Hospital System Adoption of Magnetic Seeds for Wireless Breast and Lymph Node Localization

As an alternative to traditional wire localization, an inducible magnetic seed system can be used to identify and remove nonpalpable breast lesions and axillary lymph nodes intraoperatively. We report the largest single-institution experience of magnetic seed placement for operative localization to date, including feasibility and short-term outcomes.

Patients who underwent placement of a magnetic seed in the breast or lymph node were identified from July 2017 to March 2019. Imaging findings, core needle biopsy, surgical pathology results, and type of surgery were collected. Outcomes included procedural complications, magnetic seed and biopsy clip retrieval rates, and need for additional surgery.

A total of 842 magnetic seeds were placed by nine radiologists in 673 patients and retrieved by six surgeons at six operative locations. The majority of breast lesions were malignant (395/659, 59.9%); 136 seeds were placed for lymph node localization. The overall magnetic seed retrieval rate was 98.6%, whereas the biopsy clip retrieval rate was 90.9%. Only six patients (0.7%) experienced a complication from magnetic seed placement. Reexcision was performed in 15.2% of patients with breast cancer; 9.6% of benign/high risk lesions were upgraded to malignancy at surgical excision.

The magnetic seed technique is safe, effective, and accurate for localization of breast lesions and lymph nodes, and importantly uncouples surgery from the localization procedure. The high magnetic seed retrieval rate and low reexcision rate may reflect the accuracy of magnetic marker placement as a "second chance" localization procedure, especially in cases with biopsy clip migration.