Indocyanine green-assisted sentinel lymph node biopsy in melanoma using the "FOVIS" system

Abstract

Background: Metastatic involvement of the sentinel lymph node (SLN) represents a key prognostic factor in melanoma. The combined use of a radiocolloid (technetium-99m) and blue dye is the gold standard in sentinel lymph node biopsy (SLNB). In this context, near-infrared (NIR) fluorescence imaging with indocyanine green (ICG) has been suggested as an alternative. The objective of the present study was to examine the potential advantages of fluorescence-guided SLNB - compared to the conventional method - with respect to the visualization of lymphatic drainage pathways and the SLN. Particular focus was on the impact of the ICG dose used and the body mass index (BMI).

Patients and methods: The study included ten patients who underwent the SLNB procedure using technetium-99m, blue dye, and ICG. Real-time fluorescence imaging of lymphatic drainage pathways and the SLN was done using the "FOVIS"-NIR system. Depending on the quality of the images achieved, ICG was intradermally administered at a dose ranging from 0.25 to 2.5 mg.

Results: Nine SLNs were identified by fluorescence (90 %); (100 %) ten, by gamma probe; eight (80 %), by ICG or blue dye. Transdermal SLN detection was possible in one case (10 %). In correlation to the BMI, higher intradermal ICG doses - up to 2.5 mg overall - proved to be advantageous in the visualization of lymphatic vessels.

Conclusions: Supplementing the technetium-99m method, fluorescence SLNB using ICG and the "FOVIS"-NIR system is a safe alternative to the blue-dye technique. Further studies on the optimal ICG dose and transdermal imaging in correlation to the BMI are required.