Impact of low dose superparamagnetic iron oxide tracer for sentinel node biopsy in breast conserving treatment on susceptibility artefacts on magnetic resonance imaging and contrast enhanced mammography

Residual particles of superparamagnetic iron oxide (SPIO) tracer, used for sentinel node biopsy, cause susceptibility artefacts on breast Magnetic Resonance Imaging (MRI). We investigated the impact of these artefacts on the imaging quality of MRI and explored whether contrast-enhanced mammography (CEM) could be an alternative in the follow-up of breast cancer patients. Data on patients’ characteristics, injection site, presence, size (mm) of artefacts on full-field digital mammography (FFDM)/CEM, MRI after 1 ml SPIO was recorded. Image quality scored by two breast radiologists using a 4-point Likert system: 0: no artefacts 1: good diagnostic quality 2: impaired but still readable 3: hampered clinical assessment. Continuous variables reported as means and standard deviations (SD), categorical variables as count and percentage. On FFDM/CEM, performed 13 months postoperatively, no iron SPIO particles were detected, with a Likert score of 0. In all MRI (100%) images, executed at 16.6 months after SPIO injection, susceptibility artefacts at the injection sites i.e., retroareolair and lateral quadrant were observed with a mean size of 41.9 ± 9.8 mm (SD) by observer 1, and 44.8 ± 12.5 mm (SD) by observer 2, independent of the injection site. Both observers scored a Likert score of 2: locally impaired on all MRI images and sequences. Even 1 ml SPIO tracer used for sentinel node procedure impairs the evaluation of breast MRI at the tracer injection site beyond one year of follow-up. No impairment was observed on FFDM/CEM, suggesting that CEM might be a reliable alternative to breast MRI if required. •Even after injection of 1 ml of superparamagnetic iron oxide (SPIO) tracer, iron remnants stay behind in the breast tissue.•Iron remnants grossly disturb all breast MRI images (100%) at the tracer injection site.•No impact was seen on the images of full-field digital/contrast-enhanced mammography (CEM).•CEM could be valuable alternative if additional imaging is needed in the follow-up of breast cancer.