Size and specificity of radiopharmaceuticals for sentinel lymph node detection.

BackgroundBiological performance of radiotracers for sentinel node detection analyzed in the light of molecular design and dimension is not widely available.PurposeTo evaluate the effect of dextran molecular size and the presence of tissue-binding units (mannose) within the model of 99mTc-carbonyl conjugate for sentinel lymph node detection.Material and MethodsFour dextran conjugates with and without mannose in the chemical backbone were included. All polymers were radiolabeled using the precursor [99mTc(OH2)3(CO)3]+. Radiolabeling conditions targeted the best radiochemical purity and specific activity for each radiopharmaceutical, and partition coefficients were also defined. Lymphoscintigraphy and ex-vivo biodistribution in popliteal lymph node, liver and kidneys were performed in Wistar rats. The effects of molecular weight and mannose presence were assessed by a two-level factorial design.ResultsRadiochemical purity was indirectly related to molecular weight and presence of mannose in the polymer stru...