and compared to a commercially available magnetic marker. Finally, the technology was tested in an ex vivo surgical setting on tissue to assess radiological visibility and surgical feasibility. The marker was successfully detected and removed in all ex vivo sessions, and the technology was found feasible.