New Technologies for Sentinel Lymph Node Detection

The 'standard of care' method for sentinel node mapping is the combination technique using radioisotope and blue dye although some centres use radioisotope or blue dye alone. Radioisotope usage requires licensing, has regulatory issues around handling and disposal of waste, and logistically may be unavailable or difficult to implement in some centres or less developed country. This has led to the development of alternative methods such as superparamagnetic iron oxide (SPIO), fluorescence techniques using indocyanine green (ICG) or fluorescein, computed tomography lymphography, and contrast-enhanced ultrasound scan (CEUS) using microbubbles. The newer techniques will potentially enable a more widespread adoption of this procedure; however, a common barrier for these techniques is the lack of standardisation and no randomised trials to evaluate their effectiveness against the current standard of care. Furthermore, many of these techniques are more costly and may become redundant in node-negative patients with small tumours if ongoing trials show that sentinel node biopsy offers no additional benefit to grey-scale axillary ultrasound. This review discusses the new techniques for sentinel node mapping that have emerged including their pros and cons.