In-111 Zevalin is performed to confirm that the biodistribution of the radiopharmaceutical is normal prior to treatment of the patient with Yttrium-90 Zevalin. Zevalin is an immunoconjugate consisting of the monoclonal antibody Ibritumomab and the linker-chelator tiuxetan. Ibritumomab is a murine IgG1monoclonal antibody that targets the CD20 antigen found on the surface of normal and malignant B lymphocytes.
Initially, Indium-111 Zevalin is expected to be seen in the blood pool with progressively less blood pool activity over time. There is moderate to high uptake seen in the normal liver and spleen, with low uptake in the lungs, kidneys, and urinary bladder.
Tumor uptake may be visualized in soft tissue as areas of increased intensity, and tumor-bearing areas in normal organs may be seen as areas of increased or decreased intensity.
In this case, there is expected whole-body biodistribution of the Indium-111 Zevalin radiotracer as well as focal increased radiotracer activity in regions of known hypermetabolic lymphadenopathy corresponding to the recurrent follicular lymphoma. The patient subsequently received 30 mCi of Yttrium-90 Zevalin therapy.
