Tracers and corresponding detection devices: technetium colloids, blue dyes & NIR fluorescence

Tracers and corresponding detection devices for the mapping of sentinel lymph nodes have been evolving since the first use of lymphangiogram methods in 1977 in penile carcinoma. Nowadays a variety of dyes and radiotracers have been validated for use in breast, vulvar and cervical cancer as well as melanoma. Each tumor site with its anatomical conditions requires different mapping protocol. While the combination of radiotracer and blue dye or radiotracer alone is an established method for breast surgery, vulvar cancer and melanoma, in pelvic sentinel lymph node mapping indocyanine green is currently gaining popularity. Near infrared fluorescence imaging is an emerging technique that enables a real-time image-guided procedure and is currently approved by the Food and Drug Administration as a sentinel lymph node mapping substance with standard of care. New tracers and devices are constantly under investigation to better understand the pathway of lymphatic drainage and increase the sensibility and sensitivity of the method. In the present review the evolution of available tracers and detection devices is discussed. An exhaustive review of current clinical indications of each method, its particularities and adverse effects is made. Finally, an update on ongoing clinical studies in sentinel lymph node mapping methods is presented.