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

Background: Sentinel lymph node (SLN) biopsy is the standard procedure for axillary staging in early breast cancer. Lymphatic imaging after intraparenchymal microbubble injection has been reported in animal models. The aim of this study was to identify and localize SLNs before surgery by contrast-enhanced ultrasonography after intradermal injection of microbubbles in patients with breast cancer. Methods: Fifty-four consecutive consenting patients with primary breast cancer were recruited. Patients received a periareolar intradermal injection of microbubble contrast agent. Breast lymphatics were visualized by ultrasonography and followed to identify putative axillary SLNs. A guidewire was deployed to localize the SLN. The next day, patients underwent standard tumour excision and SLN biopsy. Results: SLNs were identified and guidewires inserted in 48 patients. In these patients operative findings confirmed that the wired lymph nodes were SLNs. The sensitivity of SLN detection, compared with radioisotope and blue dye, was 89 per cent. Five patients were found to have metastases in SLNs. In these patients the SLNs were identified correctly and localized before surgery with guidewires. Conclusion: SLNs may be identified and localized before surgery using contrast-enhanced ultrasonography after injection of microbubbles.