Paired-Agent Fluorescence Molecular Imaging of Sentinel Lymph Nodes Using Indocyanine Green as a Control Agent for Antibody-Based Targeted Agents

Figure 3

Kinetics of the antibody-based agent (IRDye-700DX-IgG) and ICG signal in a rat popliteal lymph node over time after intradermal footpad injection. Fluorescence images of ICG (green) and antibody-based agent (labeled IRDye-700CW-IgG; red) in the popliteal lymph node at 1 h after injection of the right rear footpad are presented in (a) and (b), respectively. The time course of fluorescence from both imaging agents failed to correlate with each other when all agents were mixed simultaneously just prior to injection as shown in (e). After the correction of mixing order and the preloading time, the potential ability for ICG to mimic the delivery and retention of an antibody-based imaging agent is presented in (c), depicting the mean fluorescence for both imaging agents in n = 5 rats in the lymph nodes as a function of time (error bars are SE). The binding potential for lymph nodes as a function of time after injection is presented in (d), with a maximum error of less than 0.05 in the absence of binding, further offering strong support that ICG is ideal for use as a control imaging agent in the PAISLY approach.

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