Abstract:

Objective  To investigate whether subcutaneous contrast-enhanced ultrasound can identify the features of sentinel lymph node (SLN) and the value for identifying malignant and benign axillary lymph nodes. Methods  The rabbit model of breast cancer was established under sterile condition. Contrast enhanced agent was injected around the breast tumor subcutaneously after tumors were inoculated for six weeks. The features of lymph nodes were identified and marks were made on the skin. Activated nono-carbon particles were injected after 30 min. Results of contrast-enhanced ultrasound of SLNs were observed. Malignant and benign SLNs were identified and marks were made on the skin. Rabbits were sacrificed after observation and tumors were harvested. The axillary lymphadenectomy was conducted and pathological examination was performed for all lymph nodes. Results  A total of 16 tumors were found in 20 breasts of 10 rabbits and 11 of them metastasized and 5 of them did not metastasize. The subcutaneous contrast-enhanced ultrasound detected 16 of 17 SLNs (94.12%). The sensitivity, specificity, PPV, NPV, and accuracy of subcutaneous contrast-enhanced ultrasound for diagnosing malignant lymph nodes were 80.0%, 71.42%, 80.0%, 71.42%, and 76.47% respectively. The P value between contrast-enhanced ultrasound and differential test of pathological diagnosis (McNemar test) for diagnosing malignant SLNs was 0.688. Two methods were consistent with Kapp=0.514 and P=0.034. Conclusion  Subcutaneous contrast-enhanced ultrasound is valuable for diagnosing malignant SLNs of breast cancer and can reveal the metastasis of axillary lymph nodes.

Key words: sentinel lymph node, subcutaneous contrast-enhanced ultrasound, axillary lymph nodes metastasis