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

Abstract

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.

Challenges in Preparation of Albumin Nanoparticle-Based Radiopharmaceuticals

“…The fate of subcutaneously/interstitially administered radiocolloids has been outlined as the following sequence: phagocytosis by histocytes at the injection site; transport via lymph vessels to the regional lymph nodes; phagocytosis by macrophages in the lymph nodes; transport via blood vessels to the liver, spleen, and bone marrow; and elimination within the reticuloendothelial system [ 25 ].…”

“…A new agent is commonly compared to a gold standard; however, for sentinel node imaging, the gold standard varies around the world, as has been summarised [ 19 , 25 ]. Despite the variety of agents with different properties used in different jurisdictions, there is no indication that there are geographical differences in the sensitivity of the sentinel node procedure [ 19 ].…”

Predictors of Bilateral SLN Radiocolloid Detection in Endometrial Carcinoma

“…3 Colorimetric, radionuclide, and fluorescent methods are currently the most commonly used techniques for SLN detection. 4 After interstitial application, the radiocolloid enters the lymphatic capillaries and through the lymph vessels reaches the first drainage lymph node, where it remains trapped by the macrophages, unlike other tracers that are characterized by rapid lymphatic clearance. This provides a unique opportunity for preoperative localization of the SLN on a planar lymphoscintigraphy and single photon emission computed tomography/computed tomography (SPECT/CT), by which significantly eases the SLN detection, thus reducing the time duration of the surgical intervention.…”

“…3 Colorimetric, radionuclide, and fluorescent methods are currently the most commonly used techniques for SLN detection. 4…”