Combining Contrast-Enhanced Ultrasound with Methylene Blue for Detection of Sentinel Lymph Nodes in Early Breast Cancer

<b>Aims/Background</b> Sentinel lymph nodes (SLNs) are an important prognostic factor for breast cancer patients, but traditional axillary lymph node dissection methods have many complications, while sentinel lymph node biopsy has been developed as a better method. This study aimed to evaluate the efficiency of combining contrast-enhanced ultrasound (CEUS) with methylene blue for identifying SLNs in early-stage breast cancer patients. <b>Methods</b> This retrospective study included clinical data from 163 female patients with lymph node-negative and T1-2 early breast cancer admitted to China-Japan Friendship Hospital between August 2022 and November 2023. All patients received a periareolar injection of SonoVue followed by ultrasonography to identify SLNs. The methylene blue was used to detect SLNs during the surgery, and the patients underwent sentinel lymph node biopsy. We compared the methylene blue method with combined CEUS and methylene blue to identify the number of SLNs per patient. Furthermore, these two methods were compared to determine the number of SLNs and the number of SLNs positive in 34 SLNs positive patients. <b>Results</b> This study included 163 patients with tumor (T)1-2 node (N)0-3 metastasis (M)0. The identification rate of SLNs was 100% for CEUS. We detected 376 SLNs using a combined CEUS and methylene blue method, with a median of 2 (1, 5). Furthermore, methylene blue identified 627 SLNs, with a median of 3 (1, 12). However, CEUS detected a significantly lower number of SLNs than those identified by methylene blue (<i>p</i> < 0.001). Additionally, metastasis frequency was substantially higher for the combined CEUS and methylene blue method (66.3%, 53/80) compared to methylene blue approach alone (39.5%, 58/147) (<i>p</i> < 0.001). <b>Conclusion</b> Combining CEUS with methylene blue is expected to improve the accuracy of axillary staging in breast cancer patients while reducing surgical trauma and postoperative complications.