Complementary Value of CEUS-Guided Hookwire Localization Combined with Methylene Blue Staining for Sentinel Lymph Node Detection, and the Predictive Role of Imaging Grade for Nodal Metastasis: A Single-Arm Clinical Study

Background Accurate identification of sentinel lymph nodes (SLNs) is essential for tumor staging and surgical decision-making. Although dye-guided SLN biopsy is widely used in clinical practice, relying on a single detection modality may lead to imprecise localization or missed detection of SLNs. Contrast-enhanced ultrasound (CEUS) has recently emerged as a promising imaging technique for visualizing lymphatic drainage and identifying sentinel lymph nodes. Objective This study aimed to evaluate the complementary detection performance of CEUS-guided hookwire localization combined with methylene blue staining for sentinel lymph node identification and to explore the potential predictive value of CEUS imaging grade for SLN metastasis. Methods A total of 76 patients who underwent sentinel lymph node biopsy were included in this single-arm clinical study. All patients underwent preoperative CEUS-guided hookwire localization followed by intraoperative methylene blue staining for SLN identification. The detection patterns of SLNs by CEUS and methylene blue were recorded and compared. In addition, CEUS imaging classified lymph nodes into three grades (I, II, and III), and the association between CEUS grade and pathological SLN metastasis was analyzed. Results Sentinel lymph nodes were successfully identified in 73 of 76 patients, yielding an overall detection rate of 96.05%. A total of 79 SLNs were excised, with a mean of 1.04 nodes per patient. CEUS-guided hookwire localization and methylene blue staining demonstrated partial overlap in SLN identification. On a patient basis, 71 patients (93.42%) were identified by CEUS-guided hookwire localization, whereas 69 patients (90.79%) were identified by methylene blue staining, indicating complementary detection performance between the two techniques. Pathological examination revealed SLN metastasis in 7 patients (9.21%). Among these metastatic cases, SLNs were identified by either CEUS-guided hookwire localization or methylene blue staining in 7 patients, including 2 patients detected by CEUS-guided hookwire localization alone, 1 patient detected by methylene blue staining alone, and 4 patients detected by both methods. Furthermore, CEUS imaging grade was associated with SLN positivity. The positivity rates were 1.82% in grade I lymph nodes, 15.00% in grade II lymph nodes, and 100.00% in grade III lymph nodes. Conclusion: CEUS-guided hookwire localization combined with methylene blue staining demonstrates potential complementary value in sentinel lymph node detection. In addition, CEUS imaging grade may provide useful information for predicting SLN metastasis, suggesting a potential role of CEUS in improving the precision of SLN identification and risk stratification.