Which radiopharmaceutical is not prepared with reduced Tc-99?

Sulfur colloid is not prepared with reduced technetium-99m (Tc-99m) because it is a colloidal suspension of particles composed of sulfur, which does not require the reduction process that is necessary for the formation of radiopharmaceuticals like Tc-99m-pertechnetate, Tc-99m-DTPA, and Tc-99m-MAG3.

In contrast, the other compounds listed, such as Tc-99m-pertechnetate, rely on Tc-99m being in a reduced form to facilitate their specific chemical properties and imaging capabilities. Tc-99m is generally reduced in a controlled environment to combine with other compounds effectively, ensuring proper binding and functionality required for diagnostic imaging procedures. Thus, sulfur colloid stands out as it operates differently and does not rely on reduced forms of Tc-99.