Objective: To explore the feasibility of sentinel lymph node (SLN) identification by contrast-enhanced ultrasound (CEUS) in pre-operative breast cancer patients and the value of enhancement patterns for diagnosing lymph node metastases and characterising axillary nodal burden.
Methods: 110 consecutive breast cancer patients were enrolled. Before the surgery, microbubbles were injected intradermally. The lymphatic drainage pathway was detected to identify the SLNs. Blue dye and indocyanine green (ICG) fluorescence were used to trace SLNs during the operation. The enhancement patterns of SLNs were recorded and compared with the final pathological diagnosis.
Results: SLN detection rate was 96.4 % of 110 patients, 134 SLNs were detected in total. The sensitivity, specificity, positive-predictive value, negative-predictive value and accuracy of predicting SLNs metastases by CEUS enhancement patterns were 100 %, 52.0 %, 43.4 %, 100 % and 64.9 %, respectively. No metastatic SLNs were presented as homogeneous enhancement. Low nodal burden with 0-2 SLN metastases in 92.5 % nodes presented as heterogeneous enhancement. No enhancement pattern was proved to be SLN metastases in 100 % patients.
Conclusions: CEUS is a feasible approach for SLN identification. CEUS enhancement patterns can be helpful in recognising metastatic SLNs and nodal burden.
Key points: • CEUS is a feasible approach for SLN identification and characterisation. • The enhancement patterns on CEUS can be helpful in recognising metastasised SLNs. • Homogeneous enhancement pattern has the highest negative-predictive value.
Keywords: Breast cancer; Contrast-enhanced ultrasound; Enhancement pattern; Nodal burden; Sentinel lymph node.