Technetium-99m calcium phytate--optimization of calcium content for liver and spleen scintigraphy: concise communication.

The addition of ionic calcium to technetium-99m stannous phytate produced an agent with improved splenic uptake. In a series of patients, it was found that molar ratios of 2:1 and 3:1 produced scans of optimal diagnostic quality. Studies in mice showed dose-related changes in the biodistribution. Electron microscopy demonstrated that the addition of calcium produced progressive aggregation of the colloid as the molar ratio was increased. Chemical analysis of sodium phytate was essential to obtain accurate ratios.