Prospective evaluation of MRI artefacts following breast conserving surgery and sentinel lymph node dissection with the magnetic technique.

Introduction: Superparamagnetic Iron Oxide (SPIO) nanoparticles serve as a promising tracer for sentinel lymph node (SLN) detection in breast cancer. Concerns exist regarding artefacts on postoperative Magnetic Resonance Imaging (MRI), especially following breast conservation (BCS).
Materials and Methods: In this prospective observational study, 97 women with DCIS or invasive breast cancer underwent BCS and SLN detection with peritumoral SPIO injection administered up to four weeks before surgery. Postoperatively, patients were followed with MRI and mammograms, and imaging outcomes were evaluated by four, independent breast radiologists, blinded to clinical data, using a predefined, standardized questionnaire.
Results: In 97 patients included, there was inter-rater discordance in the prevalence of "any artefact" (range: 24.1-74.4 %; weighted average: 32.4 %) and "SPIO specific artefact" (range: 12.0-49.4 %; weighted average: 20.9 %). The median area of "any artefact" was 9.24 cm ² (iqr 4.72, 15.50) and SPIO specific artefact 9.88 (iqr 5.32, 15.5). Likert scores indicated higher difficulty interpreting MRI if artefacts were present (OR: 2.295, 95 % CI 1.028, 5.123; p = 0.043), but this was reduced if intravenous contrast was administered (OR: 0.177, 95 % CI 0.091, 0.342; p < 0.001). Multivariable analysis identified free-hand SPIO administration as a risk factor (OR 8.929, 95 % CI 2.849, 27.778; p < 0.001). All six patients with local recurrence were successfully diagnosed on MRI by all raters.
Conclusion: This prospective cohort study suggests that a targeted peritumoral SPIO injection can result in the removal of SPIO during lumpectomy and address the concerns for artefacts on postoperative MRI follow-up, in the selected patients that MRI may be warranted.
Competing Interests: Conflicts of interest Dr Karakatsanis reported receiving institutional grants from Endomag and honoraria from Elsevier, Pfizer, AstraZeneca, KUBTEC and Resitu AB outside the scope of the submitted work. No other disclosures were reported. Dr Karakatsanis is Deputy Editor-in-Chief for the European Journal of Surgical Oncology and was not involved in the editorial review or the decision to publish this article.
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