Background,Motivation and Objective Sentinel lymph nodes(SLNs) are the first draining lymph nodes while the metastatic cancer cells are spreading.A noninvasive imaging modality for SLN identification with fine needle aspiration biopsy(FNAB) would be beneficial for staging the axillary lymph nodes without surgical intervention.Recently,photoacoustic imaging has shown its feasibility of SLN mapping.However,it is not available for clinical use yet,and involves laser safety issues.MRI has been tried with superparamagnetic iron oxide nanoparticles(SPIOs) for SLN imaging.Because of its high cost and low imaging rate,MRI is not a good solution for SLN FNAB.