Potential radiopharmaceuticals labeled with titanium-45.

The potential of some compounds labeled with cyclotron-produced titanium-45 (45Ti) as radiopharmaceuticals was studied. Properties of colloid formation of 45TiOCl2 or 45TiO-phytate in vivo resulted in the highest radioactivity uptake in the rat liver, followed by the spleen, suggesting potential for imaging the reticuloendothelial system. Three 45TiO-complexes with diethylenetriaminepentaacetic acid, citric acid and human serum albumin showed the highest radioactivity levels in the blood over 6 h. The binding of the 45Ti with plasma transferrin in vitro and in vivo suggested that these compounds can be used for estimating the blood volume. Also, potential as an indicator representing the breakdown of the blood-brain barrier in the rat was demonstrated by autoradiography.