In vivo evaluation of three different Tc-99m-labelled radiopharmaceuticalsfor sentinel lymph node identification

This work was designed to compare sentinel lymph node (SLN) uptake of Tc-99 m-labelled human serum albumin colloid (Tc-99m-HSAC), Tc-99m-labelled antim ony sulphur colloid (Tc-99m-SC) and a Tc-99m-labelled dextran 70 solution ( Tc-99m-Dx) and their selectivity in the identification of this node in the right rear footpad (RRF) of normal mice and tumour bearing mice. Radiopharm aceutical uptake in the SLN (popliteal lymph node) and the lumbar lymph nod e (LLN), the second lymphatic node station from RRF, were measured at diffe rent time points post-intradermal or intratumoural injection into the RRF o f NIH normal mice and of Balb/c mice harbouring the murine mammary tumour M 2. Tc-99m-HSAC uptake in the SLN was significantly higher than LLN uptake. The Tc-99m-SC demonstrated high uptake in SLN, but accumulation in LLN was also high. Tc-99m-Dx showed low uptakes in both SLN and LLN. The intraderma l injection resulted in a more effective radiopharmaceutical accumulation i n SLN than did the intratumoural inoculation. Data also show that increment s in tumour volume reduced radiopharmaceutical uptake in the SLN. Our resul ts show that Tc-99m-HSAC exhibits the highest uptake in the SLN combined wi th the smallest amounts of radiopharmaceutical passing through to the LLN. Therefore, Tc-99m-HSAC appears to be the best radiopharmaceutical for senti nel node detection. ((C) 2001 Lippincott Williams & Wilkins).