SENTINEL LYMPH-NODE UPTAKE OF 2 DIFFERENT TECHNETIUM-LABELED RADIOCOLLOIDS

Background: The study was designed to compare the uptake of technetium -(99m)-labeled human serum albumin ([Tc-99m]HSA) and (99m)technetium-l abeled sulfur colloid ([Tc-99m]SC) in the sentinel lymph nodes (SLNs). Methods: Radiocolloid levels in the SLN, femoral lymph node (FLN), is chial lymph node (ILN), spleen (SP), and right rear footpad (RRF) were quantitated over a period of 240 min after injection of [Tc-99m]SC or [Tc-99m]HSA into the rear footpad pf C57 BL/6 mice. Results: There wa s a significantly greater (p < 0.001) radioactive count in SLNs after [Tc-99m]SC (mean cpm 211,084.8) compared to [Tc-99m]HSA (mean cpm 115, 640.8), In contrast, the counts in the FLNs were higher after [Tc-99m] HSA (mean cpm 11,333.4) than after [Tc-99m]SC injection (mean cpm 5,06 5.5), The percent uptake in the SP was higher after [Tc-99m]HSA than a fter [Tc-99m]SC injection. Conclusions: [Tc-99m]SC is rapidly and effi ciently taken up by lymphatics at the primary injection site, is signi ficantly retained in the SLN, and flows slowly to the next echelon nod e (FLN or ILN) and to the systemic circulation (SP), [Tc-99m]HSA tends to accumulate less efficiently in the SLN and to disperse more rapidl y to the next echelon nodes and to the systemic circulation. By extrap olation, [Tc-99m]SC is likely to be a better radiocolloid for the intr aoperative detection of SLNs.