Super-resolution ultrasound imaging of intranodal lymphatic sinuses for predicting sentinel lymph node metastasis in breast cancer: a preliminary study.

Objectives: Accurate preoperative localization and characterization of sentinel lymph nodes (SLNs) is vital in breast cancer management. The application of super-resolution ultrasound (SRUS) imaging to visualize intranodal lymphatic sinuses for the prediction of SLN metastasis has yet to be investigated. The study aimed to assess the value of SRUS imaging of intranodal lymphatic sinuses in predicting SLN metastasis in breast cancer patients.

Methods: A total of 154 SLNs from 143 patients with breast cancer were prospectively included. All patients underwent conventional US of axillary lymph nodes and SRUS imaging of lymph sinus by percutaneous microbubble injection. Qualitative and quantitative analysis were performed for SRUS imaging, with qualitative analysis focusing on identifying perfusion defects and quantitative analysis including parameters such as lymphatic sinus density, sinus diameter, sinus distance, and lymph flow velocity. The areas under the receiver operating characteristic curve (AUC), sensitivity, and specificity were calculated for conventional US, SRUS, and combined conventional US and SRUS.

Results: Among the 154 SLNs, 73 were metastatic and 81 were reactive. In predicting metastatic SLNs, the AUC for SRUS (0.824; 95% CI: 0.761-0.888) was significantly higher than that for conventional US (0.661; 95% CI: 0.596-0.726) (p < 0.001). The combination of SRUS and conventional US achieved the highest AUC (0.844; 95% CI: 0.785-0.904), which was significantly higher than conventional US alone (p < 0.001), but not significantly different from SRUS alone (p = 0.2).

Conclusion: Imaging lymphatic sinuses by SRUS has the potential to predict metastatic SLNs in patients with breast cancer.

Key points: Question Super-resolution ultrasound (SRUS) used for visualizing intranodal lymphatic sinuses for the prediction of sentinel lymph nodes (SLNs) metastasis has yet to be investigated. Findings Microlymphatic circulation of SLNs were imaged by SRUS at ten microns scale. SRUS showed better performance for predicting metastatic SLNs than conventional ultrasound. Clinical relevance SRUS is a reliable tool to image lymphatic sinuses and characterize metastatic SLNs in patients with breast cancer. It helps diagnosis of lymph node status and clinical decision-making of breast cancer.