Ytterbium-169-phytate: a potential new radiopharmaceutical for functional scintigraphy of the liver

A new radiopharmaceutical for liver scintigraphy has been prepared by reacting 169YbOCl with Na phytate under conditions which yield a labelling efficiency of more than 99% over a wide pH range. In rabbits the resultant colloidal preparation shows a rapid elimination from the blood and high initial uptake in liver. Subsequently about 90% of the liver activity is lost within 3 days, the remainder being eliminated more slowly. The radiopharmaceutical is non-toxic and has a shelf-life of about 3 months. Scintigrams obtained in patients with hepatomegaly suggest that this new agent gives better visualization of space occupying lesions of the liver than 99mTc-Sn colloid. The radiation dose to the patient from this agent is low and comparable with that from other radiopharmaceuticals used for liver scintigraphy.