Human albumin colloid

An ICG stock solution was prepared by adding 5 ml of sterile water to a vial of 25 mg of dry compound ICG (Pulsion Medical, Germany). Nanocoll (GE Healthcare, UK) was prepared by adding 2 ml of isotone saline water to a vial containing 0.5 mg of human albumin colloid (GE Healthcare, UK). Then 0.2 ml of the ICG solution and 0.2 ml of the Nanocoll was carefully mixed in a syringe and left for 5 min of incubation. The final mixture with a volume of 0.4 ml, containing 1 mg of ICG (3.2 mM) was prepared in a 1 ml syringe with a 25G needle for injection. Based on electron microscopy imaging it has been estimated, that the molar ICG/Nanocoll ratio in the unconjuncgated ICG-Nanocoll tracer complex, where Nanocoll is saturated with ICG, is 61:1 [24] . The molar ICG/Nanocoll ratio of the ICG-Nanocoll tracer complex used in this study was 1.800:1. Therefore, in the injected tracer preparation, a substantial part of ICG was unbound ICG, to allow rapid drainage to the entire tumorrelated neck lymphatics. Patients were injected the day before or the day of surgery after application of local spray anesthesia in four submucosal peritumoral deposits.