[Tracers used for the detection of sentinel lymph nodes]

The dye or isotope technique is generally used for sentinel lymph node mapping. There are many types of tracers available for the two techniques, and it is important to understand their characteristics such as particle size for appropriate use in specific diseases or conditions. There is an increasing tendency to use indocyanine green or indigo carmine dye instead of isosulfan or sulfan blue dye to avoid potentially life-threatening allergic reactions. Sentinel lymph nodes can easily be detected with the dye method 5-20 min after peritumoral tracer injection. When using dye mapping alone, sentinel lymph node detection should be achieved before the dye reaches nonsentinel nodes. Technetium-99m-labeled tin-colloid or phytate is frequently used in the isotope technique. Isotope injection the day before surgery can reduce the effects of the shine-through phenomenon. Lymphoscintigraphy often permits preoperative sentinel lymph node detection as a guide to intraoperative survey. In current practice, the combination of a radioisotope and blue dye for lymphatic mapping is thought to improve the sentinel lymph node identification rate. New techniques such as fluorescence imaging are being investigated.