Which radiopharmaceutical is used as a marker of cellular proliferation?

18F-Fluorothymidine (FLT) is widely recognized as a radiopharmaceutical used to assess cellular proliferation. The mechanism behind FLT's function lies in its similarity to thymidine, a nucleoside critical for DNA synthesis. During cellular division, proliferating cells incorporate FLT into their newly synthesized DNA in a manner analogous to how they would incorporate thymidine. This incorporation can be measured using PET imaging, providing an effective means of evaluating the growth rates of tumors or other proliferating tissues. FLT's use in clinical settings has demonstrated its ability to reflect the biological activity of tumors, making it a valuable tool in oncology for monitoring treatment response and assessing tumor aggressiveness.

The other radiopharmaceuticals listed are used for different purposes, such as evaluating bone metabolism and assessing the function of certain organs, but they do not serve as specific markers for cellular proliferation.