89Zr-Nanocolloidal Albumin-Based PET/CT Lymphoscintigraphy for Sentinel Node Detection in Head and Neck Cancer: Preclinical Results

Identifying sentinel nodes near the primary tumor remains a problem in, for example, head and neck cancer because of the limited resolution of current lymphoscintigraphic imaging when using Tc-99m-nanocolloidal albumin. This study describes the development and evaluation of a nanocolloidal albumin-based tracer specifically dedicated for high-resolution PET detection. Methods: Zr-89 was coupled to nanocolloidal albumin via the bifunctional chelate p-isothiocyanatobenzyldesferrioxamine B. Quality control tests, including particle size measurements, and in vivo biodistribution and imaging experiments in a rabbit lymphogenic metastasis model were performed. Results: Coupling of Zr-89 to nanocolloidal albumin appeared to be efficient, resulting in a stable product with a radiochemical purity greater than 95%, without affecting the particle size. PET showed distinguished uptake of Zr-89-nanocolloidal albumin in the sentinel nodes, with visualization of lymphatic vessels, and with a biodistribution comparable to Tc-99m-nanocolloidal albumin. Conclusion: Zr-89-nanocolloidal albumin is a promising tracer for sentinel node detection by PET.