Abstract： Objective To explore the application feasibility of contrast-emhanced ultrasound (CEUS) plus methylene blue in sentinel lymph node biopsy (SLNB) for breast cancer and determine the ultrasonographic features of sentinel lymph node (SLN).Methods The microbubbles of SonoVue were injected subcutaneously and intradermally into tumor side of areola.The images were observed to record the size,number,lymphatic door,aspect ratio,enhanced time and enhanced mode of SLN.Methylene blue was injected into SLN under the guidance of ultrasound.The marked SLNs were dissected for pathological examinations.Based upon the results,the specimens were divided into SLN metastasis and SLN nonmetastasis groups.Results A total of 34 breast cancer patients were recruited.Among them,SLN was detected preoperatively in 31 patients by CEUS and the rate was 91.2％.And the postoperative results showed that 14 were confirmed positive (metastasis group) and 17 negative (non-metastasis group).The sensitivity,specificity,accuracy and false negative rate of CEUS for detecting SLNs were 93.3％ (14/15),100％(16/16),96.8％ (30/31) and 6.7％ (1/15) respectively.The model of stepwise regression analysis showed that lymphatic door,aspect ratio and enhanced mode were helpful to differentiate SLN metastasis and SLN nonmetastasis groups.Conclusions SLNB under the guidance of CEUS plus methylene blue offer prompt and accurate localization with a lower cost.It may enhance the detection rate of SLNB in breast cancer.