Definition of sentinel lymph node status using contrast-enhanced ultrasound with microbubble contrast agent in patients with primarily operable breast cancer

Currently, domestic literature lacks consolidated data on the feasibility of preserving the regional lymphatic basin, making the implementation of sentinel lymph node (SLN) mapping highly relevant in oncological practice as one of the most informative and least invasive surgical approaches. In this regard, the trend towards omitting SLN biopsy in selected patients seems timely, especially when contrast-enhanced ultrasound (CEUS) can identify SLNs and potentially assess tumor involvement based on enhancement patterns in early-stage breast cancer (BC).
Aim: To assess the diagnostic performance of CEUS using Sonovue (microbubble contrast agent) in detecting metastatic lymph nodes in early-stage breast cancer.
Materials and Methods: Between January and May 2025, 41 patients with histologically confirmed early breast cancer  (Tis–T2N0-1) were prospectively enrolled at the P.A. Herzen Moscow Research Oncology Institute. The median patient age was 58.3 years [48.5; 64.1]. Stage I disease was diagnosed in 33 patients (80.5%): stage IA in 21 (51.2%) and stage IB in 12 (29.3%). Invasive ductal carcinoma was confirmed in 31 patients (75.6%), and luminal A subtype in 15 patients (36.6%). Multicentric tumor growth was observed in 6 patients (14.6%). 
Conclusion: Advantages of CEUS with Sonovue include procedural simplicity and the ability to assess lymph node status preoperatively. However, limitations such as low sensitivity, high false-negative rate, and significant cost restrict its routine clinical application in patients with Tis–T2N0-1 breast cancer.