At which site does Tc tilmanocept deliver the highest dose?

• A. Liver
• B. Injection site
• C. Spleen
• D. Bone marrow

Answer: (B)

Tc tilmanocept is a radiopharmaceutical that is designed for use in lymphatic mapping, particularly in procedures such as sentinel lymph node biopsy. When injected, it is specifically formulated to target the lymphatic system, and its distribution is influenced by the anatomical and physiological characteristics of the individual.

The highest dose delivered by Tc tilmanocept occurs at the injection site due to the concentrated nature of the radiopharmaceutical immediately where it is administered. This localized accumulation is because the radioactivity is highest at the point of injection before it begins to disperse through the lymphatic system. The characteristics of tilmanocept, which helps in effectively tracing the lymphatic pathways, add to its localization at the injection site.

In contrast, other sites like the liver, spleen, or bone marrow do not receive the same concentration of the radiopharmaceutical upon administration. This is because the hepatic and splenic uptake involves systemic circulation and distribution, where the radiopharmaceutical is diluted and does not accumulate as intensely as at the injection site. Therefore, the understanding of the pharmacokinetics of Tc tilmanocept highlights that the injection site is indeed where the highest dose is delivered initially.