Percutaneous removal of sentinel lymph nodes in a swine model using a breast lesion excision system and contrast-enhanced ultrasound.

Objectives: To investigate the feasibility of percutaneous removal of the entire sentinel lymph node (SLN) in an animal model using a breast lesion excision system after identifying these nodes using contrast-enhanced ultrasound (CEUS) and intradermal microbubbles.

Methods: Animal studies approval was obtained. SLNs were identified using CEUS and intradermal injection of microbubbles in two young pigs. Microbubbles were mixed with blue dye and injected around the mammary papillae to access lymphatic drainage to the superficial inguinal lymph nodes. When enhancing nodes were identified, the breast lesion excision system (BLES) was used to remove these nodes percutaneously. Both animals then underwent surgical lymph node dissection. Histopathological examination of all the samples was performed.

Results: Removal of the entire SLN was successful in three groins in the pigs. All three nodes were stained with blue dye. No other stained nodes were observed in the node dissection specimens. The nodal architecture of removed lymph nodes was well preserved on microscopy. There were no signs of excess trauma within the biopsy bed.

Conclusion: The results obtained from the swine model demonstrated that it is feasible to remove the entire SLN percutaneously under the guidance of CEUS and microbubbles.

Key Points: Intradermal injection of microbubbles and CEUS can identify sentinel lymph nodes • Ultrasound could then guide percutaneous removal of intact and complete SLNs • We have shown this was feasible in pigs but not yet in humans • This technique may eventually have the potential to reduce futile SLN biopsies.