Impact of an ultra-low dose of superparamagnetic iron oxide on postoperative breast MRI artifacts and skin discoloration in patients with breast cancer

Background: Superparamagnetic iron oxide (SPIO) nanoparticles are non-inferior as a tracer for sentinel lymph node biopsy (SLNB) detection in breast cancer patients compared to the standard radioactive tracer (technetium-99m, Tc 99m ) with or without blue dye (Patent blue V ® , BD). Sentinel lymph node (SLN) detection has been successful using an ultra-low dose of 0.1 mL SPIO injected intradermally in patients with breast cancer, and this study aims to assess the potential reduction of SPIO-related skin discoloration and breast magnetic resonance imaging (MRI) artifacts at 6 and 12 months after breast-conserving surgery using the ultra-low dose of SPIO. Method: Skin discoloration and MRI artifact were pre-planned endpoints in the prospective MAGSNOW feasibility study. MRI follow-ups were scheduled 6 and 12 months after surgery, and MRI artifacts were classified into six grades. SPIO-induced skin discoloration was assessed at baseline, 1, 6, and 12 months by photography. Results: Thirty-six patients had 6- and 12-month MRI follow-up performed, revealing no MRI artifacts impairing breast assessment. At 12 months, 75.0% (27/36) of the patients had minimal MRI artifacts, primarily in the subcutaneous tissue, or <5 mm in the fibro-glandular tissue. At 12 months, 54% (27/50) of the patients had a skin discoloration with a median area of 0.79 cm 2 (interquartile range (IQR) 0.14–1.41). Conclusion: An ultra-low dose of SPIO may offer a solution to the concerns of MRI artifacts and skin discoloration associated with the present recommended dose of 1–2 mL of SPIO.