On-site preparation of technetium-99m labeled human serum albumin for clinical application.

Technetium-99m labeled human serum albumin (Tc-99m HSA) is an important radiopharmaceutical for clinical applications, such as cardiac function tests or protein-losing gastroenteropathy assessment. However, because of transfusion-induced infectious diseases, the safety of serum products is a serious concern. In this context, serum products acquired from patients themselves are the most ideal tracer. However, the development of rapid separation and easy clinical labeling methods is not yet well established. Under such situation, products from the same ethnic group or country are now recommended by the World Health Organization as an alternative preparation. This article describes the on-site preparation of Tc-99m HSA from locally supplied serum products. Different formulations were prepared and the labeling efficiency and stability were examined. Radio-labeling efficiencies were more than 90% in all preparation protocols, except for one that omitted the stannous solution. The most cost-effective protocol contained HSA 0.1 mg, treated with stannous fluoride 0.2 mg, and mixed with Tc-99m pertechnetate 30 mCi. A biodistribution study was performed in rats using a gamma camera immediately after intravenous administration of radiolabeled HSA. Tissue/organ uptake was obtained by measuring the radioactivity in organs after sacrificing the rats at timed intervals. The biologic half-life was about 32 min, determined from sequential venous blood collections. These data indicate that our preparation of Tc-99m HSA is useful and potentially applicable clinically. In addition, this on-site preparation provides the possibility of labeling a patient's own serum for subsequent clinical application.