Preoperative localization of sentinel lymph nodes using percutaneous contrast-enhanced ultrasonography in patients with breast cancer

This study aimed to investigate the feasibility of preoperative identification of sentinel lymph nodes (SLNs) by contrast-enhanced ultrasound (CEUS) for patients with breast cancer. The patients with T1-T2N0M0 breast cancer who were scheduled for primary surgical treatment were recruited. All the patients had received a periareolar intradermal injection of an ultrasonic contrast agent (SonoVue, Bracco, Milan, Italy) followed by an ultrasound to identify contrast-enhanced SLNs. A guidewire was deployed to localize the SLN. Methylene blue stain was used to help trace SLNs during the operation. The identification rate and accuracy rate were recorded. The number of SLNs labeled by two methods was counted and compared using Wilcoxon testing. A total of 366 SLNs were detected in 72 patients by methylene blue intraoperatively, with a median of 5 lymph nodes [interquartile range (IQR), 4-6] per patient. A total of 95 SLNs were detected in 63 patients (87.5%) by CEUS, with a median of 1 lymph node (IQR, 1-2) per patient. The number of SLNs detected by CEUS was significantly less than that labeled by the methylene blue staining method (Z=-7.362, P=0000). Pathology confirmed 12 single metastases in all the lymph nodes examined, 10 of which were the only lymph node identified by CEUS. Periareolar intradermal injection of an ultrasonic contrast agent was an effective and convenient supplementary to localize SLNs. The technique was expected to improve the accuracy of axillary staging with minor surgical trauma and postoperative complications.