An adapted protocol for magnetic localisation of nonpalpable breast cancer lesions and sentinel lymph nodes using a magnetic seed and superparamagnetic iron oxide tracer.

BACKGROUND: Localisation techniques for nonpalpable breast cancer lesions and sentinel lymph node biopsy (SLNB) are associated with several drawbacks. A complete magnetic technique using magnetic seeds and superparamagnetic iron oxide tracer could be an interesting alternative. This study describes a clear protocol and the results of a combined magnetic approach. METHODS: From August 2021 to February 2022 40 patients undergoing breast conserving surgery with SLNB were eligible for inclusion. Localisation was performed under ultrasound or stereotactic guidance, 1 week before surgery. Subsequently, 1 ml of tracer was injected at least 4 cm away from the tumour. Technetium-99m (99m Tc) was injected 1 day before surgery as control procedure. Outcomes were SLNB time, a number of nodes detected with magnetic tracer including comparison with 99m Tc, a success rate of malignant lesion detection and pathological margin assessment. RESULTS: In total, 40 procedures were performed on 39 patients. A median of one node was retrieved. Sentinel nodes were retrieved using MagTrace® with a 92.5% detection rate compared to 99m Tc. Wide local excision under magnetic guidance was successful in 35 cases. CONCLUSIONS: This paper describes a combined magnetic approach for breast-conserving surgery and SLNB. An adapted protocol is described and could be used for implementation.

Sentinel lymph node mapping with superparamagnetic iron oxide for melanoma: a pilot study in healthy participants to establish an optimal MRI workflow protocol.

BACKGROUND: Current pre-operative Sentinel Lymph Node (SLN) mapping using dual tracing is associated with drawbacks (radiation exposure, logistic challenges). Superparamagnetic iron oxide (SPIO) is a non-inferior alternative for SLN mapping in breast cancer patients. Limited research has been performed on SPIO use and pre-operative MRI in melanoma patients to identify SLNs.  METHODS: Healthy participants underwent MRI-scanning pre- and post SPIO-injection during 20 min. Workflow protocols varied in dosage, massage duration, route of administration and injection sites. The first lymph node showing a susceptibility artefact caused by SPIO accumulation was considered as SLN. RESULTS: Artefacts were identified in 5/6 participants. Two participants received a 0.5 ml subcutaneous injection and 30-s massage, of which one showed an artefact after one hour. Four participants received a 1.0 ml intracutaneous injection and two-minute massage, leading to artefacts in all participants. All SLNs were observed within five minutes, except after lower limb injection (30 min). CONCLUSION: SPIO and pre-operative MRI-scanning seems to be a promising alternative for SLN visualization in melanoma patients. An intracutaneous injection of 1.0 ml SPIO tracer, followed by a two-minute massage seems to be the most effective technique, simplifying the pre-operative pathway. Result will be used in a larger prospective study with melanoma patients. TRIAL REGISTRATION: ClinicalTrials.gov (NCT05054062) - September 9, 2021.