Sentinel lymph node biopsy (SLNB) has become the standard procedure for the axillary staging in early breast cancer patients

using the radioisotope combined with blue dye. However

the extensive application of SLNB has been restricted by the poor specificity and access issue of the traditional tracer. Many novel sentinel lymph node tracers have been produced accordingly. The indocyanine green is cheap and safe to use. However

the poor penetrating power and targeting power might become the bottleneck limiting its wide application. The contrast-enhanced ultrasonography can be used to dynamically visualize lymphatic vessels and lymph nodes in real time

whereas the success rate and accuracy are relatively low. The superparamagnetic iron oxide techniques are easy to operate and could avoid iatrogenic radionuclide pollution with good application prospects.