Comparison of Liposomal and Aqueous Blue Dye in Visualization of Lymph Nodes Prior to Lymphadenectomy

Abstract

AbstractIntraoperative identification of regional lymph nodes is massively improved by their effective preoperative staining, which is necessary for the selectivity of sentinel node lymphadenectomy. Currently used aqueous dye solutions, such as Patent Blue V (PBV), do not reliably provide the necessary properties regarding intensity and duration of contrast.To find a better substance for preoperative staining, a study was designed, in which conventional PBV in aqueous solution and PBV encapsulated in liposomes were compared in terms of their staining properties.An extrusion technique using membranes with a thickness of 0.2, 0.4, and 5 µm supplied lecithin–cholesterol liposomes in a molar ratio of 3:1. For the experiment, eight female pigs with an average weight of 40 kg were used. Each pig was administered a 0.5-ml depot containing 12.5 ± 0.2 mg of aqueous PBV into each of the four upper and lower mammary glands on the left side. On the right side, the same dosage of PBV encapsulated in liposomes was injected.After 3, 6, 12, and 24 hours stained lymph nodes of the neck, pelvis, and groin were excised and photographically documented. Their respective PBV concentrations were additionally analyzed by spectrophotometry. It was found that in each case the intensity and duration of staining were better in case of liposomal dye. It is, therefore, recommended to prefer PBV encapsulated in liposomes for preoperative staining and the identification of sentinel lymph nodes.Key Wordslymph node stainingsentinel nodeliposomes