Lymphatic Contrast-enhanced Ultrasound as a Noninvasive Predictor of Sentinel Lymph Node Metastasis in Breast Cancer: A Prospective Diagnostic Study

Sentinel lymph node biopsy (SLNB) using radioisotopes/blue dye remains limited by radiation exposure and logistical constraints. This study prospectively evaluates lymphatic contrast-enhanced ultrasound (L-CEUS) for SLN mapping and metastasis detection in early-stage breast cancer. A total of 251 consecutive patients underwent L-CEUS-guided SLN biopsy. Enhancement patterns (Types I-V) and filling defects were correlated with histopathology. Diagnostic performance was compared to conventional ultrasound parameters and surgical SLNB (n = 102). L-CEUS successfully localized SLNs in 98.4% (247/251) of cases. Using Types III-V enhancement as metastatic criteria, L-CEUS demonstrated 99.0% sensitivity and 88.1% specificity (AUC 0.935). Incorporating filling defects improved specificity to 95.4% (AUC 0.967). Cortical thickness (>3.0 mm) outperformed nodal short-axis in metastasis prediction (AUC 0.874 vs. 0.702, p < 0.001). Compared with blue dye, L-CEUS identified fewer SLNs/patient (3.11 ± 0.81 vs. 3.59 ± 1.2, p = 0.001) with shorter procedural time (4.09 ± 0.25 vs. 12.12 ± 2.75 min, p < 0.001). Eight false-negatives involved micro-metastases (n = 3) and skip lesions (n = 5). L-CEUS provides high diagnostic accuracy for SLN evaluation while eliminating radiation exposure. Its real-time imaging capability and rapid procedural time support integration into standard axillary staging protocols, particularly where radioisotopes are unavailable. Prospective validation of long-term outcomes is warranted.